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24 Cards in this Set
- Front
- Back
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How old is earth? How old is microbial life?
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4.5 billion years
3.86 billion years |
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What are stromatolites?
What is the difference between modern and ancient Stromatolites? |
Stromatolites are fossilized microbial mats that contain trapped sediment and filamentous prokaryotes
Modern stromatolites: oxygenic phototropic cyanobacteria Ancient stromatolites: anoxygenic filamentous bacteria |
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what is the Surface Origin Hypothesis?
What is wrong with it? |
The first membrane enclosed, self replicating organisms came out of primordial soup (organic and inorganic compounds in ponds)
Dramtic temperature fluctuations and dust from meteors refutes this |
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What is the subsurface origin hypothesis?
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First membrane enclosed self replciating organisms came from hydrothermal springs on ocean floor. Steady environment and supply of nutrients
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What is the RNA World Theory?
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first self-replicating systems were RNA. can bind small molecules, and has catalytic activity: may have catalyzed it's own self-replication. Eventually became DNA (more stable) . Build-up of lipids and phospholipid membrane vesicles.
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What is LUCA
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Last Universla Common Ancestor: group of cells that diverged into ancestors of modern day Bacteria and Archea. Probably anoxic, chemolithotrophic.
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What was the Great oxidation Event?
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2.7 Billion years ago, cyanobacteria developed photosystem that used water instead of H2S. created oxygen as byproduct. Oxygen concentrations were raised, until free oxygen became part of Earth's atmosphere.
Needed to interact with abundant reduced materials in ocean first. |
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What are banded iron formations? how were they formed
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Formed when oxygen from cyanobacteria reacted with dissolved iron in the water. Formed insoluble iron oxides that precipitated out.
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What are some example of genetic changes?
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Mutations, gene duplciation, horizontal gene transfer, gene loss
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What is phylogeny?
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Evolutionary history of a group or organisms. inferred indirectly from nucleotide sequence data.
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What is a widely used phylogenetic marker, and why is it used?
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Small Subunit RNA gene
16S in prokaryotes 18S in Eukaryotes Constant, conserved, sufficient length. |
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What is the procedure for comparative rRNA sequencing?
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Amplification of the gene encoding the rRNA
Sequencing of the amplified gene Analysis of sequence in comparison to other sequences |
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What is Evolutionary Distance?
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Percent of non-identical sequences between the rRNA of two organisms.
Correct Ed: accounts for back mutation. |
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What are the two major groups of Archea
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Crenarcheota
Euryarcheota |
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What are thw three methods of the Polyphasic Approach to taxonomy
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Phenotypic Analysis
Genotypic Analysis phylogenetic analysis |
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What is phenotypic analysis?
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Examines morphological, metabolic, physiological and chemical characteristic of organism
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What are two methods of phenoptyic analysis
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Fatty Acid analysis - looks at variation of the types and proportions of fatty acids present in membrane lipids.
Biolog Profiling - looks at the various chemical reactions an organism can perform, and it's carbon sources |
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What is Genotypic analysis?
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Looks at genome of organism
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What are some methods of Genotypic analysis?
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DNA-DNA hybridization
Multilocus Sequence Typing |
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What is DNA-DNA hybridization?
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DNA of two species are hybridized to see the similarities
useful complement to SSU rRNA sequencing. useful for differentiating very similar organisms 70% or higher- same species 25% or higher - same genus |
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What is Multilocus Sequence Typing?
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Several Housekeeping genes are sequenced
can different very close strains |
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What are some important traits members of the same species must share
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>70% in DNA-DNA hybridization
>97% in 16s rRNA sequencing |
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What is Multigene Sequence Analysis?
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like MLST, but uses whole sequences and comparisons are made using claudistic methods
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What is Whole Genome sequence analysis?
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Genome structure
gene content gene order |
