Early Life and Diversification Flashcards Preview

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Flashcards in Early Life and Diversification Deck (18)
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1
Q

Experiments simulating possible early atmospheres have produced _____ molecules from _____ precursors

A

Organic, inorganic

2
Q

What compounds have been found on meteorites as source material for life?

A

Amino acids, lipids, sugars and nitrogenous bases

3
Q

Organic compounds can spontaneously assemble into _____, membrane-enclosed droplets that have some properties of cells.

A

Protocells

4
Q

What might the first genetic material have been?

A

Short pieces of RNA that are capable of guiding polypeptide synthesis and self-replication

5
Q

When did prokaryotes arise?

A

Earliest fossil evidence is 3.5 billion years ago.

6
Q

When did first known diversity of morphology and habitat in stromatolites occur?

A

2.8 billion years ago

7
Q

What was the role of cyanobacteria in early diversification?

A

Cyanobacteria were a type of early prokaryote that released oxygen as a by-product of photosynthesis, thereby changing the earth’s atmosphere and altering the course of evolution.

8
Q

What are the basic structures of a prokaryote cell?

A

Fimbriae: hairlike appendages that allow adhesion to other cells or the substrate

Capsule: sticky layer of polysaccharide or protein that help with adhesion or evasion of a host’s immune system

No nucleus or other membrane-enclosed organelles

Flagella: structures used by most motile bacteria for propulsion, many species can move toward or away from stimulus

Cell wall: structure differs between gram-positive and gram-negative bacteria

Circular chromosome: often accompanied by smaller rings of DNA called plasmids.

Sex pilus: appendage that facilitates conjugation.

9
Q

Is nutritional diversity greater or lesser than eukaryotes?

A

Greater

10
Q

What are the four modes of nutrition in prokaryotes?

A

Photoautotrophy: produce complex organic compounds such as carbohydrates, fats, and proteins with the absorption of light

Chemoautotrophy: inorganic energy sources such as hydrogen sulfide, elemental sulfur, ferrous iron, molecular hydrogen, and ammonia

Photoheterotrophy: use light for energy, but cannot use carbon dioxide as their sole carbon source. Consequently, they use organic compounds from the environment to satisfy their carbon requirements; these compounds include carbohydrates, fatty acids, and alcohols

Chemoheterotrophy: nutrition comes from inorganic energy sources but an organic substrate is required; specifically one in which simple organic molecules provide a source of carbon for biosynthesis

11
Q

What are the three respiration types?

A

Obligate aerobes: Need o2
Obligate anaerobes: poisoned by o2
Facultative anaerobes: can survive with out without o2

12
Q

What can prokaryotes do with nitrogen that eukaryotes cannot and through what mechanism?

A

Fix it, aka convert atmospheric nitrogen to ammonia through metabolism.

13
Q

Biofilms are an example of what kind of cooperation between what?

A

Metabolic, where metabolic products are exchanged between different species.

14
Q

How do prokaryotes reproduce?

A

Binary fission

15
Q

What factors promote diversity in prokaryotes?

A

Rapid reproduction, mutation and genetic recombination.

16
Q

What mechanisms of recombination can happen between two different cells? How does this lead to adaptive evolution?

A

Transformation, transduction or conjugation.

By transferring advantageous alleles for things like antibiotic resistance.

17
Q

What are the two largest prokaryote groups?

A

Proteobacteria and gram-positive bacteria

18
Q

In what ways are prokaryotes the key to survival of many species?

A

Element cycling: decomposition by heterotrophic prokaryotes, synthetic activities of autotrophs and nitrogen-fixation

Symbiotic relationships with hosts : can be mutualistic, commensalist, or parasitic

Pathogenic endo or exotoxins

Other uses: bioremediation, synthesis of chemicals