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Lecture Notes 9-12

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by: Molly O'Neil

Lecture Notes 9-12 biol 208

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Molly O'Neil

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Here are the completed skeleton notes from lectures 9, 11 and 12. I filled out all of the definitions and included photos of labeled charts that we went over in class.
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This 22 page Study Guide was uploaded by Molly O'Neil on Sunday November 1, 2015. The Study Guide belongs to biol 208 at Towson University taught by Dr Firestone in Fall 2015. Since its upload, it has received 157 views. For similar materials see Biodiversity in Biology at Towson University.


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Date Created: 11/01/15
Lecture 9 Before class, do the following:  read page 516 in the text  watch: o  review of mitosis  Note the purpose of microtubules (part of the cytoskeleton) and motor proteins. These are a new development! Not found in prokaryotes.  Remember: mitosis is a separate step from cytokinesis. Not every organism does them one right after the other. (I’m looking at you, plasmodial slime mold!) o  review of meiosis  Note crossing over and recombination, which are important because they increase the odds of a single chromosome having multiple beneficial alleles for different genes. This increases the odds of producing offspring with higher fitness than their parents. and define the following vocabulary words:  mitosis = in eukaryotic cells, the process of nuclear division that results in two daughter nuclei genetically identical to the parent nucleus. Subsequent cytokinesis (division of the cytoplasm) yields two daughter cells  meio sis = in sexually reproducing organisms, a special two stage type of cell division in which one diploid (2n) parent cell produces four haploid (n) reproductive cells (gametes); results in having of the chromosome number. Also called reduction division  cytokinesis = division of the cytoplasm to form two daughter cells. Typically occurs immediately after division of the nucleus by mitosis or meiosis  oxygenic photosynthesis  cyanobacteria = a lineage of photosynthetic bacteria formerly known as blue- green algae. Likely the first life-forms to carry out oxygenic photosynthesis  haploid = (1) having one set of chromosomes (1n). (2) a cell or an individual organism with one set of chromosomes  diploid = (1) having two sets of chromosomes (2n). (2) a cell or an individual organism with two sets of chromosomes, one set inherited from the maternal parent and one set from the paternal parent Any questions on mitosis, meiosis, or cytokinesis? 1 2 Before Cyanobacteria No Oxygen: Archaean Cyanobacteria 3.5 billion years ago Photosynthesis CO2 + H2O  sugar and oxygen Proterozoic area  low oxygen, first eukaryotes Phan  start getting multicellularity, getting 100% oxygen in the atmosphere Two bumps that increase oxygen levels: cyanobacteria and algae Campbell Biology 9 edition Archaean Era  No free molecular oxygen existed for the first ~2.4 billion years of Earth's history.  Which groups of prokaryotes would have lived then? Proterozoic Era Transition from Proterozoic to Phanerozoic Eon 3 The Photosynthesizers Cyanobacteria dominate many marine and freshwater environments. They produce much of the oxygen and nitrogen, as well as many organic compounds, that feed other organisms in freshwater and marine environments  first evidence of cyanobacteria: 3.8 billion years ago Red algae (aka Rhodophyta) can be multicellular or unicellular. They are used for a variety of commercial purposes, including nori (the seaweed in sushi) and the thickeners for ice cream and cosmetics. They can secrete calcium carbonate (limestone!), which are the base for coral reefs. In addition to chlorophyll, red algae have phycoerythrin, which is able to do photosynthesis with much less light. This means that red algae can grow at lower depths in the ocean than green algae. Red algae do not have chloroplasts. Their photosynthesis is done by a unique organelle.  Where does most of the U.S. limestone come from?  Indiana because it used to be a great barrier reef, Colorado was coastal, sea sponges, coral, and algae all produce calcium carbonate which is limestone  first evidence of red algae: 1.25 BYA -no chloroplasts but have unique organelles -have multiple pigments including chlorophyll  Where did chlorophyll evolve on the tree? Is it a homology or homoplasy (if it evolved twice)? Cyanobacteria and (red arrow group) 4 It’s both a homology and a homoplasy Tree #1 – evolves once, all can do photosynthesis Tree #2 – evolves multiple times, some can do photosynthesis Tree B shows that photosynthesis evolved multiple times. What data would you need to convince you that tree B is the correct one? -DNA testing (is it the same DNA sequence producing the pigments?) if the DNA was slightly different we would say tree B is correct -Niches – lose photosynthetic traits because they are not advantageous (this suggests tree #1 is correct) -Gain photosynthesis because they’re all in the same habitat or because the niches are similar (convergent evolution) – suggests tree #2 is correct -Do they share other similarities? -photosynthetic pigments evolved multiple times 5 Green algae (aka Chlorophytes) can be single-celled or multicellular. They live in water and wet soils. You may find them in your fish tank. This is where we see chloroplasts for the first time!  first evidence of green algae: 0.9 BYA Volvox: a transition from unicellular to multicellular  can produce sexually and asexually, they’re like a hippy commune of green algae, and individual cells can produce gametes and then reproduce sexually Endosymbiosis Blankenship R. E. Plant Physiol. 2010:154:434-438 RC = reaction center, a key protein in photosynthesis Zea (corn) Cryptomonas (brown alagae) Parphyra (red algae) 6 Chloroplasts DNA is most similar to Synechococous Mitochondria are most similar to acidobacteria We believe that photosynthesis evolved multiple times and also chloroplasts migrated to the other plants once (but they only studied corn and algae) Additional studies suggest endosymbiosis happened more than once (cyanobacteria and green algae) Haploid vs. Diploid Are bacteria haploid or diploid?  haploid Left side is haploid and the right side is diploid Are brown algae haploid or diploid?  For brown algae, which phase is dominant?  diploid phase: 16 cells vs. 100 feet tall, how big is the organism -- Normally you tell if it has the most cells, sometimes you go by the length of the phase Is the non-dominant phase free-living, or does it depend on the dominant phase?  it is free living Is the non-dominant phase multi-cellular or single-celled?  multicellular Complete the Haploid-Diploid worksheet. 7 Info for Exam 1 1. Covers lectures 1-8 (not this lecture) 2. You can bring notes on one side of a 3x5 card. Have your name on the card 3. Bring the 50-question scantron sheet. (not the 25-question scantron sheet) 4. There will be assigned seating. 5. There are multiple-choice questions, definitions with a word bank, and short answer questions. There are phylogenetic trees and a graph. You should be able to: 1. Define the vocabulary words. 2. Diagram mitosis and meiosis. 3. Describe cytokinesis and when it happens. 4. Explain the Photosynthetic Revolution (aka Oxygen Revolution) and which organisms were responsible for it. 5. Explain how Eukaryotes could have evolved via endosymbiosis. (Raven, 10 th edition, Chapter 29.1) 6. Draw the brown algae life cycle. Correctly label which phase is haploid vs. diploid. Correctly label mitosis and meiosis. Lecture 11 l\Before class, read Chapter 30 in the text and define the following vocabulary words:  Leaf = the main photosynthetic organ of vascular plants  Root = an underground part of a plant that anchors the plant and absorbs water and nutrients  Stem = vertical, aboveground structures that make up the shoot system of plants  Xylem = a plant vascular tissue that conducts water and ions; contains tracheids and or vessel elements. Primary xylem develops from the procambium of apical meristems; secondary xylem, or wood, from the vascular cambium of lateral meristems  tracheids = in vascular plants, a long, thin water conducting cell that has gaps in its secondary cell wall, allowing water movement between adjacent cells  phloem = a plant vascular tissue that conducts sugars, contains sieve-tube members and companion cells. Primary phloem develops from the procambium of apical meristems; secondary phloem, from the vascular cambium of lateral meristems  cellulose = a structural polysaccharide composed of B-glucose monomers joined by B-1,4-glycosidic linkages. Found in the cell wall of algae, plants, bacteria, fungi and some other groups  lignin = a substance found in the secondary cell walls of some plants that is exceptionally stiff and strong. Most abundant in woody plant parts.  Cuticle = a protective coating secreted by the outermost layer of cells of an animal or plant 8  Sporophyte = in organisms undergoing alternation of generations, the multicellular diploid form that arises from two fused gametes and produces haploid spores  gametophyte = in organisms undergoing alternation of generations, the multicellular haploid form that arises from a single haploid spore and produces gametes. A female gametophyte is commonly called an embryo sac; a male gametophyte, a pollen grain  mycorrhizae = a mutualistic association between certain fungi and most vascular plants, sometimes visible as nodules or nets in or around plant roots The Challenges of Land Why move onto land? -no competition (more space- plants will live in more extreme environments) -no herbivores -more sunlight -no pathogens -no parasites What new issues would green algae have to deal with when becoming terrestrial? -more extreme temperatures -need to hold yourself up on land -easy to lose water (no problem with that on a marine environment)  plants can keep water in by their cuticle layer/waxy layer – prevents water from evaporating – water can only evaporate from pores which are stomata – stomata open and close all the time, the stomata let air and water in and out through  with a big surface area, it will be easier to lose water -get fatter – reduce the surface area to volume ratio Keeping the water in How do land plants keep from losing water? -cuticle -stomata (allow water out in a controlled fashion) Algae – 2 cells moss – 10 cells many cells -Getting fatter can reduce water loss 9 -With high humidity, water won’t move out as fast – a harrier plant will have less water movement than a non-hairy plant – by this logic plants in the tropic will be smooth Moving the water up Tracheophytes are tall. Their aerial parts do not have contact with water. How do they get water? -Tracheophytes are land plants with xylem and phloem -tubes, plants can no longer use diffusion, need xylem (water) and phloem (sugar) -Hydrogen bonding make chain of H2O – evaporating H2O pulls chair up Why are roots so hairy? -need roots and mycorrhizae -mycorrhizae served as a root system -roots increase surface area to volume ratio so that you can increase the amount of water coming into the roots Sex on land: harder than it looks Look at the diagram of the green algae life cycle. Where are land plants going to have difficulty? -at fertilization land plants are going to have difficulty -gametes need to be able to swim to each other -spores need to be able to swim away from the sporophyte to disperse, will not work in land plants -mosses are in really wet areas – can swim -ferns are big, and make gametophytes who need to live in wet areas – gametophytes only grow in wet soils like where the mosses are growing – gametes can swim -gymnosperms and angiosperms – the pollen transports the sperm, so they don’t need to swim – not required – these plants can live in really dry areas 10 Mosses- spores can still swim because they are in a wet area Ferns – transported by wind instead of water Angiosperms and Gymnosperms – the spores don’t disperse at all Dispersal agent for Angiosperms (also have fruit) and Gymnosperms – seeds for both Standing up for yourself Why did taller plants have an advantage? -Taller plants can get sunlight away from the competition, they are better competitors -plants can get taller because of their … Xylem and phloem and fiber cells  Wood is a secondary cell wall – it has lignin and has lots of cellulose (cellulose – a fiber) and is made by cellulose (rebar) and concrete (lignin) - very few things can break down lignin 11 club moss Selaginella Ginkgo- big leaves with lots of veins for catching sunlight, bigger is better – how we got leaves 12 Let’s Review Review Cuticle – essential from getting to land (4 common ancestor/node) th Xylem and phloem – thcommon ancestor Stems and roots – 7 common ancestor True leaves (leaves with more than one vein in them, one vein is consider a pseudo leaf) – 8 common ancestor Pollen – 9 common ancestor (need seeds and pollen) th Wood – 9 common ancestor You should be able to: 7. Define the vocabulary words. 8. Describe the four challenges plants on land have to deal with. Describe the adaptations that overcome these challenges. 9. Explain how water moves up to the top of a redwood tree. Explain why it is advantageous for plants to be tall. How do they achieve Lecture 12 Before class, do the following:  read Chapter 31 in the text  watch the following videos: 13 o  You do not need to memorize everything in this video. It has extra details, which can be useful for you to understand the material from lecture. o  and define the following vocabulary words (not all of these are in your text book):  xylem = a plant vascular tissue that conducts water and ions; contains tracheids and or vessel elements. Primary xylem develops from the procambium of apical meristems; secondary xylem, or wood, from the vascular cambium of lateral meristems  tracheids = in vascular plants, a long, thin water conducting cell that has gaps in its secondary cell wall, allowing water movement between adjacent cells  vessel elements = in vascular plants, a short, wide water conducting cell that has gaps through both the primary and secondary cell walls, allowing unimpeded passage of water between adjacent cells  primary cell wall  cellulose = the outermost layer of a plant cell wall, made of cellulose fibers and gelatinous polysaccharides, that defines the shape of the cell and withstands the turgor pressure of the plasma membrane  secondary cell wall  wood = the innermost layer of a plant cell wall formed by certain cells as they mature. Provides support or protection  pit pairs - two pits occurring opposite one another in the walls of adjacent cells of many higher vascular plants and acting together as a structural and functional unit  torus  only in tracheids, seals broken cells off - plug-like structure that seals off the opening between adjacent cells and stops the embolism from spreading  phloem = a plant vascular tissue that conducts sugars, contains sieve-tube members and companion cells. Primary ploem develops from procambium of apical meristems; secondary phloem, from the vascular cambium of lateral meristems  sieve cells (aka sieve tube members) - an elongated cell whose walls contain perforations (sieve pores) thatare arranged in circumscribed areas (sieve plates) and that affordcommunication with similar a djacent cells.  source = any tissue, site or location where a substance is produced or enters circulation (eg: in plants, the tissue where sugar enters the phloem)  sink = any tissue, site, or location where an element or a molecule is consumed or taken out of circulation (eg: in plants, a tissue where sugar exits the phloem)  stomata = generally, a pore or opening. In plants, a microscopic pore on the surface of a leaf or stem through which gas exchange occurs  stomatal crypt – large chambers in the mesophyll, covered with an epidermis that contains stomata as well as trichomes (hairs) that project into the crypt  P-protein (aka P-slime) - (??) 14 Tracheids  tall and thin, has a torus, can have cells damaged and deal with it faster than vessel elements, when air gets in you would only lose one cell Vessel Elements  short and fat, have a hole in the bottom that goes through 1° and 2° cell wall, no nucleus, no plasma membrane, just like a straw, dead in maturity, nothing but 1° and 2° cell wall -water moves through plants through negative pressure, from being pulled up through the top Moving Water What cells are involved in moving water? How are they similar? How are they different? Tracheids Both Vessel Elements -tall and thin -1° and 2° cell -short and fat -hole goes through 2° only wall -hole goes through 1° and 2° cell -no hole in primary cell -move water wall wall -dead at maturity -make up xylem -has a torus (large pores) -looks like a straw – cells are dead at maturity, no nucleus or organelles – passive tubes What do these two types of cells look like? Tracheids Vessel Elements What aspects of the cells will affect the flow rate of water? Which type of cell will have a higher flow rate?  vessel elements 15 -Water moves through plants through negative pressure – it’s being pulled up through the top -Big holes and no 1° cell wall = less resistance for tracheids - if there is enough water  larger tube will have a faster flow rate  means vessel elements will have the faster flow rate In dry environments, surface tension pulls the water to the surface of the roots with the same strength as it pulls the water to the surface of the leaves. This tug-of-war can cause the chain of water in the xylem to break, forming an air bubble. If it isn’t stopped, the air bubble will expand throughout that particular column of cells, making them useless. In this situation, is it better to have tracheids or vessel elements? -Tracheids would be better because there would be a slower rate for it to be lost -Tracheids would slow the water down so you wouldn’t lose it as fast -Tracheids would seal up really fast if an air bubble occurs because of torus -water is really hard to come by in the winter, rings on tree in the winter, cells formed in the winter as smaller than cells formed in the summer, Moving Sugar Which cells are used to move sugar? -phloem tissue -sieve cells What is the difference between sieve cells and xylem cells? Sieve Cells (phloem) Xylem (tracheids and vessel elements) Alive Dead at maturity Usually had a companion cell No plasma membrane Has a plasma membrane No nucleus Not many organelles, but it is alive Can have a hole through the 1° and 2° Nucleus cell wall, possible Does have holes but things still need to be transported through the plasma membrane Active transport of sugars Water is pulled through the plant. Is sugar pulled or pushed through the plant? How does this happen? Water is pulled from the plant Active transport  being pushed – the sugar is taken from a leaf and then actively pumped into the phloem -sugar moves in, cells have lots of sugar, high solute concentration -sink, something that needs the sugar (roots) -sink actively pumps the sugar out of the phloem -sugar has been moved out, now a lower concentration of solute so water will move back in 16 -hypotonic solution  movement of water from a high to low concentration, ex: when water moves into a bag of sugar or cell -if there is a cell in a pure water environment, water will move into the cell and the cell will explode. Cells living with pure water need a cell wall or something to prevent that from happening What is a “source” for sugars? What is a “sink”? Are the sources and sinks in a maple tree different in the early spring vs. in the summer? Source  leaves, roots a source for the spring Sink  sugar storage, potato, flower (nectar), roots are sinks during the summer or where photosynthesis is occurring, leaves are a sink in the spring – something that needs the sugar – will actively pump sugar out of the phloem Source and sink can change depending on season Summer vs. Early spring  no leaves when you’re tapping a tree for maple syrup because there are no leaves February/March – start pushing sugars up the roots Based off of the drawing… A – moves down, from the source to the sink B – moves up C – moves down D – moves up, from the source (leaves) to the sink (flowers) Note: xylem is always easy, it always moves up, may not always move up very fast but it does move up What is P-slime? -in the phloem -clogs the phloem up of important materials -slime – long strands of protein -prevents the loss of sugar water if a phloem cell is broken (a really good adaptation, similar to the torus in the xylem) Ex: thinking of long hair in a back tub, water movement is going to be very slow because of the air, hair will go in the hair trap so that water clogs up the tub Living at the extremes What challenges do desert plants face? What adaptations allow them to live there? -extreme temperatures -dry, lack of water  adapt by making the pores/stomata smaller or having fewer stomata // only have leaves when its wet // get fat (surface area/ volume ratio) // get fuzzy – want hairy plants to keep the humidity inside of the plant, slow down the movement of water out of the plant // more tracheids and fewer vessel elements // stomatal crypt – hairs are 17 like wearing a jacket, insulates humidity and slows water movement, the crypt is like standing out of the wind -cacti hold their breath during the day What challenges do tropical plants face? What adaptations allow them to live there? -very wet, humid – hard to evaporate water, can have more stomata, have more vessel elements because it makes it easier for water to move up // not fuzzy, won’t prevent evaporation // thin leaves, only a few cells wide // big leaves help with evaporation and collect more light -very shady – big leaves -many parasites, predators, pathogens – chemical warfare, caffeine is toxic to insects // produce lots of seeds, move the seeds very far away What challenges do Maryland plants face in the winter? What adaptations allow them to live here? Cold, dry, cold hair doesn’t hold humidity PPPP Nepenthes attenboroughii Eating rats – predator Can do photosynthesis – producer 18 Dodder Not photosynthetic, not a producer Wraps around a stem and punctures it, goes inside the phloem and sucks the sugar (a parasite) Welwitschia 2 leaves in its entire life, 100’s years, one of the oldest seed plants – a producer, makes its own sugars 19 20 21 You should be able to: 1. Define all the vocabulary words. 2. Explain how water moves through a tree. 3. Explain how sugars move through a tree, and describe how it is different from water. 4. If given a new type of environment (hot, cold, wet, dry), predict which adaptations would allow plants to live there. Explain how those adaptations would overcome the challenges of that environment. 22


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