Molgen 3300 Final study guide
Molgen 3300 Final study guide 3300
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This 11 page Study Guide was uploaded by Brooke Anderson on Saturday May 2, 2015. The Study Guide belongs to 3300 at Ohio State University taught by Alonso/Hamel in Fall. Since its upload, it has received 268 views. For similar materials see Plant Biology in Biochemistry at Ohio State University.
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Date Created: 05/02/15
PLANT HORMONES aka phytohormones Function Since plants can t move they are sessile they need to be able to adapt to their environment extent of branching rootshoot ratio regeneration from damage etc Therefore hormones which drive plant growth are essential They affect cell 0 Division 0 Enlargement o Differentiation Control Usually simple chemicals at within low 908 specifically defined range of concentration too little 391 will not stimulate response too much may not function properly or become inactivedestructive A response nggm can be controlled by two or more hormones either together one will promote activity of other or oppositely one will turn off response while the other aw turns it on Location As opposed to animals which produce hormones in specific glands plant hormones are k localized to full regions ie the leaf not specific cells or cell structure Hormones produced move from one region to another carrying signals that adjust growth and development Action hormones are recognized by a receptor usually on cell membrane and binds to it activating a signaling cascade that ultimately changes gene expression controlling a cell function Classes groups of hormones related by similar base chemical structures Most are transported by nonpolar transport passive diffusion through the phloem xylem o Gibberellins discovered when rice was injected with Gibberella fungus which made the rice grow faster then die GA later found in all plants I Stimulates Organ growth cell division amp elongation by synthesis of cell wall components owering aka bolting which is the formation of a ower stalk from the rosette formed in first year of biennials fruit formation stem elongation Seed germination where GA stimulates alpha amylase for breaking down starch reserves and breaking dormancy I Location amp transport roots apical buds young leaves embryos I M sugar production from barley in beer making spraying of commercial fruits to increase rachis length and fruit size for grapes increase sugar yield in sugarcane o AuxinIndoleacetic acid I Stimulates elongation Induction of adventitious and lateral roots Apical dominance SAM has high concentration of auxin for elongation and primary growth of plant whereas its repressed in axillary meristems which remain dormant When apical dominance is released by removing auxin source of SAM auxin is produced in axillary meristems and branches start growing Allows phototropisms bending towards light I Location amp transport created at tip of shoot only hormone that is transported via polar transport specific transporters auxin carrier proteins control direction of hormone ow through cells travels from shoot tip to in pericycle of roots to promote lateral root growth I Control o Ethylene In roots more auxin more adventitious roots but too high a concentration inhibits root formation In stems more auxin more elongation Phototropisms occur by increasing IAA on dark side of stem causing a bend towards the light Agent Orange a synthetic auxin that can t be broken down by dicots when used in excess and will cause a plant to go in shock losing its leaves then grow itself to death Monocots can break down auxins so did not effect as them significantly Breaks down into dioxin which is toxic to animals In tissue culture to promote root formation in undifferentiated callus I Stimulates Ripening metabolic breakdown of cell wall and starch to sugars chlorophyll broken down to leave chromoplasts bruisingwounding will trigger production Leaf abscission shedding after auxin stopslessens being produced auxin prohibits leaf drop ethylene production will be increased and signal formation of abscission zone where cell wall will break down and leaf will fall off Perception amp response to pathogen attack Note physical damage to auxinproducing leaves lowers auxin levels and triggers abscission I Location amp transport a rapidlydiffusing gas that therefore signals neighbors to produce it speeding up responses 0 Cytokinins work against auxin I Stimulates Cell division Release of apical dominance development of lateral buds I Location amp transport Rapid transport in xylem Made in root tip and travels to shoots to promote outgrowth Therefore lower branches are more likely to form since they re closer to the source of cytokinins I Use In tissue culture to promote shoot formation in undifferentiated callus o Abscisic acid I Stimulates seed dormancy o jasmonates I A volatile that coordinates plant defense among neighboring plants 0 Salicylates like aspirin from willow bark I Stimulates Plant pathogen virus resistance Flower longevity Thermogenesis in Arum owers to volatilize odors that attract pollinators by heat instead of ATPgenerating mitochondrial action ENVIRONMENTAL CONTROL OF PLANT GROWTH NOTE Two types of movement growth movements and turgor movements Nastic response Tropism growth movement Nastic response turgor movement since vacuole turgor pressures size is reversible NOT growth Tropisms o o o o Heliotropism Phototropism length change due to light by sensing extent amp length of light Photomorphogenesis change in shape development due to light Photoperiodism development owering time in response to day length nastic response of leaf ower orientation towards the sun involves phototropin Perception of light 0 Photoreceptors detect and respond to wavelengths of light made up by protein chromophore lightabsorbing center I Phytochrome responds to red 660 nm and farred 730 nm light depending on form Responses 0 Growing away from shade o Photoperiodism detecting amount of daylight o Germination o Photomorphogenesis Activity depends on two conformations Pr inactive off and Pfr active on In dark slowly converts to inactive Pr 0 Pfr form stimulated by red light which results in previously listed responses germination etc 0 PF form stimulated by farred light which prevents previously listed responses prevent germination etc Germination promoted by red light stimulating Pfr form Photomorphogenesis Undergroundgerminated seedlings are etiolated which means they are colorless and apically hooked for protection from dirt These are produced in the dark only farred light stimulating Pr form They have no leaves or mature plastids but the stem elongates rapidly seeking light Upon red light the Pfr form is stimulated and photomorphogenesis deetiolates seedlings generating leaves chloroplasts removing apical hook and slowing growth Shade avoidance Plants in shade receive more farred than red so Pr form stimulates increased internode length growth to get leaves out of shade instead of growing more shading leaves Once in red light Pfr form stimulates leaf growth and inhibits internode growth Photoperiodism night length determinant of owering time Flowering can require a critical amount of darkness depending on the plant 0 Shortday for springfall owering Critical timepoint at least X hours of dark required for owering under 24X of light required 0 Longday for summer owering Critical timepoint under X hours of dark required for owering at least 24X light required 0 Dayneutral where night length doesn t matter for owering around equator 0 Experiments where a long night is interrupted with a ash of light causes the plant to act as though there was a short nightlong day longday plants will ower shortday will not Therefore proving that plants actually sense the night instead of day I Cryptochrome blue light I Phototropin Responds to blue lightUVA for phototropism Also acts in heliotropism Involved in chloroplast movement to maximize light intake in weak light chloroplasts line up on top of leaf cells and avoid damaging strong light chloroplasts line sides of leaf cells avoiding exposure Gravity negative for shoot positive for root 0 Gravitysensing cells Gcells in collumella have heavy amyloplasts that sense gravity When gravity disturbed they trigger a redistribution of auxin to result in growth that orients roots towards gravity and shoot away from it Side that receives concentrated auxin has inhibited growth compared to other side resulting in a bend Touch thigmotropism from wind as well as physical touch from other plants animals or even rain Response aims to create sturdier plants 0 Inhibits elongation o Promotes secondary growth radial expansion Circadian rhythm to synchronize daily repeatable activities 0 Diurnal movements like leaves closing at night and opening at day wood sorrel plant stomatal opening ower opening 0 Light trains the innate clock but does not control it PLANT NUTRITION essential in hydroponic tests if minerals result in physiological or lifecycle changes Macronutrients required in large amounts 0 C 0 H from water air 96 of plant dry weight 0 From soil N nucleic acids protein chlorophyll K ionic balance for osmosis and stomata movement enzyme activator Ca membranes enzyme activator Mg chlorophyll enzyme activator P nucleic acids phospholipid ATP S amino acids vitamins Micronutrients required in small amounts all in soil 0 Cl ion balance photosynthesis Fe photosynthesis respiration B cell wallcell growth and nucleic acid metabolism Mn photosynthesis and nitrogen metabolism also respiration Zn Cu photosynthesis enzymes Ni Mo 0 Dramatic results if plant is deficient in Cu Fe Mn 0 Others may be essential depending on the environment eg cobalt in the desert Na for C4 plants in certain conditions Topsoil the source of nutrients containing minerals from weathered rocks amp dead organic matter Pore space of air and water surrounds solid organic matter and inorganic minerals Nutrient uptake Water and minerals are absorbed through root hairs an active process requiring ATPdriven transporter proteins in root hair membrane that allows entrance against a concentration gradient 0 Nitrogen enters as nitrateammonium N0339 or NH4 o Phosphorous enters as phosphate PO4 0 Potassium enters as K 0 Calcium enters at Ca2 Symbiosis for nutrient uptake using mycorrhizal fungi to take up nutrients and deposit in root cells Endo ones grow inside cytoplasm of root cortex Ecto ones grow outside the root hairs Fertilizer labels NPK 0 High N stimulates vegetative growth and inhibits reproductive growth therefore high N fertilizer is good for lettuce but bad for tomatoes and other fruits Nitrogen cycle for nucleic acids proteins amino acids chlorophylls 0 Atmosphere is 80 N2 but living things require ions of it eg N0339 or NH4 o Nitrogen deficiency in plants is characterized by chlorosis or a loss of chlorophyll which is also marked by anthocyanin accumulation a sign of stress 0 Processes in nitrogen cycle I Fixation reduction of N2 to NH4 ammonium by lightning or soil bacteria w nitrogenase enzyme in association with plant roots These bacteria require anaerobic conditions and ATP can be either symbiotic bacteria or in bacteriaincorporating nodules that are found in legume plants I Nitrification oxidation of NH4 to NOz39 nitrite then N0339 nitrate by nitrifying soil bacteria This is so efficient a process that there s very little NH4 in soil so while plants can take up NH4 as well as N0339 they really only end up having access to N03 Then for cellular processes the plant has to rereduce the nitrate back to ammonium I Assimilation into organic compounds Usually NH4 is incorporated into leaf chloroplasts using ATP from photosynthesis I Ammonification decomposition of Ncontaining waste and extraction of nitrogen bacteria Excess released as ammonium ions Denitrification of nitrate to elemental nitrogen N2 by denitrifying soil bacteria 0 Alternate methods of nitrogen collection carnivorous plants that produce proteases and phosphatase that can digest insects in locations where N fixing bacteria are lacking around roots such as bog plants in acidic environments where Nfixing bacteria can t live I Include sundews ypaper traps and pitcher plants pitfall traps I If nitrogen added to plant will stop digestion production Phosphorous essential mactronutrient o For nucleic acids phospholipids and ATP therefore most likely to limit plant growth I Deficiency marked by anthocyanin accumulation creating dark green leaves stunted stems premature death senescence and dead older leaves 0 From the earth s crust 0 Excess of phosphorouscontaining fertilizer cause algae blooms which are actually bacteria that produce toxic compounds in water 0 Cycle involves bacteria Phytoremediation since no waste system plants can deal with toxic compounds by 0 Turning them into less toxic compounds 0 Sequestering in vacuole less commonly the cell wall 0 Convert and release into the gas form eg arsenic best way because only a tiny effect on the atmosphere s huge volume 0 For these abilities people are using plants to clean up environmental pollution as far as roots can grow and pull up pollutants eg alpine pennycress for zinc and cadmium clean up however only works in moderately polluted areas so that the plants aren t killed LIFECYCLE SYSTEMATIC Plant kingdom terrestrial amp aquatic O O O O Haploid diploid lifecycle Mostly autotrophic Uni or multicellular Cell wall formation Terrestrial plants consist of seedless bryophytes ferns and seedbearing gymnosperms angiosperms also categorized by vascular and nonvascular only bryophytes Theorized evolution Bryophytes photosynthetic with stomata and rhizoidtype roots then ferns vasculature then gymnosperms wood pollen and seeds then angiosperms fruits and insect pollination O 0 Trend through evolution is a reduction in the haploid gametophyte phase Construction of evolutionary history phylogeny 9 phylogenetic trees are built on features the length of branch depending on genetic similarity Plant life cycle 0 0 One diploid 2n structure undergoes meiosis to produce 4 haploid n structures One diploid structure undergoes mitosis to produce two diploid structures One haploid structure undergoes mitosis to produce two haploid structures Fertilization of two haploid structures gametes here produces one diploid structure zygote here In plants haploid gametes are produced from mitosis of haploid spores Haploid spores are produced from meiosis from the diploid sporophyte structure Gametophyte haploid plant body that produces gametes egg amp sperm Dominant generation in nonseeding and nonvascular plants Sporophyte diploid plant body that produces spores Dominant generation in seedbearing vascular plants Fern lifecycle I Haploid gametophyte structure not sexspecific develops from mitosis of haploid spores I Gametophyte produces haploid male vs female gametes which are fertilized to form diploid zygote I Zygote develops into diploid sporophyte generation I Sporophyte generation produces haploid spores through meiosis within spore capsule of sporophyte structure Angiosperms seed receptaclequot have a modified shoot with reproductive purpose Most dominant plant in plant kingdom Reproduction takes place in the ower and can produce fruit I Leaves have evolved into 4 whorls Reproductive o Carpel female stigma style ovary o Stamen male filament anther Nonreproductive perianth o Petals thin modified leaves that serve to attract pollinators o Sepal thick and leaf like to protect bud Flowers with all 4 whorls complete if lacking any incomplete Flowers with both sex organs are bisexual perfect If owers only have one sex organ unisexual imperfect o Monoecious one plant has separate male and female organs eg corn 0 Dioecious male and female organs are on separate plants eg holly o A unisexual ower is always incomplete 0 But an incomplete ower is not always unisexual can be missing petals or sepals instead Lifecycle Dominant sporophyte generation the shoot leaf owers structure has both male and female organs Carpel female organ undergoes meiosis macrosporogenesis to produce haploid megaspores female Stamen male organ undergoes meiosismicrosporogenesis to produce haploid microspores male Within the ovary is the ovule containing embryo sac the female gametophyte and surrounded with cell layers called integuments the site for female gamete formation egg Haploid megaspore undergoes mitosis 3x to produce a cell containing 6 cells and 8 total haploid nuclei 3 nuclei are in antipodal cells no known function 2 are the polar nuclei of the encompassing central cell fertilized to form endosperm one is the egg cell the female gamete to form zygote and 2 are synergid cells to direct pollen tube sperm to egg Anther is site for male gamete formation pollen Contains 4 pollen sacs surrounded with tapetum cells that provide nutrition to sacs 0 Each haploid microspore will undergo mitosis once to produce a second cell within the first a generative cell within the vegetative cell This binucleated stage is the immature pollen grain the male gametophyte The immature pollen grain through wind or insect pollination lands on stigma Generative inside cell of microspore will undergo mitosis to produce two 2 haploid sperm cells male gametes within the vegetative cell now the pollen is mature and trinucleated This mature pollen produces a pollen tube that grows through style to ovary and breaks into egg sac to fertilize ovule Double fertilization unique to angiosperms one sperm gamete fertilizes egg gamete to produce diploid zygote second sperm fertilizes to produce endosperm I Zygote develops into diploid seed which develops into the dominant sporophyte structure I Endosperm 3N nucleus undergoes many round of mitosis without cell division eventually starts to form cell walls to become individual cell walls SEEDS AND FRUITS Progenitor of fruit is the ovary which surrounds the seedgenerating ovule which contains the embryo Embryo development see slides for pictures of each stage 0 Zygote development to embryo establishes I Apicalbasal polarity shoot vs root apical cell is much smaller than basal cell which gives rise to the suspensor which funnels ovule nutrients to the developing embryo ovule gets nutrients from ovary through the ovuleovary connecting stalk I Radial polarity to generate vascular ground and epidermal tissues I Meristems o Preglobular stage is the first divisions of the apical cell into the embryo proper o Globular stage has an established suspensor and embryo has begun to form primary meristems protoderm procambium and ground meristem and starting to create radial tissues 0 Heart stage typical of dicots shows the beginning of baby cotyledons and the SAM versus RAM start to be organized Structure is bilaterally symmetric o Torpedo stage has fully developed cotyledons with a defined SAM and RAM procambium ground meristem cortex amp pith and protoderm Suspensor starts to degenerate 0 Mature embryo is determined with the endosperm is some or fully consumed and the embryo takes up the whole embryo sac The plant tissues are established and the ovule separate from the ovary becoming nutritionally independent The integuments of the ovule harden to become the protective waterproof seed coat 0 Dormancy is established by losing 90 water dessication drying so that seeds can last for years without metabolizing or growing until germination is triggered o Germination is triggered according to several factors I High water triggers germination I Vernalization exposure to longterm cold then warming triggers germination of annuals in temperate climates to prevent germination in harsh winter I Also oxygen light Food can be from fruit or endosperm o In grass grains like wheat and corn most of the food is stored in the 3N endosperm o In coconut the milk is actually liquid endosperm o A fruit is a ripened ovary that forms after fertilization The fruit tissue surrounding a seed developing from ovary wall is called pericarp I Pericarp can be dry or eshy I Fruits can be dehiscent fruit will open to shed seeds like legumes of peas capsules of poppies or indehiscent does not open like grains of corn or nuts or sun ower seeds I Grains are fruit with 1 seed and no pericarp The seed coatfruit wall of wheat is called bran The embryo of wheat is called germ I Simple fruit one fruit formed from one ovary of one ower I Also aggregate and multiple which are formed from several ovaries or several owers like strawberries or pineapple respectively I Some names of foods are misleading Berries are fruit but not juniper berries are actually cones A pine nut is actually a seed not a fruit nut BRYOPHYTES Small seedless nonvascular plants which means no stemleavesvascular roots and no lignin since no xylemphloem Live in watery places for reproduction attach to surface by rhizoids 0 Moss gametophyte has stemlike axis with leaflike phyllodes sporophyte is a stalk topped with a capsule that opens to release spores at maturity o Liverworts gametophyte structure is at and broad called a thallus o Hornworts gametophyte is thalluslike sporophyte stalk is hollow inside and opens to release spores at maturity Male sex organ antheridia female sex organ archegonium Lifecycle is dominated by the gametophyte stage which carries brief sporophyte structure 0 Haploid spores germinate to form filamentous haploid protonema I Protonema buds off to give rise to rhizoids and gametophyte structure giving rise to a large plant connected by the protonema o Haploid gametophyte contains sex organs the male antheridia and female archegonia where the haploid sperm and egg gametes are produced by mitosis The male sperm are agellated and must swim to the archegonia and down a channel to fertilize the egg creating a diploid 2N zygote sporophyte Diploid zygote develops into diploid sporophyte structure a long diploid stalk seta topped by a capsule Inside capsule meiosis takes place to produce haploid spores At maturity the capsule will open and spores will disperse by wind
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