Bio 94 Burley Chpaters 32 and 33
Bio 94 Burley Chpaters 32 and 33 05220
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This 3 page Class Notes was uploaded by Karina Martin on Tuesday February 16, 2016. The Class Notes belongs to 05220 at a university taught by Nancy Burley in Winter 2016. Since its upload, it has received 27 views.
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Date Created: 02/16/16
Bio 94 Burley Chapter 32: Fungi 1) Intro to Fungi a) Poor fossil record b) Came about ~ 1.5 billion years ago (bya) according to molecular evidence i) Oldest fossils ~ 650 my c) There are 80,000 species that have been described 2) Traits/Characteristics a) unicellular (“yeast”) or multicellular (mycelium composed of hyphae) b) Heterotrophic Extracellular digestion c) Cell walls – similar to plants but made of chitin (animals) d) Store food as glycogen (animals), not starch (plants) e) Have (Chytrid) flagellum like animals f) Clade = Opisthokonta g) Hyphae = thin, branching filaments, divided by septa; pores allow flow of cytoplasm between cells i) Hyphae grow towards food; die back ii) High surfaceto –volume ratio 3) Lifestyles a) Decomposers (saprophytes) i) Organisms that absorb dead plants ii) Digest lignin and cellulose iii) Cycle carbon into sugars (glucose) iv) Cycle N and minerals b) Parasites/predators i) To plants ii) To animals iii) Frequency dependent selection iv) To protists v) Other fungi c) There are lots of fungi that can kill animals i) Most fungi types specialize/focus on one species d) Mutualists i) mycorrhizae – association between fungi and living roots of most (> 90%) vascular plants; 4) Types a) Ectomycorrhizae i) hyphae surround plant cells – (Nitrogen, some Phosphorous) b) Endomycorrhizae (Arbuscular) i) hyphae penetrate plant cells – (mostly Phosphorous) 5) Uses a) baking b) brewing c) antibiotics, drugs, steroids, etc. (penicillium, the Pill) d) commercial acids (citric acid in Coke – Aspegillus) e) stinky cheeses (blue, Camembert) f) cheese substitutes, popcorn topping, mycroprotein (Ascomycotes) g) microremediation Bio 94 Burley Chapter 33: Origin of Metazoans 1) Metazoans a) Multicellular animals i) 1.3+ million species 2) Traits of Metazoans a) chemoorganoheterotrophs b) lack cell walls (instead have structural proteins) c) development: cleavage and gastrulation d) Diploid phase dominates life cycle e) Sexual reproduction f) Nerves and muscles 3) Origins of Metazoans a) Monophyletic b) Ancestor = colonial protest similar to extant choanoflagellates 4) When did they evolve? a) Best estimate of origin of kingdom Animalia: i) 535 – widely accepted fossils ii) 750 mya (recently discovered tiny fossils) iii) Approx. 1 bya (molecular evidence) b) How does molecular evidence give us a different estimate? i) Molecular clock (1) hypothesis that amino acid base substitutions accumulate as a linear function of time. (2) Method to estimate divergence dates of lineages (when one lineage splits into 2) (a) Valid when: # of nucleotide substitutions is a linear function of time (b) Useful: when common ancestor of taxa of interest is not known (c) Reliability: when multiple clocks give similar dates (3) Molecular clock evidence indicates animal lineage originated 1+ bya ii) Mutations are random – but over long spans – may occur at “constant” rate 5) Cambrian Explosion a) What happened? i) The simultaneous appearance of metazoan phyla in fossil record and rapid diversification (starting ~543 mya) ii) Larger, more complex, FOSSILIZABLE animals suddenly appeared (tougher exterior, harder parts) b) Contributors i) Increase in free oxygen (cynobacteria, 2.5 bya; eukaryotic algae, 1.8+ bya) ii) Colonization of new biotic niches (1) As some organism got larger, new biotic niches were created (2) Example: Parasites: 7 spp mites on 1 sp parrot iii) Intensification of coevolutionary “arms races” among animals (1) previously only softbodied animals, probably not active hunters iv) Proliferation of hox genes (1) Specify axis and segment identity (location) within embryo to develop certain structure v) Interacting factors extensive positive feedback vi) Process whose result is reinforcing, accelerating the process.
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