Week 5 Notes- Chapters 26 and 27
Week 5 Notes- Chapters 26 and 27 BIOL 102 001
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This 5 page Class Notes was uploaded by Kaeli on Monday September 19, 2016. The Class Notes belongs to BIOL 102 001 at University of South Carolina taught by Mihaly Czako in Fall 2016. Since its upload, it has received 5 views.
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Date Created: 09/19/16
Chapter 26 Notes Phylogeny is not a form of classification o The evolutionary history of an organism o Shared ancestor indicates homology Genetic similarity Phenotypic similarities o Need to differ between analogy and homology Analogy is from convergent evolution Structures called homoplaises if analogous Can be determined by computer analysis of DNA Shows same sequences When coincidental, they’re analogous o Groups Paraphyletic groups Clade and one from a close decent Polyphyletic group Group plus one current species from a distant ancestor without the ancestor that connects them Closer to convergent evolution Cladistics group by common decent Clade group including a species and all of its decedents o Also called a monophyletic group o Shared characters Shared ancestral originated from ancestor Shared derived clade specific trait o Tree terms Branch point where lineages diverge Smallest group to the far right of the tree is a taxon Polytomy More than two organisms with a common ancestor Sister taxa 2 organisms with a same common ancestor o Trees do not: Show phenotypic similarities Show when a species evolved Show how much change occurred o Trees do: Show genetic similarity o Why its important Helps to understand biodiversity Genetic history & Change o Histroy DNA that codes for rRNA mutates slowly and helps to find branching points from long ago mtDNA evolves rapidly and is used to explore recent evolutionary divergence o Molecular clocks help make assumptions about molecular change Know that DNA replication misses 1 in a million pairs Use constant rates of evolution help estimate time of change Example: Used to find the origins of HIV in humans Taxonomy is the process of classifying o Systematics classifies organisms based on evolutionary relationships o At first, everything was either plant or animal o Later was five: Monera, Protista, Plantae, Fungi, Animalia Subgroups of Bacteria, Archaea, and Eukarya o Suggests that Archaea and Eukarya are more closely related than to bacteria o Reproduction leads to horizontal gene transfer (if normal) o Chapter 26 Notes Prokaryotes o Structure No nuclear membrane Most are very small Very populous Common shapes spheres rods and spirals Surface structures that stick Exhibit taxis Move relative to a stimulus Flagella are a common structure o Not analogous o Made of different compounds o Divided into Bacteria and Archaea Unicellular o Likely first life o Can create endospores Survive harsh conditions for centuries o Have circular, simpler DNA A single circular chromosome Nucleoid region Smaller rings called plasmids (Bacteria) o Reproduction Binary fission 1 minute 3 hours Not sexual, no recombination in a meiotic sense Genetic diversity Rapid reproduction Mutation Genetic recombination o DNA moves between two cells via transformation, transduction, and conjugation o Transformation: uptake of DNA from environment o Transduction: movement of genes by bacteriophages (viruses) o Conjugation: Similar to sexual reproduction, one cell attaches to another by a pilus, pulls it closer and transfers DNA The presence of a pilus requires a gene for it Called F factor or F plasmid Occasionally part of the chromosome R plasmids carry antibiotic resistance o Metabolic diversity Photoautotrophs Make ATP from light Chemoautotrophs Extract energy from harsh chemicals Photoheterotrophy Light and others Chemoheterotrophy Chemicals and others Oxygen Obligate aerobes o Require O2 Obligate anaerobes o Poisoned by oxygen o Use fermentation Facultative anaerobes o With or without O2 Nitrogen Fixation N2> NH3 (ammonia) o Prokaryotic diversity Some plants have an organ specifically for nitrogen fixing prokaryotes Keep oxygen out Rhizobium Handful of soil may contain 10,000 species of prokaryotes Horizontal gene transfer obscures root of tree of life Agrobacterium produces tumors in plants and is used in genetic engineering Transfers genes into plants o Interdomain transfer o Without prokaryotes, prospects for any other life would be dim. Chemical recycling Symbiotic relationships Bacteria only o Have cell wall (ONLY Bacteria) Made of peptidoglycan (vs cellulose or chitin) Grampositive bacteria have simpler walls with a large amount of peptidoglycan Gramnegative have less peptidoglycan and an outer membrane that can be negative (added lipopolysaccharide) More likely to be antibiotic resistant A protein layer called a capsule covers many prokaryotes o Some have folds in membrane that serve a function Still NOT organelles Archaea o Similar to both Eukarya and Bacteria Closer to Eukarya More shared characteristics o Severe conditions Methanogens Produce methane Poisoned by O2 Halophiles High salt content Thermophiles High temperature