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
What are three main differences between Archaea and Bacteria?
Archaea:
- DO NOT have peptidoglycan wall
- Have some branched hydrocarbons cell wall
- Grown NOT inhibited by antibiotics
What are some of the extreme environments Archaea can live in?
Thermophilic - very hot
Acidophilic - Low pH
Methanogens - obligate anaerobes
Halophiles - very salty
What are the 3 types of symbiosis?
commensalism: one species benefits, one species is neither
helped nor harmed
mutualism: both species benefit
parasitism: one species benefits, one species is harmed
(when these cause disease, they are called
pathogens)
What are the 2 main components of a virus?
- Capsid - shell of protein
- Genome - single or double stranded DNA or RNA
Describe the lytic cycle for viruses.
What is different about the lysogenic cycle?
Lytic
- Get inside host cell
- Replicate using host cell’s components
- Cell lysis (bursts)
For the lysogenic cycle, the infected cell replicates many times with the dormant virus
How did eukaryotic cells arise from a prokaryotic ancestor?
- Gain flexible cell surface
- Develop cytoskeleton
- Develop nuclear envelope and ability to endocytose external materials
- Aquire organelles by endosymbiosis
Why do scientists believe mitochondria are phagocytosed proteobacteria (gram-negative)?
Mitochondria have:
- 2 membranes
- Use Binary Fission
- Their DNA is circular
- They make their own ribosomes
At some point, an ancestral eukaryote phagocytosed
photosynthetic _______________
that were not digested.
cyanobacteria
• these continued to divide, and
evolved into chloroplasts
Compare plastids and chloroplasts
Plastids are highly specialized, double membrane-bound organelles found within the cells of all plants and algae. A type of plastid called the chloroplast is the cellular location of the process of photosynthesis.
What is primary endosymbiosis?
The original endosymbiotic event: phagocytosis of a cyanobacterium by a eukaryotic cell which evolved into plastids
Primary endosymbiosis gave rise to the plastids of a large clade of eukaryotes called the ___________.
Archaeplastida
The Archaeplastida clade includes
- chlorophytes & charophytes (aka “green algae”)
- land plants
- red algae (red algal chloroplasts retain some pigments that were
present in the original cyanobacterium)
-glaucophytes
Define Secondary Endosymbiosis
endosymbiosis of an archaeplastid cell (which got its plastid via 1° endosymbiosis) in another eukaryote host.
– this process gave rise to the chloroplasts in most other photosynthetic eukaryotes; 2°endosymbiosis has happened repeatedly. Usually retain multiple membranes
All eukaryotes except for plants, animals, and fungi are called ______
Protists
In terms of nutrition, protists can be
photoautotrophs - (e.g., archaeplastids) - these are often called “algae”
chemoheterotrophs - these are often called “protozoans”
mixotrophs – they can do both photoautotrophy AND chemoheterotrophy
What are the 4 major clades of protists?
Archaeplastida - clear synapomorphy: plastids derived from primary endosymbiosis
Excavata - DNA sequence data, unicellular
“SAR” clade
Unikonta - one flagellum, if flagella are present
What is the Diplontic Life Cycle? (animals)
- Gametes (n) fertilize to make Zygote (2n)
- Zygote (2n) undergoes mitosis - forms multicellular organism (2n)
- Organism (2n) undergoes Meiosis to form gametes (n)
*The only haploid cells are gametes*
What is the Haplontic Life Cycle? (fungi, protists)
- Gametes (n) fertilized to make diploid zigote (2n)
- Diploid zigote (2n) undergoes Meiosis to produce haploid cells (n)
- Haploid cells (n) undergo Mitosis forming a haploid unicellular or multicellular organism (n) and gametes (n)
*The only diploid cells are Zigote*
What is the Alteration of Generations Life Cycle? (plants)
- Gametes (n) fertilized to make diploid zygote (2n)
- Diploid zygote (2n) undergoes mitosis to form a diploid multicellular sporophyte (2n)
- Sporophyte (2n) undergoes Meiosis to produce haploid spores (n)
- Spores (n) undergo Mitosis to form haploid multicellular gametophyte (n)
- Gametophyte (n) undergoes mitosis to produce gametes (n)
All members of the Archaeaplastida clade use ___________ as their main photosynthetic pigment.
chlorophyll a (chl a)
_____________ are sister-taxon to the rest of the Archaeplastida.
Glaucophytes
_________ is a paraphyletic group made up of chlorophytes and charophytes
“Green algae”
– in addition to chl a, these contain
chl b; so do land plants
The 3 main groups in the Excavata clade are
diplomonads- reduced mitochondria called mitosomes (don’t function is respiration)
parabasalids - reduced mitochondria called hydrogenosomes (function in anaerobic respiration)
euglenids