Bio 112 notes

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Archasea Bacteria
Luca
Last Universal Common Ancestor
Lucas Characheristics
deduce form shared characteristics of A + B today:
DNA (cf. RNA) genome
No nuclear membrane or intracellular organelles
Electron Transport Chains
(ETC)- ATP (energy)
Proteins
Same genetic code

Prokaryontes 2.75 bya, are responsible for a dramatic increase in atmospheric O2. Cyanobacteria = photosynthesizing bacteria + related prokaryontes Evidence of O2 increase:
Rust in rock (= Fe oxide) dates to 2.75 bya
Increase in O2 cause FeO precipitation FeO (solid)  rock sediment O2 level generated 2.75 bya only 10% more of current
Major O2 increase came later with plant colonization of land (chapter 25)

Fungal and animals arose from protest ancestors
Animals arose form a choanoflagellate-like protest

Animals and fungi evolved from protest ancestors
Unikonta Supergroup
Unikonta= flagellated protists or ancestors were of this type Evidence that animals arose from choanaflagellate ancestor
DNA sequence is most similar of protist animals
Some animals have choanoglagellate-like cells in their anatomy Eg. Sponges-choanocytes=feeding cells
Also Cnidaria(flat worms) have choanoflagellate-like cells

Animals come from a colonial form (since they are multi-cellular)

Land plants evolved from PROTIST ancestor
Supergroup: Archaeplastida

Closest protist relative to land plants= charophyceans of green algae Land plants evolved from a charophycean-like ancestor
Evidence:
DNA sequence similarity
Morphological & physiological similarities

Only a small fraction of Proks cause disease
Most important role= recycling in the ecosystem
Prokaryotes:
Can fix inorganic materials (eg Co, Fe, S) into forms that other organisms can use Decomposers: breakdown materials and release them into the environment Prokaryotes occupy almost every environment in ecosystem

Because –very adaptable.
This comes from
Can divide rapidly (single-celled, pop size can double in
Haploid therefore any mutations are expressed
Any adaptive mutation can rapidly become a major population characteristic

Part 1: Bacteria
External/general characteristics:
Various shapes (cocus, bacilli, spiral)
Average cell size 1/10 of a eukaryote cell (ie 1-5 mm diameter cf. 10-100 mm diameter)

Flagella activity requires ATP
Taxis= movement of a cell towards something
Chemotaxis= movement toward a chemical source
Thermotaxis= movement to a particular temp
Any movement towards (or away) from a source involves alternating directional movement and tumbling Strategy= Random walk (used by simple animals as well)

B. Intracellular structures
No intra-cellular organelles
But funcions are partitioned to different parts of cel
Ex. Electron transport occurs of specific membranes within a cell

Plasmids: extra circles of DNA
Very small~ 500020,000 base pairs
Often encode contingency functions
Ex. Defense proteins such as antibiotics-used to kill other bacterial species

Bacterial reproduction
Occurs when conditions are favorable
Rapid: some bacterial populations can double in size in < 20 minutes When conditions are unfavorable
Bacteria  spores called ENDOSPORES

Spores are highly resistant and hard to kill
Have autoclave to kill = very high temp + very high pressure (standard procedure in labs and in hospitals)

Sources of genetic variations
In contrast to diploid sexually reproducing organism
Mutations are a major source of variation in bacteria
Why?
Haploid so most mutations  visible phenotype
Reproduce rapidly so even though mutations rate/gene same as other organism total number of mutation high

Bacteria don’t have sex but they can exchange limited genetic material Conjugation
Tube= sex pilus
Often used to transfer plasmids sometime some parts of chromosome Fungal and animals arose from protest ancestors
Animals arose form a choanoflagellate-like protest

Animals and fungi...
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