Ch. 6 Genome Evolution, Clusters, and Repeats (Exam 1) Flashcards
Define genome evolution.
Process by which the genome changes in structure or size over time
What key process is responsible for genome evolution?
Mutation
Define silent mutation.
Mutation that does not change the amino acid sequence of the polypeptide product
Define synonymous change.
No change in coding function of the genome
Define nonsynonymous change.
Mutation altering the codon
What is the end result of the nonsynonymous change on the amino acid sequence?
Alteration, either in the form of a missense or nonsense codon
What influences the fate of mutations in subsequent generations?
Selective pressures
How do selective pressures treat positive mutations?
As good changes to be passed on
How do selective pressures treat negative mutations?
As bad changes that need to be eliminated if possible
In what 2 ways can mutations occur in noncoding regions?
1) Altering a regulatory sequence
2) Changing the secondary structure of DNA to affect gene expression
Many changes in noncoding regions might be selectively { } mutations, having no effect on the phenotype of the organism.
Neutral
What are hotspots in terms of mutation?
Areas in the genome where mutations occur much more frequently
Mutations with a low frequency in a population are very likely to be { } from the population by chance.
Lost
What is fixation in terms of mutation?
The spread of through a population and the eventual replacement of the original sequence (i.e. retainment)
Define divergence in terms of nucleotides.
The percentage of positions at which the nucleotides are different
What is a convergent mutation?
The same mutation at the same site in two separate lineages
In what 3 structures does duplication occur (HINT: large, medium, small)?
Genome, chromosomes, and genes
What is the initial result of gene duplication?
2 identical genes
What happens to the first gene copy after the initial duplication?
It will retain the original nucleotide sequence or something similar
What happens to the second gene copy after the initial duplication?
It is not subjected to the same selective pressures as the other, so it could mutate
What do mutations within a gene copy provide?
A new, useful gene function
What is a pseudogene?
An inactive gene homologous to functional gene(s) with no functional role
How does a pseudogene form?
A gene gets inactivated by mutation and then gets more mutations
What are two ways to rearrange existing gene domains to result in novel protein functions?
Domain duplication and shuffling
