BIO lab test 1 notes.docx

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University of Toronto Mississauga
Christoph Richter

Week 2 : Prokaryotes and protists Prokaryotes - Microscopic, single-celled organisms - Differ from eukaryotes cause they don’t have membrane-bound nucleus - Reproduce asexually through binary fission - Instead of chromosomal dna , their dna store in plasmid (circular loop) - Cells very small (1-2 um and 10 um long) - 2 major domains : archaea, eubacteria Domain Archaea: - Live in extreme anaerobic environments and called “extromophiles” - Classified as thermophiles (high temp), Halophiles (high salty condiotions),acidophiles (acidic cond), methanogens (methane producers) Domain Eubacteria: - Most abundant forms of life - Serve as decomposers, agents of fermentation, nutrient recyclers, aid in digestion - Quiet small and simple shape except for cynobacteria which is more complex Bacteria morpohology - 1 way of identification: shape: rod-shaped cells = bacilli, sperical shaped = -cocci, spiral shaped = -spirilli - Genus species name may reflect nature of groupings : diplo- (cells occur in pairs), strepto- (form chains), staphylo- (form bunches like grapes) ex. Diplococci (sperical bacterium which occurs in pairs) Gram staining - All bacteria classified using gram staining, often first step in identifying unknown bac and also determining resistance to antibiotics - Bac that retain purple colour are gram-positive - Pink colour retain are gram negative - Colours related to composition of outer cells wall of 2 bac : gram+ bac have think outer layer of peptidoglycan that absorbs gram stain, gram – coated with thick lipid bilayer which is selectively permeable to gram stain - Gram + bac more susceptible to antibiotics than gram- , cause substance is easier to pass through their pepto layer - Streptococcos = gram + bac, responsible for causing strep throat Cynobacteria - Often called blue-green algae - Not true algae, they are photoautotrophs (use solar energy to produce food) - Found in fresh and salt water - Anabaena : freshwater, filamentous cynobac , nitrogen fixation produces neurotoxin not toxic to humans but may be to fish, affects water quality (causes bad smell) Protists - Eukaryotic organisms have extensive fossil reccords - Can be autrotrophs, heterotrophs, decomposers - Do not represent monophyletic group - All eukaryotics that are not animals, plants or fungi are protists The “plant-like” protists - Commonly reffered to as algae - Most are phototrophs , use chlorophyll a and membrane bound plasmids to convert solar E to sugar - Volvox – haplion (n) green algo found in freshwater ponds each colony made of 500-600 cells, each cell has pair flagella that beat in unison to propel colony through water colony has anterior and posterior, cells in anterior have enlarged eyespots to orient towards light may produce sexually via cells that divide mitotically to produce sperm packets that travel to other colonies and fertilize cells asexually , cells undergo repeated mitosis and produce smaller spheres, ‘daughter colonies’, when parent colony die, daughters take over or “vegetative cells” - Diatoms – play major role in global photosynthesis and carbon cycle in ocean are dipliod (2n), unicellular, silica-based cell walls “frustules” that fit together like halves reproduction usually asexually, daughter cells receive only ½ of parent cell wall, can eventually reduce the size so small they have to produce sexually - Euglena – unicellular alga freshwater unusual cause it can undergo photosynthesis and also act as heterotroph cell lined with “Pellicle” (non-rigid cell wall) equipped with darkspot for light detection The “animal-like” protists - Found in freshwater and marine env - Many parasitic forms exists - Free-living forms are heterotrophs use engulfing methods to feed - Abmoeba proteus – single-celled protist, moves by “cell-crawling” using extensions of cyctoplasm “pseudopodia” , food is engulfed and stored in ‘food vacuoles’ and ‘contractile vacoules’ used to expel excess water - Paramecium - lined by cilia used to propel through water, posses 2 nuclei – macronucleus and micronucleus undergo asex by fission but also exchange genetic material with opposite mating type by “conjugation” not true sexual reproduction cause no new individuals produced this way feeds through sweeping food particles into “oral groove” lined by cilia - Trypanosoma – unicellular, parasitc, single anterior (front) flagellum partially attached along length of body impact on human health: cause sleeping sickness, chagas disease, has glyoprotein coat so difficult for vaccine against disease - Plasmodium – unicellular, parastic, complex lifecycle split between an insect vector (mosquito) and vertebrate host (humans) , causes malaria The “fungi-like” protists - Often refered to as ‘slime molds’ - Not true fungi - Molds exists as solitary amoeboid that eat soil bacteria, when food scarce, starve and stop dividing which activates AMP signal Week 3 : Primitive land plants - Alternation of generations Nonvascular plants - Evolved from freshwater green algae - Earliest plants : multicellular, lacked vascular tissue (xylem and phloem) - Cause of lack of tissue tend to be struturally simple, small, low to ground, inhabit moist habitats - 3 types : Hepticophyta (liverworts), Bryophyta (mosses), Anthocerophyta (hornworts) - Covered with waxy cuticle to prevent water loss, have pores for gas exchange - Liverworts and mosses have guard cells that open and close pores, pores with guard cells have stomata (but liverworts don’t have stomata) - Presence of rhizoids (short thread of cells for a
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