Early Life and Diversification Flashcards
Experiments simulating possible early atmospheres have produced _____ molecules from _____ precursors
Organic, inorganic
What compounds have been found on meteorites as source material for life?
Amino acids, lipids, sugars and nitrogenous bases
Organic compounds can spontaneously assemble into _____, membrane-enclosed droplets that have some properties of cells.
Protocells
What might the first genetic material have been?
Short pieces of RNA that are capable of guiding polypeptide synthesis and self-replication
When did prokaryotes arise?
Earliest fossil evidence is 3.5 billion years ago.
When did first known diversity of morphology and habitat in stromatolites occur?
2.8 billion years ago
What was the role of cyanobacteria in early diversification?
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.
What are the basic structures of a prokaryote cell?
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.
Is nutritional diversity greater or lesser than eukaryotes?
Greater
What are the four modes of nutrition in prokaryotes?
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
What are the three respiration types?
Obligate aerobes: Need o2
Obligate anaerobes: poisoned by o2
Facultative anaerobes: can survive with out without o2
What can prokaryotes do with nitrogen that eukaryotes cannot and through what mechanism?
Fix it, aka convert atmospheric nitrogen to ammonia through metabolism.
Biofilms are an example of what kind of cooperation between what?
Metabolic, where metabolic products are exchanged between different species.
How do prokaryotes reproduce?
Binary fission
What factors promote diversity in prokaryotes?
Rapid reproduction, mutation and genetic recombination.
