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Plant Bio Bundle Notes

by: Sarah Bawany

Plant Bio Bundle Notes BIO 322

Marketplace > University of Texas at Austin > Biology > BIO 322 > Plant Bio Bundle Notes
Sarah Bawany
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Robert Fulginiti

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Robert Fulginiti
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This 24 page Bundle was uploaded by Sarah Bawany on Tuesday September 22, 2015. The Bundle belongs to BIO 322 at University of Texas at Austin taught by Robert Fulginiti in Summer 2015. Since its upload, it has received 11 views. For similar materials see STRUC/PHYS/REPRO OF SEED PLANT in Biology at University of Texas at Austin.


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Date Created: 09/22/15
Plant Biology Summer Session 2 EXAM 1 MATERIAL 071315 Structure vs Physiology Checklist of plants leaves stems roots structures can be very modi ed in shape or size so that they appear absent obvious exception cacti but looking at where spines come out you can see millimeter long leaf structures so every plant has those Photosynthesis occurs organism does what it does because evolutionarily it was trained to theres a type of plant very small described as being white lacks chlorophyll so is this plant photosynthetic no it is not so why is it still a plant and if it can t photosynthesize what is its source of energy they are parasitic plants parasitic on roots of nearby plants Physiology photosynthesis is most obvious process radiant energy converted to chemical bond energy in form of sugar 07141 5 Prokaryotes table 01 Domain Archaea more closely related to original forms of life on planet due to temperature etc Domain EuBacteria some are photosynthetic known as cyanobacteria e g bluegreen algae Eukaryotes Domain Eukarya Kingdom Protista unicellular include regular algae if multicellular then simple historically dumping ground if didn t t everywhere else went there Algae singlecelled colonial or very simple multicellular organisms problematic group because of metabolism photoS nearly identical to true plants below biochemically very similar to true plants same kind of cellulose gave rise to kingdom plantae most likely Kingdom Mycetaee fungi non photosynthetic weird reproductive cycles not considered plants not green and don t get energy from sunlight Kingdom Animalia animals Kingdom Plantae contains 17 divisions PhylumDivision Bryophyta mosses liverworts of all terrestrial plants mosses have the least in common w owering plants don t have true stemsleavesroots Division Pterodophyta ferns have several features in common with owering plants have leaves stems roots Division Coniferophyta gymnosperms conifers like pine produce seeds in cones like owering plants are seed plants Division Magnoliophyta owering plants going to start and finish Chapter 1 today Greenness of plant is hint not of structure but of metabolism photosynthesis Leaves lacking in bryophyta leaflike structures Stems lacking in bryophyta Flowers lacking in bryophyta Roots lacking in bryophyta rootlike structures exclusion of certain groups inclusion of some groups strong selection pressures in plants because they are stationary so they have to be more sensitive and responsive to environment e g when we talk about a sun ower we talk about both the individual plant as well as all the members of its species what you see in group tells you about genetic potential at particular time of the species Anthropomorphismic human qualities to nonhuman things teleological problematic thought implies that something has a purpose plants produce roots in order to absorb water vs plant roots absorb water 2nd way is proper scientific way to say it function does NOT imply purpose Function is what its doing how it got there is evolution via natural selection evolution change in gene composition through multiple generationslong periods of time gradual change in population over time by natural selection variation in a pop through genetic level some genes allow organism to be better adapted to reproduce because environment is changing there is no perfect adaptive form for anything if organisms evolve they should be able to adapt to new environmentclimate but problem is time that its happening too rapidly that change will select for organisms with short generation time so bacteria will inherit Earth 071515 See Figure 113 Earth 4245 billion years old Universe about 14 billion years old First type of living system about 3738 bya gt earliest prokaryote People don t look for presence of cells but something chemical to conclude that cells were once present From early prokaryotes diversity of later prokaryotes evolved At some point we see cellular respiration not aerobic but anaerobic because early atmosphere had no 02 gt doesn t appear until photosynthesis begins about 28 bya as a metabolic process probably not present in all prokaryotes but in some Profound event genetic material became enclosed in double membrane nucleus once that happened you find eukaryotic cells in addition to prokaryotic cells Selective advantage is strong allows cell more control over process ability to control material transport concentrating certain materials in one area enables higher reaction rates Eukaryotic cell 2 bya at about same time we see Eukaryote cells containing 2 organelles nucleus Photosynthesis associated wmembranes believed that early eukaryotic cells engulfed photosynthetic prokaryotes and produced chloroplasts and mitochondria Endosymbiotic theory is above theory looking at mitochondria genome and its RNA it is similar to prokaryotic bacteria Prokaryotes have circular DNA strands genetic material in chromosomes is linear DNA in mitochondria and chloroplasts are circular RNA of prokaryotes and eukaryotes are different but RNA of chloromito are almost indistinguishable from prokaryotic RNA gt about 1 billion year ago first photosynthetic eukaryote The chloroplast cell gave rise to protista algae and plants The one without chloroplast and just mitochondria gave rise to everything else fungi animals Rate of evolution not uniform for different organisms Can generate mutations at diff rates organisms exist in different environments with different environmental pressures same for evolution of structures Driving force is natural selection Mosses today vs Mosses 5 million years ago none of these things have evolved that much if you look at fossilized mosses you can identify them by species when you see certain similar features between present and ancestor Relictual features not changed much throughout evolution similar to those in ancestor Also known as plesiomorphic features When looking at owing plants you see mix of plesiomorphic features and features that appeared recenty aka derived new features Aka apomorphic features Asters owers that are apomorphic leaves by chemical composition contain bitter substances which was also present in ancestors plesiomorphic but if you look at shape very new innovation broad and at increases photosynthetic proficiency apomorphic so in same organ you can find many features that are derived or old true for all organisms Woodpresent day aster wood is more efficient in conducting water with lot less friction so more efficient in water conduction compared to ancestor s e g plesiomorphic Starting Chapter 3 today Chapter 2 is basic review of chemistry read if you don t remember lipids carbs etc Benefits and disadvantages of being multicellular Good allows for specialization and division of labor Bad requires more energy dependency on other cells e g root cells depend on cells that can photosynthesize for energy If photosynthetic cells that die can affect cells that didn t receive that damage because they were dependent on first cells Redundancy built into plants which lessen negative consequences Think about 1st 2 pages of Ch4 most algae are aquatic transformation of aquatic plants to being true bloom land plants gt 420 mya gt created enormous selective pressures e g competition for sunlight e g transport system to transport water where its located soil to plant itself this event explains many plant adaptations what happens when inside environment is equal to outside environment Death We see lots of energy dedicated to exception of 2nd law of thermodynamics 071715 missed class read book look over review questions in the back They are good to look over Membranes Phospholipids and Membrane Fluidity the overall structure of membrane is due to chemical nature of phospholipids Membrane uidity we mean how liquid the phospholipid bilayer is Its basically and oil At room temperature is has the consistency of vegetable oil Cool it down less liquidity More heat more liquidity How uid the membrane is affects its permeability The uidity has a direct effect on membrane phospholipid bilayer permeability Membrane uidity is under the control of the cell the cell can alter based on cell needs membrane uidity is how liquid the membrane is Individual phospholipids and whats embedded certain types of movement of phospholipids are more probable than others Can one phospholipid head switch to the other side Its highly unlikely because the polar had has to cross the hydrophobic tails The lateral movement within a given layer is common and happens quickly 1 The least important way to do It is to alter the lengths of the fatty acids Alter the shape of phospholipids fatty tails 2 change the degree of satu and unsat No double bond hydrocarbon chain is saturated Double bond has kinks is unsaturated Kinks push each other apart unsaturated would be more uid due to less interaction of fatty acid tails So if cell needs to regulate permeability of membrane you may see phospholipids with unsaturated tails be presently synthesized Unsaturated tails less interactions between fatty acid tails of adjacent phospholipid cells Saturated lying side by side so greater interactions between tails 3 Cholesterol used to regulate membrane uidity If cholesterol were inserted between phospholipids it would weakly interact with it The membrane would be less uid since you re linking adjacent tails but depends on temp by adding cholesterol you decrease uidity because its another action between phospholipids Cell membrane uidity is related to the strength of the membrane Extremely uid membrane may not be strong enough to hold cytoplasm Its ok for plants because they are surrounded by cellulose and is more important in animal cells rotational movement The movements that don t cross polar and nonpolar to move around is more probable theres interactions between phospholipids tails and collectively largely affect uidity The right one has less interactions so look over osmosis and diffusion Proteins critically important in membrane function Phospholipid bilayer in membrane will not allow any ions to pass It s a completely barrier to ions Only nonpolar can get pass the membrane With proteins all kinds of things can be transported through the cell Mainly transported via proteins Two types of proteins in membrane Relative to where you find them Integral Proteins usually amphipathic But not as strongly amphipathic as peripheral Interact more strongly with the membrane They have amino acids extensions that are nonpolarhydrophobic Regions can be continuous or discontinuous They will be interaction with the hydrophobic core Inserted within the depths of the membrane All transmembrane proteins are integral proteins Have numerous functions of these proteins one of them being transport They can form channels They can form pores The form ion pumps molecular pumps Form receptors Some are enzymes Example of pores are aquaporins All of this implies specialization for whats being transported Aqua porins gets across membranes faster than usual Not just because its small since its polar In the 80s it was discovered that small proteins would allow for the transport of water across the membrane These things formed pores and allow water to pass Peripheral Proteins located with both sides of the phospholipid bilayer Interact with heads on both sides of the membrane These interact with phospholipid heads tend to be lipid soluble Tend to interact with the faces of the membrane in a temporary fashion Not directly as involved in transport Can function as cell communication receptors and enzymes Diffusion high concentration to low concentration Osmosis diffusion of water across a membrane Facilitated diffusion high to low diffusion with the use of proteins Doesn t cost cell energy to do the transport Could be channels and pores Active Transport involved membrane protein from low to high and requires energy Such as molecular pumps Sugars Figure lA there are by weight 60 proteins 40 phospholipids But phospholipids still the most important Functionality with respect to transport thanks to proteins Figure lb integral proteins that form pores Sometime integral proteins to multipasses oligosaccharides or sugars are associated with the membrane 415 sugar residues Short chain Sugar molecules attached to proteins or phospholipid head Attached to protein glycoprotein Attached to phoshead call glycolipid Sugars are more important in plant that in animal cells Especially in the immune systems Through these sugars cells recognize other cells Plant cells are stuck in place they done move around Sugars not involved in the inside of the cell meaning no sugars inside attached to the membrane Can function as hormones Protoplasm plant cells or all for the material of the cell or cell with cell wall excluding the cell wall Protoplasts are plant cells without the cell wall Plant cells Cytoplasm protoplasm minus central vacuole and the nucleus Hyaloplasm equivalent to the animal term cytosol Everything in the cell that is not an organelle Just the uid in the cell Figure 7 saturated vs unsaturated tails via transport and membrane uidity Permeability on the arrow Cholesterol fatty acid tails of adjacent phospholipids links the adjacent phospholipids Less independent of each other Plant differ from animals 1 chloroplast 2 Central Vacuoles strange organelle Its structure is exceedingly simple Really simple Its essentially a uid filled space surrounded by a single membrane Appears to be uid lled Lipid bilayer but only one Membrane called the tonoplast Can be a huge organelle can take 90 of cell volume Many times you dont see vacuole is because its clear Vaculose have a siginificant role in the placement in the organelles Functions include involved in cell growth Think about osmosis Cell wall relatively rigid Inside cell we have a vacuole evolution states a simple way to grow plant cells Water enters the central vacuole Semirigid cell wall surround the plant cell Blow up balloon more and more exerting cell wall pressure via osmosis Water enters central vacuole cell wall is loosened Cell wall lossened cell gets bigger It reaches a programmed size Now you tighten us the wall make it more rigid Loosened accompanied by acidi ying the cell wall The wall is then neutralized so cellulose molecules can now rebind Initially you don t have to expand the cytoplasm Can produce cytoplasm at its own leisure Quiz on Wednesday 072015 Central Vacuole looking at plant cells can be dif cult to determine presence of central vacuole usually in center pushes cytoplasm so its just beneath cell wall when you first look at cellstained cell you will mostly see material in cytoplasm which is just beneath the cell walls what is being stained is the cytoplasm if cutting through cross section of plant cell you would have cytoplasm on edge and CV in middle with out of focus green smudges chloroplast people initially thought CV was empty most unstained things in cells have same refractive index as water in a prep objects bend light differently if they don t they appear homogenous all staining does is gives diff components of cell different refractive indices so we can discern it with our eyes functions are varied cell growth compare to animal cells when animal cell divides the progeny increase in size and there is an increase in amount of protoplasm for plant cell to grow all it needs is water in central vacuole and loosen cell wall to increase volume of cell don t need increase in protoplasm cell growth can mean 2 things increase in size or increase in cell number happens just due to water content of central vacuole cells will have to make more protocytoplasm delay protoplasm making until structure has more mature form because it expends lots of energy to make as cell increases in size increase in protoplasm as well central vacuole has critical involvement in cell growth and cell storage for short or long periods of time e g sometimes pigments for long term also calcium ions role of calcium ions serve as regulating biochemical reactions and secondary messengers activatedeactivate enzymatic reactions cell regulates calcium ion concentration in cytoplasm to regulate metabolism in cell by storing in CVnot really long term in CV potassium is critical nutrient lots of flow between CV to CP more short term than Ca some plants have biochemical advantage to store C02 as acid in CV plants don t have excretory systems generate toxic materials which are stored in CV Positive consequence storing toxic material in a cell makes cell less attractive to herbivores and insects tonoplast is outer part of CV active storage for short periods of time inactive storage for long periods of time Ca conc needs to be low in CF so movement is more from CP gt CV than vv in animal cells there are organelles in digestive enzymes plants don t have lysosomes but CV functions as lysosomes digestive function recycling of material pump precursors into CF to reuse materials Overall CV is dynamic organelle although it looks like empty space in micrograph Mitochondria aerobic cellular respiration cells need to store energy in highly energetic compoundsmolecules but molecules that are not super reactive sugars starches Aerobic cellular respiration takes sugarsstarches and converts them into high energy compounds that are highly reactive human at rest needs 50 kg a day in one second you have about 03 g of ATP ADP Pi lt gt ATP given any time you have little ATP present but you use an enormous amount in one day can t store it because highly reactive plant usually lump can be gt 5 pm more animallike compartmentalization in mitochondria so more highly reactive compounds in there prokyarotes don t have mitochondria so how do they deal with this 2 membranes inner membrane and outer membrane IM is folds called cristae function is to increase surface area having enzymes on membrane lets you precisely regulate outer membrane is almost freely permeable inner membrane is selectively permeable mitochondria has their own DNAcircular and ribosomes which differ very much from other ribosomes in cell lot smaller and similar to prokaryotic ribosomes DNA of mitochondria lack histone proteins just like prokaryote DNA Cells don t make mitochondria the mitochondria themselves make more mitochondria their division is superficially similar to binary fission MC smaller in plant cells than in animal around 1 pm can be spherical shaped difficult to see them in plant preps per cell can vary 10010000 Total volume of MC in cell gtgtgtgtgt of MC in cell general for volume of MC per plant cell is 125 depending on cell common feature among land plants especially is central vacuole not very prevalent in animal cells gt important for stem structuresupport photosynthesis capacity 99 organisms on planet dependent on photosynthesis gt or chloroplasts Chloroplasts belong to larger group of organelles known as plastids Plastids do more than just photosynthesize some also involve in AA synthesis lipid synthesis iron storage as ferophyte in animal cells stored in cytoplasm each plastid has specific metabolism each specifies in different things specialization is not static types of plastids present change with metabolic needs of cell 072115 formation of central vacuole as these cells grow they fuse together don t see central vacuoles in young cells verify beginning of this functions of vacuoles storage of materials called Rio in some seeds vacuole is where carbs are stored amp can be long term 530 years used as energy source for germinating seeds remain viable despite little rain e g wild owers Plastids can be involved in lipidAA synthesis store iron photosynthesis different specific plastids for each one Internal membranes that are derived from inner membrane of chloroplast thylakoid 2 types of organization attened sacs hollow interior phospholipid bilayer lumenspace inside stack of thylakoids known as granum grana singular handle radiant energy turning into electrical energy reduction of CO2 occurs in stoma but light reactions wphotosynthesis associated with thylakoid everything else mostly occurs in stroma actions associated with thylakoids create very reactive intermediates plastids known as proplastids have very little thylakoids if any at all can develop into any other kind of plastid globs inside chloroplast are temporary accumulation of sugars they are being produced faster than they can be exported out of the chloroplast e g reserve starch dark splotches are crystal stuff amyloplasts plastids that never photosynthesize but they specialize for storage of starch difficult to section starch rough material because can tear when you section it chromoplasts plastids that have pigments other than chlorophyll similar to pro plastids in general way eg you don t see discrete thylakoid membranes just grana can see some membranes but somewhat wavydisorganized conversion of chloroplast to chloroplast losing structure of thylakoid also deposits of pigments called plastoglobuilin us M all interconvertible with chloroplasts pigments in chromoplasts are called carotenoid 2 are lipid soluble in photosynthetic plant cells there are some carotenoids present so not limited to chromoplasts Carotenoids present are masked by presence of chlorophyll Fall coloration leaves change color you would think they are producing lots of carotenoids but thats not the case because chlorophyll is expensive to synthesize it simply stops being produced in the leaves so pigments that were already present are exposed these carotenoids are less attractive to herbivores 072215 Cell Wall all land plants except algae and sperm cells have a cell wall cell walls very persistent preserve well during specimen prep most of what you see in a stain is cell wall was thought to be inactive structure wstructural being main function involved in cell growth loosen cell wall resistant to bacterial and fungal decay mostly because of cellulose Fiber being huge polymer and bf lack resources to break it down betal4 glycosidic bond is the bond between glucose residues that prevent bf from decaying it eg termites have bacteria in stomach that breaks these bonds but bf don t have them residue called such because some parts are removed to bond with others e g chain of glucose diff macromolecules in cell wall along with cellulose cellulose synthesized in such a way that they are side by side close to other cellulose molecules and they interact through hydrogen bonds grouping of cellulose with 4070 cells is called MICROFIBRIL There are many others sometimes run parallel and sometimes twisted like a spiral there are interactions within and between microfibrils diff between fibril and fiber is that fibril is small leads to structure with tensile strength of steel breaking strength is 40160 kg gt great structural strength not unusual to find cellulose in microfibrils making up 2030 of mass of typical plant cells lacking extremely thick cell walls for tree is 6065 of bulk of organism being nonliving cellulose molecules in wood cells are dead as well and thats the only way they can function cell wall of wood is very thick empty at functional maturity stacking them creates internal transport system with tubes next order of structure after cells and microfibril is macrofabril noncellulosic component of cell walls embedded in the lipid bilayer are cellulose synthesizing enzymes bond in complex called rosette has 7 parts glucose molecules delivered to rosettes from cytoplasm side by organelles called dictyosomes small organelles composed of membranous sacs D receive materials within membrane vesicles they fuse with D golgi in animals material is processed D moves to plasma membrane and releases materials into itmany of these vesicles come from ER these contents are used to synthesize cellulose what rosette does takes one glucose molecule and adds it to another construction of cellulose rosette itself drifts due to uidity instead of pushing distance of molecule rosette just moves it microtubules act like a scaffold and pose structure onto the amorphous cytoplasm directs movement of rosette as rosette builds the chain orientation of cellulose molecules to each other has important effect on cell diff between random orientation or parallel both can happen 072315 Cell walls continued cellulose pectic substances hemicellulose Plasma membrane is site of cellulose synthesis glucose polymerized into cellulose there is enzyme complex of 7 single enzyme w7 components cellulose Grows by addition of one glucose molecule at a time Significance to orientation of cellulose microfibersthere is control over what direction the cellulose synthesizing rosette moves scaffolding system in cytoplasm of microtutubles controls it we don t know what controls the microtubules cellulose microfibrils are randomly oriented in some while they are mostly parallel and ordered these make a difference At beginning called T0 what will both look like at T10 First will still be a large sphere since being restrained equally in all directions Second will be elongated vertically since lines are horizontal So placement of microfibrils has pronounced effect on cell shape could be important on cell metabolism cellulose molecules gt microfibrils gt macrofibrils vesicles go from ER gt dictyosome gt vesicles to plasma membrane Not just for cellulose aka pure glucose In addition to cellulose are other polysaccharides like neutral and acidic pectin molecule Cellulosepure glucose hemicellulose on the drawing look like hooks composed of variety of 56 carbonscarbohydrates function allow interactions between adjacent cellulose microfibrils lessening ability for them to slide past each other so more structural rigidity through Hbonding pectin substances modified from single acid not as diverse as hemicellulose but highly hydrophilic allows for more interaction bw adjacent microfibrils there is an intercellular glue between cell walls of different cells allowing cell walls to adhere to each other this is made of pectic substance so common that it is called the middle lamellae as fruit ripens it gets mushy which is from dramatic increase in amount of pectic substance not rotting that is later but pectic substances are produced all plants produce primary cell wall except sperm cells some plant cells have an additional wall called secondary cell wall is formed between primary and plasma membrane since cell membrane is what produces the wall it is because of orientation of microfibrils secondary cell wall usually much thicker than primary cell wall in most cells plant cells that have secondary cell wall they further strengthen it with embedding both cell walls with epoxy resin called lignin it infuses into everything outside Lignin is incredibly strong and resistant to decay even compared to cellulose Lignin is also waterproof Lignified secondary walls are reason for success of many plants last part of ch3 primary cell wall means cell is alive secondary cell wall makes living difficult Living cells wprimary cell wall Primary CW creates problems if there needs to be flow of materials info between cells Structures that look like holes between two adjacent cells All protoplasm between living cells are interconnected These holes are called plasmodesmata Plasma membrane of one cell is continuous wplasma membrane of another cell at least happens during development looking at plant body you have continuum of protoplasm cell at top of tree is continuous a very long distance wcell at the bottom it is important functionally continuum called symplast continuum of protoplasm that exists in living cells of plant body as result of plasmodesmata inside is remnant of ER called desmotubule not important in its function but important in development While presence of plasmadesmata limits independence but doesn t obliterate of cells large macromolecules can t go through those holes just small molecules so there is continuum of protoplasm but also continuum of cell wall and intercellular spaces that continuum is called apoplast continuum of cell wall and cellular spaces Desmosomes are 57 nm in diameter End of chapter 3 Chapter 5 classification scheme based on cell walls easiest to observe cell wall is super important in how cell functions changing cell wall changing cell function Nature of Cell wall 3 types of cells based on cell walls there are simple tissues one cell type and complex tissues many cell types can be cell type or tissue type can find tissues of single cell type 1 parenchyma relatively simple simplest cell wall just primary cell wall never produce 2ndary uniformly thin 1 cell wall looking at potato were storage parenchyma cells important for physical support of the plant part you find them in important for turgor pressure gt water pressure by plant cell with lot of water inside vacuole plants wilt when parenchyma cells lost their water photosynthetic parenchyma called chlorenchyma stem of celery storage potato meristematic most complex specialized cells cells that produce other cells transfer parenchyma specialized for transport of materials across their cell walls collenchyma 6 sclerenchyma lignified cell you re creating cell that s isolated from cells around them can t receive nutrients gt usually cell is then dead cells w greater metabolic diversity the cell with only one cell wall not 2 Cells wsimplest cell walls can have most complex metabolisms so parenchyma is most metabolically diverse cell 9999quot 72415 He clustered Parenchma and Collenchyma together Bc it has a primary cell wall only and set sclerenchyma on its own bc it produces a secondary cell wall that is ALWAYS lignified If you look at secondary cell wall without lignin it is THICKER than primary wall and stronger When you add lignin it becomes enormously stronger and structurally strong END OF EXAM 1 MATERIAL Exam 2 Material 72815 all cells produce by aperical meristem present from tips of parts of shoot or tips of roots Apical meristem gt form primary cellsprimary tissues gt that part is called primary plant body Doesn t have anything to do with simple or complex tissues pea plants rose plants corn plants gt whole thing is primary plant body cells present result from apical meristem LATERAL meristem that gives rise gt secondary tissues gt secondary plant body Lateral meristem also called Cambium singular cambia plural some plants have via activity of only apical meristem some have cells produced by cambia which have secondary body in addition to the primary body no apical meristems at tips of leaves just shoots and roots cambia originate from the middle of primary plant body usually looks like a ring of cells on board he drew plane in the middle of plant and said to look at it from top primary increase in height cambia increase in width add to diameter or girth of stem if you look at a tree you l nd apical meristem at tips of top of tree 2 type of cambia vascular cambia and cork cambium produces bark dead only the cambia are alive once cells mature that it produces they are all dead wood is technical term dead stuff all 3 types of tissues parenchyma collenchyma sclerenchyma make up both primary and secondary bodies doesn t help distinguish which is which read chapter pg 109 arrangement of primary tissues making up primary plant body Primary Tissue Arrangement Epidermis is it a tissue not really its a body part but not an organ but composed of tissue critically important interface boundary between plant and environment intimately involved in controlling what internal environment is in a plant major problems with land plant is loss of water as plants evolved from water plants to land plants the selective pressure to cut down water loss was immense deposition of hydrophobic materials waxes cutin on exterior of epidermis synthesized by plant and secreted outside of epidermal cells forming protective layer especially with respect to water loss you ll nd diff degrees of thickness of wax depending on harsh environments all land plants have this cutin and a loosely organized incrustation in drier environments it ll be thicker thick layer continuous of cutin is called cuticle bene t cutting down on water loss leaves as gas water vapor need 02 for aerobic respiration and CO2 for photosynthesis Stomata are direct result of cuticle enhance gas exchange found in primary plant body of stem especially if plant is green and photosynthesizing Stomatal cells are specialized epidermal cells longer than others like two twinkies in the middle of squares twinkies called guard cellscontact point between both is sealed other way is if its open in a pore called stomatal pore guard cells have band of cellulose micro brils running parallel to long axis of guard cells but not stretching or extending from one end or another creating situation where water enters vacuole pumping osmotically active particles in vacuole how do guard cells assume curved shape ability of them to regulate water in and outusually open during day closed and parallel usually at night path of water loss directly out of stomata transstomatal pathway C02 and 02 come in at the same time bene t outweighs cost or plant wouldn t survive path of water loss directly through cuticle transcuticular pathway Cortex inside the circle simple parenchyma photosynthetic sometimes green so actually chlorenchyma everything else inside the layer of epidermis Vascular Tissue true complexcompound tissues found in both primary and secondary plant body involved in long distance transport of stuff xylem long distance transport of water and minerals dissolved in water parenchyma rare to find collenchyma sclerenchyma is important and is generally of these types fibers type of mechanical or non conductive sclerenchyma tracheids vessel elements all vascular plants have tracheids success of land plants tied to evolutionary experience of xylem in addition to being transport tissue offers physical support to part of plant body that you find on top Fibers and Tracheids more physically supportive than Vessel Elements looking at tracheid and vessel elements whole thing is lignified but T and V are huge players in long distance transport Lignification is problem because lignin is waterproof structural adaptation in both T and V that allow for water transport 2 types of structural things pits region of tracheidvessel element where no secondary cell wall was every lignified and act as conduit for water movement pit membrane not frictionless if one pit on once cell corresponding pit on adjacent cell found in both T and V tracheas are long and wide with tapered ends another trachea forms parallel but not with ends next to each other water goes through each pit on its way up in tracheids pathway of water from one to another to another etc is solely through pits vessel elements have pits but in addition they also have perforations phloem long distance transport of products of photosynthesis 072915 Vascular Tissues Xylem parenchyma collenchyma sclerenchyma fibers of both xylem and phloem give physical support to plant but difficult to talk about strength of tracheid vs strength of vessel element tracheary elements tracheids elongate and fusiform tapered ends on the surface of tracheids are pits where water enters tracheid from other cells traveling from tracheid to tracheid This cell is dead at maturity Hollow tubepipe is better at conducting water Don t worry about size of tracheidpits Look at book Pits and perforations Each represent regions where water will travel from BUT where pits have dumbbell like shape wprimary cell wall in middle and primarysecondary on either end Pit is region of when cell deposits secondary cell walllignification region that forms pit is protected from that becoming a perforation BUT regions that develop into perforations are digested away so no obstruction at all where there is perforation Water is under negative pressure difficult to talk about strength of vessel elements and tracheids not talking about strength of breaking but how strong is cell to prevent collapse when water tension is placed on it TRACHEIDS are stronger in that they are less prone to inward collapse when water insists on tensionneg pressure Smaller diameter will intake water easier with less pressure than hole with larger diameter tracheid and vessel element Is tracheid with circular border pits able to expand no because so much secondary cell wall and most of cell is dead but you still need water transport since cels arout it are growing so in that region to give water you produce tracheids that are stretchable which are the weakest less secondary cell wall more primary so somewhat stretched learning lesson strength not always best for growing region of plant Imagine that cells have expanded and are as mature as they need to be you dont need the helical tracheids but the circular one allows water to be on more tnsion helical is not as good as transporting water as that plant matures you see tracheids that grow which are less likely to inwardly collapse showed picture of secondary wall on tracheids deposited as rings around long tracheid in between those are primary cell wall so each space in between that is a pit you start increasing secondary wall deposition Types of Pitting on Tracheids A anular straight unconnected circles B helical deposited as a spiral C scalariform looks like a ladder more structural rigidity than helical D reticular one which looks like net over it E circles which one would have greatest resistance to collapse during transport e g which one has most secondary cell wall material E difference in secondary cell wall depositionpattern and difference in when they lay it down when would you see most amount of secondary cell wall deposit when cell doesn t have a need to grow any more 534 shows pic of tracheids and flow of water vs vessel elements pit membrane primary cell wall material as opposed to vessel elements present in xylem B more efficient in reducing friction Having just vessel elements is not always the most beneficial multiple solutions to same problem vessel elements more specialized for transport have pits that exist on lateral walls unlike tracheids short and squat can identify each end properly vs tracheid important because in addition to pits have perforations no primary cell wall perforation is entire hole on top Types of Pits Pitting 5 different kinds of pits important in how tracheary elements function especially during development of plant part Developmental Considerations Phloem Parenchyma sieve elements companion cells allouminou Fibers 073 01 5 Finishing Chapter 5 today doing leaves next at Ch 6 yesterday dealing with primary tissues separate chapter on secondary xylemphloem Primary tissues are those formed directly from apical meristems diff bw shoot apical meristem and root apical meristem Primary results in extension of longitudinal height Nonapical meristem results in increase in diameter of plant parts Primary plant body all tissues produced by apical meristem Secondary plant body trunk of tree 529 different kinds of strange pitting found on tracheids technically can find these pits on both tracheary and vessel elements Differences in pattern of deposition and lignification of secondary cell wall material Terms used to describe those patterns are straightforward l anular region in between rings are primary cell wall and then anked by secondary cell wall 2 3 helical spiral helical pitting 4 sclariform secondary wall material placed on top but placed also on rungs ladderlike 5 reticulate laid down deposited netlike highly branched 6 circular boarded pits the amount of pitting with respect to deposition affects 2 things the amount of primary wall dedicated to transport amount of secondary wall the more of one the less of other as going 16 relative area of transport decreases what increases strength of tracheary element secondary wall cells have to be extensiblestretchable to grow taller 541 when going from b to c cell is dead first one Other cells are getting longer and so is the dead cellWhy because its being stretched not expanding on its own still transports water second cell starts deposition of secondary wall material at a later time can still be stretched once you put down cell wall as in cell 3 you can not stretch cell anymore so secondary material doesn t get deposited until it reached final mature size this pitting also found in vessel elements sometimes store water important cells are sclerenchyma sclerids not too important because not seen much in xylem Parenchyma that associate with sclerenchyma are important because can store water and make it available to conducting sclerenchyma can also store necessary nutrients to provide energy for differentiation series if thing on right box is parenchyma attached to tracheary element would you expect to find pitting on parenchyma no because water can t move through the wall primary wall on parenchyma with high specialization w te but can think of entire thing as primary wall Parenchyma cells around the tracheid cells dont have to be stretched they expand on their own Vascular Tissues Xylem in vascular bundle interior bigger complex tissue Phloem in vascular bundle exterior parenchyma in phloem even more critically important than parechyma in xylem since those cells in xylem are modified or types of sclerenchyma in phloemt hose transport cells are highly specialized and modified parencyhma cells known as Sieve Elements 2 types one type in owering plants unlike xylem where you can find tracheary and vessel elements in same plants 2 types known as SIEVE CELLS found in gymnosperms SIEVE TUBE MEMBERS angiosperms in common when functionally matured they are considered to be alive unlike tracheary elements weird metabolism elongate strange in that during development each sieve element loses its nucleus tonoplast is digested vacuole content mixed wcytoplasm known as sieve areas what difference STM have in addition to sieve areas sieve plates cells control their metabolsim diff between cellstube members loading and unloading aka transport between stm and companion cell specialization in each of the walls when they re in contact dicot when these plants germinate earliest leaves are in pairs distribution of vascular bundles in stem were in ring monocot distribution of vascular bundles is scattered tracheary elements organized in longitudinal series which makes sense since they transport from root to top same for phloem which does long distance transport of photosynthesis Lab corn is monocot not organized in looking at vascular bundle of dicot was sun owerno significant difference iin primary growth of seeing which it issubtle differences but not major in monocots no distinction between cortex and pith so they are together called ground tissue or like matrix tissue looking at vascular bundle there is a very specific arrangmeent of tissues within that bundle will hold 99 of the time You ll always find xylem in a bundle oriented toward center of stem and phloem packet in a bundle facing outward protoxylem tracheary elements cells of the xylem that mature earliest when region of stem that they are found in is still expanding growing always at center end of vascular bundle metaxylemmatures later or when that region is normal or somewhat expanding at edge of stem edge of vascular bundle fibers dense red staining perforation plate cross bars alfalfa dicot scientific name medicago 08 03 l 5 Chapter 6 Leaves Diversity of shape and size Maj or factors affecting sizeshape anatomy Internal anatomy innumerable variations in leaves indicates that there are multiple solutions to the same set of problems problems how to maximize photosynthesis maximize CO2 and O2 inward diffusion minimize water loss epidermal layer consists of cuticle made of cutin almost always hydrophobic downside is that it cuts on gas exchange upper surface ventral or adaxial side or surface lower surface dorsal or abaxial side surface weird reason that it is opposite in leaves 2 environments of upper and lower surface are extremely different greatest amount of sunlight on ventralupper surface this surface most prone to evaporative loss of water can be due to convection so has thicker cuticle Epidermis of lower surface area with structures that facilitate gas exchange aka more stomata also more cuticle as well everything in between both epidermis s is known as mesophyll which is main photosynthetic tissue in a leaf There is enormous variation in how these cells can be arragned based on enviornmental history of plant most common is to have one row of photosynthetic parenchymacollenchyma palisade parenchyma mesophyll generally see loosely packed palisade parenchyma cells with some air space to facilitate diffusion of CO2 allows leaves to ex more main concern is CO2 diffusion when light can penetrate very deeply there are multiple staggered rows of palisade parenchyma This is the leaf equivalent of cortex that is stem Greater number of rows you see makign up PP the greater the light intensity the primary function of collenchyma isnt much photosynthesis as to facilitate gas exchange Spongy stuff is very loosely arranged below FF is aerenchyma photosynthetic loosely arranged to facilitate gas exchange called spongy parenchyma also trichomes cut down water evaporation from plant surfae they are extended epidermal cells slow down air currents going over leaf surface which slows down gas exchange not unusual to have leaves on a given plant that can have multilayered PP based on genetics and environment in addition to this only other important tissue in leaf is vascular tissues intimate association of vascular tissues with mesophyll veins are vascular bundles of leaves for purposes here they are always vascular tissue Xylem always on top of phloem with respect to diff in veins we make distinction between major veins lateral veins minor veins petiole at bottom of leaf if not present leaf is called sessile sessile leaves lack petioles vascular tissue NOT petiole extends into leaf considered main vein major vein given term midrib has more xylem and phloem and supportive cells and fibers branching off main vein could be lateral veins by definition of that minor vein is the vein that ends in the mesophyll minor veins are very delicate if branched veins first part is usually lateral and other branched veins are minor vein coming off major veins is pinnate venation no major vein but looks like palm of your hand and radiating outward in minor veins is called palmate venation figure 623A csxn of leaves of holly top layer palisade parenchyma spongy mesophyll below vascular bundle in the middle xylem on top phloem on bottom called midrib some fibers by staining Figure 625A stuff stained reddish are nucleus and chloroplasts cells seem to be full of chloroplasts and nucleus and cytoplasm so appears to be in no central vacuole looks like that because section is rather thick closer you are to wall closer you are to sites of photosynthesis shows 614A with mesophyll and leaf veins what kind of tracheary element is that cell at the end vessel element single large diameter most leaves we are looking at are dicot leaves monocot leaf has parallel veins 08 04 l 5 Leaves Veins vascular bundles Leaves in different environments venation patterns in leaves dicots grasses etc generally see 2 major kind of patterns doesnt matter if you have petiole or not you see main vein midrib and branching out pinnate venation feather looking other type common in dicots no single midrib for major vein but many of them palmate venation many veins radiating out from central point to show vein he drew circle and divided it in half latitudally xylem on top phloem on bottom exterior of vascular bundle is it midrib major lateral minor the larger the vein the more supportive tissue in terms of sclerenchyma you see supporting it as you go down of fibers decrease midrib gt lateral gt minor and number of parenchyma increase this is all a description for what we call bundle sheath bundle sheath extension conduit for apoplastic movement of water above vascular bundle vein that he drew bundle can travel through cell walls out into mesophyll on top there is apoplastic transport parenchyma on top of bundle sheath symplast drew picture of bundle sheaths throughout leaf they are purely parenchyma this is parallel venation which occurs in monocots dont need to distinguish between midrib and minor important in type of photosynthesis that is efficient at higher levels of temperature Chapter 8 Secondary growth one of greatest ability of plants is that they can produce a secondary plant body allowing them to be long lived and competitive Gymnosperms all are capable of secondary growth Angiosperms Monocots lacking the kind of secondary growth this chapter concerned with Dicots some have them some are herbs when looking at development of secondary plant body there is primary plant body first now secondary pbody plant body is addition to first Cambium developing one means that it eventually will develop another both similar in how they are organized vascular and cork vascular cambium looking at where it will be initiated drew csxn dicot ring of vascular bundles in a circle parenchyma cells become meristematic begin to show activity of cell divisiontwo regions in that circle where you see VC originate cells in the vascular bundles beginning to behave as meristem these cells are always between metaxylem and metaphloem so you see initiation of vascular cambium right between the xylem and phloem specifically between metaxylem and metaphloem it was called a fasicular cambium when do you call it one vs the other you also have parenchyma cells that are in the cortex that begin to behave as cambium since originates BETWEEN vascular bundles you call it interfasicular cambium once the lines all meet up you call them vascular cambium instead of fasicular and interfasicular if you can figure out how to control vascular cambia you can figure out how trees produce wood initials cells that undergo division at least one cell remains initial another differentiates into something else 1 fuciform initial means longitudinally elongate vertical axis gt give rise to components of axial system in 2 plant body a different mitotic divisions with respect to placement of new cell wall parallel to cell wall axis but tangent to surface of stem i periclinal division periclinal placement of new cell wall longitudinal amp parallel to tangent of stem surface ii anticlinal division new cell wall at right angle or perpendicular still longitudinal to surface of stem 2 ray initial somewhat cuboidal not elongate cuboidal gives rise to radial system in 2 plant body cork cambium 080515 vascular cambia originate from fasicular cambia 2 types of longitudinal divisions in cells making up vascular cambia all cells in cambia considered to be initials doesnt matter what group of plants fuciform initial very long in axial dimension periclinal division anticlinal division right angle to tangentsurface of the stem when VC is active producing cells that differentiate into secondary cell secondary phloem is always in exterior VC creates secondary xylem e g wood notes on 2 types of initials and divisions to undergo with placement of new cell wall 08 06 l 5 Fusiform initial gt axial gt 2 xylem gt 2Aphloem ray initials gt radial system Anticlinal gt Fusiform initials gt Ray initials they are short secondary xylem produced more than secondary phloem vessel elements number of vertically stacked vessel dead at maturity tracheids dead at maturity fibers usually dead at maturity parenchyma in most trees that we are familiar with the past 2 years of wood is functioning in the transport of water surprising that though cells are dead a small amount of cells are functioning with secondary phloem produced less than secondary xylem sieve tube members angiosperms vs companion cells sieve cells gymnosperms vs albuminous cells regular parenchyma fibers outer one usually remains as initial than inner one the secondary xylem pushes vascular cambium outward and then secondary phloem which is more on the outside gets crushed very quickly within weeksmonths after its been produced There s a lot of xylem but only a small portion is functional not a lot to look at for phloem functional life of secondary phloem components is much shorter ray initials fill in cracks outside of secondary phloem since there is stress from growth vast majority of trunk of tree cells are dead radial system is for short distance transport of materials RADIALLY important function of rays also really important in short term storage of water if things dry out this is source of water close to vascular cambia rays are also parenchyma cambium are cells that get signaled to be mitotic Vascular bundle PHLOEM on TOP XYLEM on BOTTOM Vascular cambia in middle on xylem side produces secondary xylem and on other side secondary phloem Figure 803B nonstoried VC is a single cell wide storied fusiform shorter no central vacuole in any of these cells universal 813C section through probably secondary xylem you dont see secondary phloem or VC VC is very sensitive to availability of water in the soil temperate area of NA wet springs and then tends to dry out further south when water is readily available tracheary elements formed are wide diameter since water readily available is easier to transport long distances VC responds to this drier environment by producing very narrow tracheary elements 3 types of sections cross section 2 types of longitudinal sections tangential radial section for rays most useful section is tangential section 08 07 l 5 Secondary Growth Chapter 8 Diffuse Porous Wood Ring Porous Wood Heartwood and Sapwood Cork Cambium phellum suberin Inner bark Periderm Outer Bark Chapter 9 Angiosperm Reproduction Diffuse Porous and Ring Porous is exactly what it sounds like If looking at cross section through woody stem you see growth rings seen because of difference in diameter of tracheary elements during growth and water availability at the time wider with abundant water and narrow with scarce water DP and RP refer to distribution of the vessels Pore forestry term that means vessel elements some region with lot of vesselpoor porous wood described as vessels in rings within the wood related to water availability wide vessels readily available less available tracheids NOnring is basically diffuse water more uniformly distributed throughout season looking at wood inside was darker than peripheral region that is functionally significant wood functions structural support water transport from roots to shoot gt they are functioning in terms of physical support but not transferring for water support inside regions bad for plant however sometimes fungi get in that region of wood and it is a good setup for them causing damage to structural integrity or kill the tree to prevent this dump junk into secondary xylem in middle that is no longer transporting water e g noxious substances by doing that plant is creating barrier to fungi establishment region of trunk that is dark gt that is why functioning in physical support but not in water support middle of trunk heartwood darkly colored because of all the stuff that is deposited inside another mechanism of it while being formed look at it radial or tangentially imagine tracheary element and you have living secondary xylem parenchyma alongside it and remember there are pits connected to it this parenchyma begins to synthesize new protoplasm which bulges out like a balloon into tracheary elements puts gunk in there and creates barrier this is called the tyloses protoplasmic intrusions by adjacent parenchyma cells into tracheary elements cutting off pathway to potential infection sapwood the living wood but it is transporting water piling secondary xylem behind itoutward amount of heartwood in middle increases but width of sapwood zone doesn t change all that much sapwood gets converted into heartwood as it widens in secondary xylem you ll find angiosperms vessel elements tracheids fibers parenchyma for gymnosperms in secondary xylem no vessel elements or bers yes tracheids and parenchyma oak for example is thicker and tougher because of number of fibers hardwood is wood with fibers will never be gymnosperms softwood is wood wo fibers sometimes there are some soft woods harder than hardwoods because of thick wall tracheids but hardwood is specific term referring to fibers because some hard wood doesn t have as many fibers you do see differences in width of tracheids many conifers live in cold climates gymnosperms aren t deciduous eg dropping leaves in winter that is adaptive trait to get around problem of having frozen water in soil water presence equals water availability because when water is frozen in soil it is not available to plant looking at conifers they keep their leaves on and characteristics to make up for the water desert for example they don t have vessel elements because they would collapse Cork Cambium structure that produces cells that will form the new external barrier between the plant and environment this takes the place of the epidermis Epidermis is part of primary plant body once you shift into secondary plant body epidermis can t do the job like vascular cambium cork cambium is a single cell layer thick and is much simpler divides so that inner cell always remains the initial produces cells that differ into noninitials into exterior of cork cambium differ into cell called phellum outer cell Phellum cell doesn t deliver secondary cell wall but produces material that isn t lignin but has same effect as lignin very impervious to anything waterproof gas proof but not quite as hard as lignin but known as suberin phellum doesn t expand that much but produces suberin and becomes impervious layer now that becomes epidermis all this process kills the initials thats another diff between cork cambium and vascular cambium ldoesnt produce differences between many tissues 2vascular cambium you can touch and its 100 years old but cork cambium may live for a season or less some parenchyma cells in cortex become meristematic and you see discrete line of cork and everything from cork to outside dies as season goes on Cork cambium the next season then differentiates internal to that previous season s cork cambium exact opposite of what you see in vascular cambium which marches out as tree gets older successive cork cambia get initiated into inside after few years the secondary phloem which is next layer in converts to cork cambium once cortex is gone it s gone Chapter 9 Angiosperm Reproduction Diploid Body vs Haploid body gt heteromorphic alternation of generations in some plants you can tell difference between each body phenotypically when diploid and haploid are visually indistinguishable they are called isomorphic alternation of generations Diploid Body 2n meiosis gt Haploid body n usually in animals called gamete but in plants can be millions of cells big or few cells big Diploid plant body that undergoes meiosis is called sporophyte Haploid body formed via meiosis is called gametophyte middle cells are like gametes because of ploidy but unlike them because of behavior dont fuse called spores so Diploid body sporophyte gt unicellular haploid spores produced meiosis gt spores undergo mitosis and differentiation to lead to multicellular haploid body gametophyte sporophyte called sporophyte because it produces spores via meiosis gametophyte produces gametes via mitosis produce diploid called sporophyte this entire cycle called alternation of generations because that is one generation because alternation between sporophyte and gametophyte 08 l 0 l 5 sporophytic part of generation of life cycle and gametophytic part plants that we are familiar with are phenotypically different at each stage so we can tell difference e g they exhibit heteromorphic alteration of generations you see the simpler life cycle in algae where sporophytic part is indistinguishable from gametophytic part not until evolution of simple land plants that you see heteromorphic alteration Sporophyte gt Spores gt Gametophyte n gametesgt young sporophyte gt sporophyte arrows mean produces or producesreleases or producesretains 2n meiosis mitotic div multic haploid body no mitotis fusion A diploid for land plants only some cells go through the sporophyte cycle they are called sporocytes housed in sporangium where sporocytes exist to go through meiosis Sporophyte 2n Sporangium ia plural 2n Sporocytes 2n Spores n haploid released into environment pollen not all spores form the same type of gametophytes angiosperms you see diff types of spores be careful cant call them male or female dont even use that with anything dealing with sporophyte 2 types of spores diff in size one big one small so called it megaspore and microspore Megasporangium retained gt Megasporocyte gt Megaspore gt megagametophytes ONLY PRODUCES EGGS Microsporangium gt Microsporocyte gt Microspore gt microgametophyte ONLY PRODUCES SPERM Gametophyte n gametangia seen in some land plants hold gametes when they are produced but they are not considered present in owering plants gametes diff from spores because of how they behave spores undergo mitotic divisions to make gametophytes gametes are haploid like spores but diff undergo syngamy and karogiamy fuse cytoplasm of sperm and egg and nuclear material thats how you end up wit sporophyte cant tell diff between spore and gamete apart from ploidy level gametophytes are unisexual in owering plants e g male and female you dont see in one gametophyte production of both can have many gametophytes on same plant but not one single gametophyte producing both if cant see diff between microspore and megaspore means they are bisexual gametophytes starts colorcoding 2n red in red he draws microsporangium in red rectangle 4 microsporocytes inside says they undergo meiosis then now have haploid microspores 16 then draws dotted line because variability but on left draws big microspore in whtie because haploid with mitosis instead of dividing just draws cell wall between both but cells retained within original microspore wall one cell known as generator cell other as vegetative cell generative cell then undergoes single mitotic division cell wall drawn between half of the already halved cell each of those is a sperm vegetative cell still existsthat sperm is the microgametophyte whole circle with one VC and 2 S is a pollen grain in most plants they release pollen into environment in 3 cell stage few do it as half that later divide but we talk about just microgametophyte e g pollen e g vc s s lands on part of plant that produces tube out of VC allowing sperm to enter and fertilize egg these occur in owers you see stamens consists of filament and anther both are diploid if you take the drawing with 16 microspore in microsporangium and hook it onto anther you can just call the sporangium the anther it is attached to filament so pollen grains produced in anther male gametophytes produced there ANTHER MICRO SPORANGIUM erases and starts another drawing Red big red rectangle draws one megasporocyte within it 08 1 115 Outline Angiosperm Life Cycle cont Megasporangium megasporocyte megaspore megagametophyte polar nuclei antipodals syndergids egg cell embryo sac nucellus pollen grain vegetative cell generative cell sperm pollination double fertilization endosperm zygote Embryo seed development globular stage suspensor heartshaped stage torpedo stage Endosperm vs cotyledons Seed coattesta mature male gametophyte made of 3 cells vegetative cell and 2 sperms and the cell wall of the microgametophyte draws rectangle again dipolid cell goes through meiosis called cyte in this case megasporocyte will eventually give rise to gametophyte so draws box which says megasporangium circle inside called megasporocyte diploid so everything 2n so far spoangium and everything it contains megasporocyte undergoes meiosis no change in nature of megasporangium but within it now are some haploid cells new box same thing 4 megaspores produced which are haploid THEN 3 of them degenerate left with one functional megaspore for nutrient driven selection so they become nutrients then erases the 3 and just leaves one circle orange saying there is one functional megaspore n they undergo mitotic divisions since haploid third rectangle goes through mitosis end up with structure that has 8 nuclei in 7 cells so one cell is binucleate every one of them is haploid draws big orange oval central cell which has 3 bonified cells at one end called antipodals on the other end you have 3 cells of 2 types One large cell anked by 2 smaller cells Small cells are called synergids 2 In the center egg cell In center of oval there are 2 nuclei called polar nuclei so that entire orange circle big one is called mature gametophyte still in the megasporangium Mature gametophyte ALSO CALLED embryo sac the megasporangial tissue is called NUCELLUS as embryo grows within the embryo sac it is at expense of nucellus can also call the entire thing ovule which is not just the embryo sac but also the nutritive tissue ovule embryo sac nucellus this is not same thing as a seed say you have that entire ovule is ready for fetrilization and the mature pollen grain with a tube cell and sperm cells draws big tube part of mature male microgametophyte aka pollen grain which sticks into the big nucellus Delivers 2 sperm nuclei fall within cytoplasm which is behind them 2 The sperm cell enters the synergid and then traveling to region where 2 polar nuclei are present other nucleus enters second synergid but THEN goes into adjacent egg cell then the 3 nuclei in middle FUSE into single nucleus which becomes TRIPLOID CAN CALL IT ENDOSPERM NUCLEUS eg one sperm 2 polar nuclei the egg cell in right side middle becomes bonified zygote Angiosperms go through process called double fertilization what about the antipodals on left evolution holds for fewer cells possible every cell thats not absolutely necessary is discarded no one really knows what they are there for some people think its a polarity thing for growing pollen tube to enter in right synergids exist but wither away eventually the only important thing is developing zygote and endosperm synergids are last doorway to make sure it is sperm from same species eg gatekeeperprocessor double fertilization one sperm 2 polar nuclei and fusion of second sperm egg cell to make zygote can call the right 3 cells the egg apparatus 2 synergids and 1 egg cell erases cell and draws rectangle with nucellus and big endosperm circle 3 antipodals on left 2 synergids on ank of big egg cell basically 2n n 2n so 3 generations egg cell will supply nutrients to sporophyte of next generation called it a lunch box Now going to cover what happens to zygote on the right All mitotic from here on out this is earliest development of diploid sporophyte Suspensor is always where embryo is contacting with nucellus at right edge of endosperm drew grid like thing looks like a mess no good shape We call this stage a globular stage Suspensor is earliest part of embryo to differentiate into something recognizable goes through many divisions pushes embryo embryo proper into the endosperm which is supplying nutrients for embryo and also suspensor We are now in heartshape stageFirst stage globular was first differentiation of suspensor embryo proper looked like glob Looks like shtail thing next stage is torpedo stage still have long suspensor stage then a little nub then a big hook tube looking thing with 2 hooks that nub thing is a future root called radical the two hook things are called cotyledon before that is hypocotyl future stem 2 things after it is cotyledon not future leaves short life span in the little V is shoot apical meristem suspensor eventually withers away and dies everything else from that structure functions in the future it is diploid Endosperm development first starting with single triploid nucleus within central cell first thing you see is free nuclear division means that you have division of nuclei without any partitioning of any cytoplasm aka no cytokinesis you end up with coenocytic state some of the nuclei then partition into cells then you have CELLULAR STAGE e g partitioning of cytoplasm around SOME nuclei that tends to be more stable will be used later for source of nutrition lST ENDOSPERM TO BE UTITLIZED FOR NUTRIENTS IS THE COENOCYTIC STAGE for developing embryo As embryo develops thats where it gets its nutrients from 0813 skipped 0812 chapter 9 drawing structure of the ower stigma style ovary aka fruit carpalpistil is one and the same but is the entire thing ovary gt fruit you see change in ovary wall 3 layers total called PERICARP wall of ovary l endocarp derived from carpal inner layer in some can be tough layer stone of peach e g removing itcracking it open if you look inside you find ovulesseeds 2 mesocarp middle eshy part of fruit function is mainly for dispersal 3 exocarp skin or peel of fruit dont need to know about diff types of uorescence in owers In orescence vs ower if you have sun ower it is not single ower it is collection of ower if you take outermost parts and look at them you will see yelloworange petals that part of ower has in uorescence that only has stains getting to middle is where you see stains if you look at them before they are mature those parts of collection of owers contain just carpals in uorescence in general is a collection of owers in particular pattern way to define in uorescence organized collection of owers that may appear to be single ower but it is not is functional organization of group of owers but when you pick out a petal you realize its the part of an independent ower if that s the case what you think are sepals are actually called brachs common in plants that grow in cold climates same general group as blueberries one adaptation of these owers is to warm air around it allowing volatile substances to be releases and attracting pollinators inside gets warmer than outside in cupshape owers 907D if ask about 910 asking what it is in life cycle term can put sporangium or microspore or anther eventually produce microgametophytes so whole thing is collection of microsporangia will produce pollen and be released to accomplish pollination microgametophytes transferred from msporangia to region where megasporangia were present 910 B each of those things black things develop into functional spore endosperm used as nutrient for embryo Cotyledon is diploid and part of embryo


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