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8 Cards in this Set

  • Front
  • Back
RNA editing
mRNA cytosines are converted into uracils after transcription. Observed in plant mitochondria.
Gene conversion
Genes are mutated to resemble other genes. Caused by mismatch repair mechanism acting on heteroduplex DNA.
Unequal cross over
Sequence regions from two separate chromosomes with significant sequence similarity may form cross overs during meiosis. Exchange of the amount chromatid maybe unequal.
Causes duplications and deletions.
Codon usage bias
Some codons are more abundant in a genome than what would be expected by chance. Species specific property. Due to overexpression of certain tRNAs.
Purifying selection
Selection pressure that disfavours codons whose cognate tRNAs are rare. Stronger for highly expressed genes.
Biased mutation pressure
Preference of silent codon positions to mutate to either AT or CG. Probably due to the habitat temperature, for example thermophiles probably have mutation pressure towards CG. Also, caused by ueven tRNA abundance, for example in Drosophila
A genomic segement with uniform GC / AT composition. Present in eukaryotic genomes.
Relative synonymus codon usage
A statistical measure of codon usage bias. For a given codon:
RSCU = Xi / X