Midterm 3 Flashcards
When was the end-Permian mass extinction?
251 mya
When was the end-Cretaceous mass extinction?
65 mya
What are adaptive radiations?
Rapid increases in species diversity that are driven by adaptation to diverse environments.
They happen when there is little competition between organisms.
Complex traits evolve ________.
incrementally/slowly over time
To contain life, what 4 things likely happened?
1) abiotic (non-life) synthesis of organic compounds
2) abiotic synthesis of macromolecules
3) formation of “protocells”
4) formation of self-replicating, information-
containing, catalytic molecules (e.g., RNA)
What are fossil stromatolites?
Structures formed by films of prokaryotes (especially a kind of prokaryote called “cyanobacteria”). A film grows, then another grows on top, etc… and eventually a large, layered structure forms.
What was the oxygen revolution?
Rapid increase in oxygen levels at 2.4 bya
What is evolutionary radiation?
When many species are formed in relatively short amounts of time
What are the 3 basic shapes of prokaryotes?
spherical (cocci)
rod-shaped (bacilli)
spiral
____________is a key component of the cell wall in bacteria
peptidoglycan
What color is gram positive bacteria?
What color is gram negative bacteria?
gram positive - blue
gram negative - red
What is the difference in structure between gram negative and gram positive bacteria?
Gram-negative has two membranes
What are fimbriae?
Short hair-like structures that prokaryotes use to attach to substrates or to each other
What are pili?
Long hair-like structures that prokaryotes use to attach to each other for the purpose of transferring DNA between cells
The prokaryotic genome consists of what two things?
- Circular chromosomes
- Plasmids
What are the 4 nutritional modes of bacteria?
photoautotrophs - light and CO2
photoheterotrophs - light and organic carbon source
chemoautotrophs - chemicals and CO2
chemoheterotrophs - chemicals and organic carbon source (all animals)
Define facultative anaerobe
Can alternate between aerobic and anaerobic metabolism, depending on whether or not oxygen is present
What are the 3 ways prokaryotes use nitrogen?
Nitrogen fixers – convert atmospheric N2 gas into ammonia (NH3), which is usable by other organisms (used to make proteins and nucleic acids)
Nitrifiers – oxidize NH3 to nitrite (NO2) or nitrate (NO3)
Denitrifiers – use nitrite or nitrate as terminal electron acceptors during anaerobic respiration, producing N2 gas
Name 3 ways prokaryotes get DNA
Transformation – picking up DNA from the environment
Transduction – getting DNA injected by a virus
Conjugation – getting DNA from another bacterium. The cells connect via a pilus, and DNA (either plasmid or chromosome DNA) is transferred from one to the other.
The movement of DNA between individuals of different species, or ______________________ is very common in prokaryotes.
horizontal gene transfer
In prokaryotes, we usually focus on genes coding for ________.
ribosomal RNA (rRNA)
From these which are gram negative:
proteobacteria
spirochetes
chlamydias
cyanobacteria (photoautotrophs with chlorophyll a)
High GC gram positives
Low GC gram positives
All except the gram positives
Eukaryote chloroplasts are derived by _________ from
____________.
endosymbiosis , cyanobacteria




























