transcription
the synthesis of RNA from a DNA template
translation
specialized molecular structures within the cell read the RNA molecule to determine what building blocks to use to create a protein.
converts information stored in the language of nucleic acids to information in the language of proteins.
Hardy Weinberg Equilibrium
1. There can be no differences in the survival and reproductive success of individuals
2. Populations must not be added to or subtracted from by migration
3. There can be no mutation
4. The population must be sufficiently large to prevent sampling errors
Modern Synthesis
the marriage between Mendelian Genetics and Darwinian evolution.
Ronald Fischer realized that instead of a single gene contributing to a trait like human height, there could deb several genes that contribute to the trait.
End-Cretaceous extinction
65 mya
the mass extinction eliminated dinosaurs (except birds) and made way for the age of mammals
caused by impact of a giant meteorite
End-Permian Extinction
occurred 252 million years ago at the end of the Permian period
most devastating mass extinction to date
>90% of all genera recorded in late Permian oceans disappeared, especially animals like corals and sponges with heavy skeletons
may have occurred due
Oxygen
levels increased to levels humans could breathe about 580 mya.
coincided with first appearance of animals in fossil record
oxygen rose to 1%-10% of modern levels about 2.4 by a
anthropogenic CO2 sources
fossil fuel burning (80%)
deforestation
where does anthropogenic CO2 go?
ocean
land
atmospheric CO2.
- about 50% of the CO2 generated by human activities ends up in the atmosphere.
Glacial periods
glacial advances: the circulation of carbon rich deep ocean waters back to the surface slows, causing more inorganic carbon to accumulate in the deep sea
glacial retreat: the oceans circulate more vigorously, returning CO2 to the surface and then to the a
Conjugation
DNA (usually a plasmid) from a donor cell is transferred into the recipient cell
Transformation
DNA released into the environment by dead cells is taken up by a recipient cell
Transduction
DNA is transferred from a donor to a recipient cell by a virus
Fermentation
an anaerobic process that converts sugars to acids, gasses, or alcohols
Microbial mats
bacteria and archaea form communities
have vertical gradients of abiotic factors
-top surface dominated by cyanobacteria
-anoxygenic photosynthetic bacteria absorb sunlight using bacteriochlorophyll, a light-harvesting pigment closely related to chlorophy
Nitrogen Fixation
N2---> ammonium (NH4+)
by symbiotic heterotrophic bacteria in root nodules of plants
by cyanobacteria, heterotrophic bacteria, and archaea in microbial mats
many archaea are extremeophiles
Thermophilic: heat loving
Hyperthermophilic: very heat loving (up to 122 degrees C)
Halophilic: salt-loving
Acidophilic: acid-loving
Stromatolites
history of microbial communities
early record of life on earth
Bacteria
tiny
no nuclear membrane
cell walls made of peptidoglycan
genes arrayed along a single circular chromosome
lack membrane bound organelles
archaea
genes arrayed along a single circular chromosome
no membrane bound nucleus
no peptidoglycan, cellulose, or chitin
membranes are made of lipids different from the fatty acids found in bacterial and eukaryotic membranes
Cyanobacteria
all bacteria capable of oxygenic photosynthesis
Purple bacteria
capable of photoautotrophic growth using bacteriochlorophyll and a single photosystem
most show evidence of metabolic diversity and can grow heterotrophically in the absence of light or appropriate electron donors
Green sulfur bacteria
commonly gain electrons from hydrogen sulfide and deposit elemental sulfur on their walls.
unlike most groups of photosynthetic bacteria, green sulfur bacteria are highly intolerant of oxygen gas.
3 major divisions of archaea
1. Crenarchaeota
- include acid-loving organisms
- include hyperthermophiles
2. Eukarchaoeta
- include acid-loving organisms
- include hyperthermophiles
- include heat loving methane-producing and salt-loving microorganisms
3. Thaumarchaoeta
- most abunda