BIOL 371 Midterm 1 PDF

BIOL 371 Midterm 1 Theme 1: What is an Organism? - It can consist of a single cell or multiple cells - It's part of the living world hierarchy - Single celled = bacteria - Multiple celled= plants or animals Levels of Living world Ecosystem→ community → population → organ...

BIOL 371 Midterm 1 Theme 1: What is an Organism? - It can consist of a single cell or multiple cells - It's part of the living world hierarchy - Single celled = bacteria - Multiple celled= plants or animals Levels of Living world Ecosystem→ community → population → organism —>organ→ tissue→ cells→ molecule → atom The major divisions of living world are defined by different characteristics such as: 1. Bacteria a. Single celled with no nucleus b. Gave rise to mitochondria 2. Archaea a. Similar to bacteria 3. Eukarya a. Has a nucleus b. Can be single or multicellular What are Eukaryotes? - Has nucleus, has a membrane organelle and has large 80s ribosomes - It has many features like : - cytoskeleton : supports the cell shape and has protein fibres to control membranes and the shape - It enables eukaryotes to engulf food particles → phagocytosis - Has microtubules → hollow tube formed from tubulin dimers - Has microfilaments → double helix of actin monomers for movement and transport - Has intermediate filaments that are made from proteins for support - It also has two elements allowing the cell to move - Cilla → shorter and made from many cells to help move fluid or the cell - Flagella→ which are long and works in paris to propel the cell forward - Endomembrane system  - This is a collective term for nuclear envelope, lysosomes, golgi apparatus, vacuoles, and the endoplasmic retritum - They work to compartmertive the interior of the cell to increase available surface area for synthesis - Has multiple, linear DNA - Involves gametes fusion - Plastids found in plants Prokaryotes - Single loop of DNA - Good for rapid replication but gene regulation is dimple - 70s ribosomes (like mitochondria Why are Eukaryotic linear chromosomes? - Allows for the complex gene regulation - Allows for cell differentiation and production of tissue types - All the chromosomes replication happens in parallel What is a Mitrochornaia? - Site of oxidative phosphorylation - How cells use food to make ATP - Eukaryotic cells have chloroplast for photosynthesis to get energy - Increases the Surface area for energy production Sexual reproduction → only eukaryotes - Fusion of haploid gametes form two parents to form a new individual genetically different from either parents → Vertical transmission Endosymbiotic Origin of Mitochondria and Plastids - Evidence (form of lateral transfer) - Circular DNA - Independent fission → remove mitochondria or plastids from the eukaryotic cell therefore it cant produce new ones - Size was smaller than eukaryotes - Double membrane - 70s ribosomes (not same as eukaryotes) Primary Hypotheses 1: - A heterotrophic eukaryotic cell engulfed a aerobic (oxygen using) proteobacterium to form a mutualistic relationship which became the mitochondria Hypothesis 2:  - A heterotrophic Eukaryotic cell engulfed a photosynthesis cyanobacteria which becomes the chloroplast Two alternative scenarios for evolution of final form of eukaryotic cell: 1. Archeaon developed a endomembrane system and then got a mitochondria 2. Archeoa engulfed the mitochondria and then developed the endomembrane a. This makes more sense because mitochondria would have provided energy to make other organelles. Horizontal gene transfer : prokaryotes gene transferred to eukaryotic nucleus Secondary Endosymbiosis: - A heterotrophic eukaryote cell engulfed an autotrophic eukaryotic? Cell sizes : - Eukaryotes are larger than prokaryotic cells - Cube- square relationship shows that an object grows larger, its volume grows faster than the surface area → not linear → liming relationship - Rate as which materials enter and exit is SA - Rates at which gases and nutrients are used and wasted is the volume - Smaller cells can exchange materials more effectively - Constraining relationship → diffusion or active transport allows for exchange across membrane and work better in very short ranges - Membrane floods in the mitochondria / golgi and plastids allows for greater entry and protein production Types of Multicellularity 1. Simple : involves cell adhesion, cell to cell communication, no bulk flow a. Bulk flow is movement of fluids and gases through channels b. Examples : i. algae like volvox are colonial organisms where cells function as collective unit ii. Slimes molds forms aggregates of cell that act as a simple cellular organisation 2. Complex: cells adhere, communicate, differentiate and composed of many cells with specialized functions a. Arose independently at least 6 times 3 origins of multicellular life 1. Symbiotic theory  a. Different unicellular organisms that live together forming a symbiotic relation and specialise together to be a single organisms 2. Syncytial theory a. One cell divides into multiple cells with cytokinesis and differentiates 3. Colonial Theory a. Begins with a flagellated unicellular of same species who form colonies and differentiate Evolution of Multicellularity - Cyanobacteria , the great oxygenation event - Gave rise to oxygen levels due to photosynthesis - Helped complex animals - Simple Multicellularity appeared at the end of the event - The 2nd rise showed the complex Multicellularity Cell adhesion - when cells stick together to form tissues 1. Tight junctions help penetrate cell membranes, fix cells and prevent movement of cells 2. Anchoring junctions helps link cells together and to the microfilaments Differentiation- when cells becomes specialised for certain functions Evolutionary models: - Begins with flagellated unicellular organisms - Cells needs to be able to adhere to one another - Be able to divide up to spelt tasks - Cells need to learn to communicate Why is Multicellularity important? - Unicellular organism carries out all functions in a single cell but multicellularity allows the tats and functions e be split up Advantages of multicellularity: - Division of labour and economy of scale - Has increases size - Helps avoid predators - Can exploit newer laces, reach upwards - Increases in feed opportunities - Has produced internal environment - Cells can specialise - Has new metabolic functions - Has enhanced motility - Can share information with other cells - Increases traction in wind or current Disadvantages: - Has predator/ prey or host/parasite interactions  - Increases opportunity for diversity in function and niches Some challenges of being large: Intercellular communication - cells being able to communicate with one another - Diffusion is short range so useful it cells are close together - Gap junctions help in communications - Bulk flow helps with gas or liquid movement - Nerves Must have cell adhesion As it gets larger= SA gets smaller relative to V Structure and support - Terrestrial animals can only get so big - Smaller animals lose heat faster - Smaller animals have a higher BMR while larger has less mass-specific metabolic rate Adaptations for increasing Surface area 1. Gas exchange a. High folds to pack greater surface area into smaller volume 2. Nutrients absorption a. Has villi of small intestine to increase SA for absorption b. Needs bulk flow 3. Filtration a. Allows for high SA in capillaries What is Homeostasis? - Helps defend cells against hostile environment - Extracellular fluid is all the fluids outside the cell → must be kept stable - Intracellular fluid is all the fluids inside the cell Reproduction and Growth - Must be able to produce new bodies - Unicellular → fission or mitosis - Multicellular → fusion of gametes Characteristics of animals : - There is triploblastic (4 types of tissues) that arise from three embryonic germ layers - Muscles - Neural - Epithelia - Connective -Has extracellular matrix and basic matrix -has collagen which is an extracellular fibrous protein for connective tissues Theme 2- Animals Opisthokonts → Kingdom and fungi - Animals, fungi, choanoflagellates What are choanoflagellates? - Unicellular opisthokonta eukaryote - Sessile - Reproduces asexually - Closest to animalia among the opisthokonta - They have a collar around the flagellum that has contractile microfibrils - Has choanocytes in porifera (spongues) - Consumers of bacteria - Unicellular filter feeders Origins of Opisthokonts = ancestral animals descended from a colonial choanoflagellate Opisthokonts ANIMALS: - Multicellular eukaryotes - Chemoheterotrophic - Extracellular digestion - Has no cell wall - Motile (has some type of self-direct movement) - Oxidative phosphorylation for ATP - Sense and responds to the environment - Diploid stage is dominant → has 4 diagnostic characteristics - Developed from a blastula and underwent gastrulation - Cell membrane contains cholesterol - Has certain extracellular matrix such as collagen - Has cell- cell junction (tight, anchoring, and gap junction) Archaeplastida PLANTS - Multicellular eukaryotes - Photoautotrophic → fixes inorganic carbon using light energy - Has cell wall - Sessile - Haploid (gametophytes) alternates with diploid (sporophyte) Difference between Opisthokonta and Archaeplastida → In plants (Photoautotrophic) - Has cell walls for cell shape maintains and protects cell - Has large vacuoles, which produces turgor against cell wall - Has chloroplast - Don't need to move but can be moved through growing up/down laterally, disperse by pollen/seed, phototrophic → In animals - Can be moved (mobility) or can move themselves (motility ) - Chemoheterotrophs - Most be mobile in order to get foods - Motility characteristics - Muscle - Sense and cephalization - Nervous, digestive, excretory, and skeletal systems - Locomotory - High metabolic rate - Some can be sessile - Diploid as dominate stage What is a clade? - A monophyletic group composed only of taxa with common ancestors sharing synapomorphies (shared derived, homologies) Divergent evolution is closely related species that may have variation in traits. Conversenget evolution is unrelated species that have similar traits. Cladistics help estimate the evolutionary relationships based on shared derived characters and can be used to make predictions. - Phylogeny that requires the least amount if proposed evolutionary change →most parsimonious Classification of Linnaean → more shared common ancestor means more exclusion The Cambrian Explosion - First diverse fauna of large complex multicellular animals - First fauna with eyes and jaws - Homeotic genes → genes which regulate the development of anatomical structures - Represents evolutionary radiation of Animalia Animal Classification 1. Asymmetric →no major axis of symmetry  2. Radial symmetry → body can be cut into identical pie segments, no left/right or front/back 3. Bilateral symmetry→ body has mirror-image left-right symmetry Animals Characteristics: - Body cavities→ coelom - Acoelomate : no cavity enclosing the gut - Pseudocoelomate : cavity enclosing the gut lined with mesoderm on outer side, no inner side - Coelomate : gut suspended in cavity lined with mesoderm on both sides - Diploblastic animals → two embryonic tissue layers, endoderm and ectoderm - Triploblastic → three embryonic tissue layers, endoderm, mesoderm, and ectoderm - Bilateraians divided into - Protostomes : first opening in embryo becomes mouth - Deuteromoes : opening becomes anus first - Metameric segmentation (repeating) - Chordates, arthropods, annelids Phylum Ctenophora : comb jellies - Bridal symmetry Phylum Porifera ( sponges) - Asymmetrical - Sessile as adults - No nerves, filter feeders - Choanocytes flagellar actions - Suspension feeders Phylum Cnidaria ( jellyfish, coral) - Radial symmetry - Diploblastic Cnidocytes and Nematocysts - Shared derived of Cnidaria - Used to capture prey Colonial Cnidarians - Siphonophores??? Protostomes - Lophotrochozoans - Have trochophore larva  - Some also have lophophore feeding structure - Ecdysozoans - External cuticle that is shed to grow → ecdysis Lophotrochozoans- Phylums Platyhelminthes - Acoelomates - no cavity between body walls and gut - No circulatory systems - Lophotrochozoans- Phylum Mollusca - Body organised into food, mantle, and viscera - Unsegmented Lophotrochozoans- Phylum Annelida - Metamerism - Well-defined segments Ecdysozoans - Growth in through ecdysis of the cuticle - Acellular - secreted by epidermal cells Ecdysozoans- Phylum Nematoda - Pseudocoelomate - body wall lined with mesoderm, gut has no mesoderm envelope - Unsegmented Ecdysozoans- Phylum Arthropoda - Jointed chitinous exoskeleton - Segmented body (has body parts) - Jointed limbs - Tagmatization → fusion of body segments Deuterostomes- Phylum Echinodermata - Bilaterally symmetrical larvae - Pentaradiate symmetry as adults - Water vascular system and tube feets Deuterostomes- Phylum Hemichordata - Pharyngeal gill slits - Dorsal nerve cords stomochord →notochord (rod-like) Deuterostomes- Phylum Chordata - Notochord - Dorsal hollow - Nerves cord - Perforated - Pharynx (gill slits) - Segmented muscles with post-anal tail Theme 3- plants Cannabinoids accumate in flower buds → genes expressed from cannabinoid during flwoering stage When did plants and animals diverge? → Endosymbiotic events If plastid was introduced first → no motility, no aerobic respiration, and will only have photoautotrophic behaviours Q. Are plants sessile or immobile? - Very slow mobility Q. Is immobility a luxury or a disadvantage? - Disadvantage as movement is the growth and climate/condition changes quickly - Needs to be able to move Characteristics of Land Plants - Eukaryotes - Almost all are photoautotrophs but not always - Multicellular - Sessile or stationary ( b/c its photosynthetic + rooted) - Cell walls - Alternation of generations life cycle - Embryo (sporophyte) retained on the gametophyte tissues Monotropa uniflora is a heterotrophic plant that lacks chlorophyll - Cannot produce their own food - Even with no chlorophyll, plants in dark area can grow by absorbing nutrients from other plants MIDTERM Q, - Not all plants are photoautotrophs - Fungi doesn't have flowers so we know they are plants Plant Cells features: - Has primary cell wall surrounding the plasma membrane abd cell contents - Has cellulose fibres (comes from 1st+2ndary wall) - Rigid but flexible - Also has secondary cell wall that gives the plants rigid (only some plants though) Cellulose = polymers of glucose and unbranched - Most abundant organic polymers - Roughage or fibre in humans - Cotton is almost + pure cellulose Secondary cell wall → some plants have it - Xylem, sclerenchyma - Cellulose fibre anchored with lignin - Lignin present in secondary cell wall → hydrophobic leads to more rigid - Stringer and more rigid - Creates waterproof barrier *Turgor pressure provides rigidity by pushing against cell wall Less tonicity → higher h20 outside = hypotonic → less solute than the cell to cell becomes turgid due to pressure - Plants cell gain or lose water than osmosis - Walls has tensile strength but the rigidity comes from turgor - Vacuole has higher solute concentration and osmosis flow of water occurs from outside cell (lower solute) into the vacuole - Vacuole → membrane-bound organelle in plants for water balance Hypotonic → turgid because water goes into the vacuole therefore puts pressure in the cell walls Hypertonic → the water goes outside therefore vacuole shrinks How is the plant cycle different from the cycle of animals? - One free living diploid individual - Gametes (haploid ) are formed through meiosis - Gametes are not free living Alternation of generations Sporophytes (2n) → produces spore (n) through meiosis - Spores are haploid, unicellular and makes gametophyte (n) through mitosis Gametophytes(n) → multicellular and makes unicellular gametes Embryo → 2n, multicellular *After fertilisation, embryo is retained in female gametophyte tissue Land plant Classification 1. Vaculature (Vascular bundles) a. Consists of xylem, phloem, parenchyma cells and fibre cell i. Fibre cell are sclerenchyma cells that provide rigid to support the xylem and phloem ii. Xylem are water conducting cells → dead at maturity iii. Phloem cells transport sugar → alive cells b. The circulatory system that compliments plants water + nutrients c. Dynamic reaction to soil environment helps maintain turgid state Xylem + Phloem - Water conducting ells are strengthened by lignin  - Lignin is the second most abundant polymer after cellulose - They are hydrophobic and aromatic - Allows plants to increase rigidity → height of plants 2. Seeds - Cotyledon - Acquires stem cell zone radical → undifferentiated cell - Seeds ferns → first to evolve seeds - Higher diversity = greater ability to progate/ reproduces Non-vascular plants: - First to evolve - Lacks vascular tissue - Haploid gen is dominant - Less rigidity = haploid lifetime - Diploid, smaller/shorter time - Ex → Bryophytes Vascular seedless plants: - Has vascular tissue but has no seed - Diploid gen is dominant - Ex→ Lycophytes Vascular seed plants: - Has vascular tissues and has seeds - Last evolved - Diploid dominance - Ligdon fibres increases development - Ex. → Gymnosperm 1. Non-Vascular Plants → Bryophytes - First to appear - Lacks conducting tissue → no secondary cell wall - Grow close to ground on wet site - Provide ecosystem service - Reduces bankside corrosion - Water retention - Insulation - Biofuel - Medicine - Bryophytes are Poikilohydric - Lacks ability to control water - If habitat dries out, they also dries out - Are drought tolerators Tolerators : osmotic adjustments, cell wall elasticity Avoiders : stomatal conductance, leaf orientation + area Life Cycle of a Moss * Algae moves to land and becomes moss? - Spread out from water to rocks - Need to develop support + structure - No rigidity needed in water - Can't grow upwards Gametangia → produces gametes in shelter - Archegonia : egg produces gametophyte - Antheridia: sperm producing gametophyte - Filamentous Protonema → spores that germinate Bryophyte life cycle : - Needs water to run the cycle - Gametophyte is dominant phase - Flagellated sperm swims to the egg so dependent on water  - Sporophyte/ sporangium produces haploid spores *disadvantage is that they require water in every stage 2. Seedless Vascular Plants → Lycophytes and Pterophytes - Flourish in moist environment - Dominant phase is sporophytes - Spores protected with resistance coat - Pollen tube evolved to carry sperms - No flagella in sperm - embryo/seeds protected In Lycophyte only: - Modification of stems - Narrow leaves with one strand of vein/ vasculature - They all have Microphylls (early leaves) Apical dominance : - Broader leaves with multiple veins - Increases in SA for absorbing - Has UV radiation → photosynthesis → cooling the plant by transpiration Pterophyta (ferns ) - Ferns are most abundant group - Plant body is sporophyte stage - Wet to arid habitats - Has divided leaves → fronds - Has roots and vasculature Midterm Q : How does antheridiogen work? - Released by archegonia - Stops growth of female tissue in surrounding organism if female part develops first - Increases chance of cross-fertilization 3. Seed plants - Has seeds and vascular tissue - Gymnosperm (naked seeds) - Dominate the land terrains - Dominant phase is sporophytes - Flowering plants (seeds are covered) Gymnosperm (naked seeds) - Naked seed plants - Pollen grains produce non-motile sperm - Pollination: transferring pollen to female, no water needed - Pollen (male gametophyte ) is released  - Fertilisation makes zygote/embryo which allows to desicate and be dispersed Megaspore = female cones Microspores = male cones Inside the ovule → megasporangium → megaspore produces female gametophyte → archegonia → egg cell - The female gametophytes is protected by layers of tissue Q. How do male sperm find egg? - Mature pollen are winged and transfers to ovule - Pollen is dry so it hydrates on female tissue to make the pollen tube - Polarized growth = one direction - Angiosperm = fast pollination Seeds: - Dormancy is important to protect the embryo until conducive condition Phylum Coniferophyta - Conifers which are the most common gymnosperm - Pines, firs Angiosperm, : Flowering plants - Largest group of land plants - Makes flower and seeds - Forms ovary → becomes the fruit - Ovule becomes seed - Divided into : - monocots : one seeds leave - Single cotyledon - Has parallel leaves - Has 3 petals - eudicots : 2 seed leaves - 2 cotyledons - Has lots of branching - Has 4 or more petals - Goes through Double fertilisation - 1st = one sperm cell from pollen fertilizes the egg cell forming a zygote - 2nd = another sperm fertilizes two nuclei in ovule central cell → forms triploid cell (happens in endosperm) Angiosperm Reproduction video: 1. Megaspore formation in ovary →turn into female gametophyte ovary has ovules - ovules have megasporophyll [mother cell] which goes through meiosis to make 4 megaspore - three megaspores degenerate - only one functional megaspore. this goes to 3 mitotic division = 8 cells into embryo sacs  - Embryo sacs: 3 antipodal cells (at top) - 2 synergids (help guide pollen] - 1 egg cell [to be fertilised] - 2 nucleic [ at centre] 2. Pollination = transfer of pollen - pollen germinates and pollen tube grows down →females give hydration - Cytoplasmic streaming helps nutrients and signals move towards the ovule. - The pollen tube releases two sperm cells. [double fertigation] - seed hypocotyl = root stem - Cotyledons = seed leaves - Radicle = primary root - seed swells to a fruit 3 mitotic division in megaspore = 8 cells ex. 60 ovules = 60 fertigation can happen Q. How does the pollen tube know where to go? - It follows a chemical gradient Endosperm : maternal (2n) - One sperm fuses with two Paternal (2n) - Sperm cell that fuses with haploid (n) 2 from mother + 1 from father How plants perceive and respond to light → seeds germinate more with red light chamber (600) and less with far-red chamber Midterm Q: Inactive form : Pr → after gets hit with red light, it becomes active → Pfr → more far-red means more Pr therefore inactive - Seeds germinate when receiving sufficient red light Pollinators undergo coevolution with angiosperms - Coevolution occurs when 2 or more species interact closely in same ecological setting Tropics have high energy and biodiversity - More energy more productivity Arctic - Has little life and few animals Q. Comparing terrestrial to aquatic animals / plants - Aquatic plants lack support structures → large fishes lack bones Theme 3 - plants - Origin of Earth = 4.6 Ga - Origin of life is approx 3.7-4 Ga - True colonisation began with fungi, early embryophytes and then animals Colonisation of land : life on land was only at last 500 million years Challenges: 1. Desiccation → protection from drying out ( a coat or skin to prevent body fluids from evaporation) 2. Respiration → in water, there's dissolved oxygen and carbon which are exchanged so organisms needed to invent new structures to breathe 3. Reproduction → In water, eggs and sperms are released into the water. Land organisms have to evolve to become good reproducers under the desiccating conditions. 4. Locomotion → needs new features for animals and to defy gravity in plants 5. Senses: organism on land had to adapt to the changes of light, sounds and smell Algal mats were first to come out and live on water edges The first true fully terrestrial organisms were non-vascular plants The first terrestrial animal was Arthropods Q. Why is inhabitation of land by plants important? - Oxygen, drugs, food, fibre, timber, and ecosystem services Q. How did early land plants survive? - Desiccation - Growth erect - Apparatus to respire Major Adaptations to dry conditions on land 1. Waxy cuticles a. Helps prevent them from drying out (water loss prevention) b. Has layers such as epidermal layer → outer cell c. The wax has fatty acids 2. Stomata a. Pores that allow exchange of gasses across leaf surface b. Opening and closing of pores controlled by specialized cells called guard cells i. Guard cells help with turgor pressure  ii. Opening and closing depends on water or sunlight 1. Closed if no water in soil c. Found in earliest branches of land plants → non-vascular plants 3. Vascular tissue a. Cell walls that thickened with rings of lignin b. Vertical growth i. Helps transport water by the elongated conducting cells ii. Maintain rigid polymer ring around it c. Has Xylem i. Dies at maturity d. Has tracheids = ferns and gymnosperm has i. Opening in secondary wall e. Vessels = useful for angiosperms i. Shorter but wider than tracheids 4. Root system a. Non-vascular plants (mosses)--> has rhizoids b. What stage will u see rhizord in vascular plants?--> fern gametophytes * Stomata was already in mosses (non-v) * vascular tissues with lignified cells and leaves evolved in lycophyte * non-swimming sperm and seeds evolved in gymnosperms *Flowers and ovaries evolve in angiosperms 1. Evolutionary timeline Algae > mosses > ferns >conifer(gymno) 2. Water availability Algae > mosses > ferns >conifer(gymno) (high) (low) 3. Free living zygote Only in algae 4. Length of gametophyte (n) generation Algae > mosses > ferns >conifer(gymno) (long) (short) 5. Length of sporophytes (2n) generation Algae < mosses < ferns < conifer(gymno) 6. Relative size of gametophyte (n) Algae > mosses > ferns >conifer(gymno) 7. Relative size of sporophyte (2n) Algae < mosses < ferns < conifer(gymno) 8. Protection of zygote/embryo (2n) Algae > mosses > ferns >conifer(gymno)