Genome Variation Flashcards
Neutral mutation
Neutral mutations do not affect the organisms functions
or ability to generate offspring
Deleterious mutation
Deleterious mutations disrupt some functions
Advantageous mutation
Advantageous mutations enhance some function
Somatic mutation
Somatic mutations occur in nongermline tissues, and thus cannot be inherited.
Germline mutation
Germline mutations are present in egg or sperm and can be inherited.
Mutation rate
Rate at which new mutations arise
Substitution rate
rate at which new mutations become fixed in a
species. Depends on mutation rate and election.
Transition
Mutation within nucleotide groups: purines (A,G) or pyrimidines (T,C).
Transversion
Mutation between nucleotide groups: purines (A,G) or pyrimidines (T,C)
Polymorphism
occurrence of two or more distinct genetic
variants at one genomic position (locus).
SNP
Single nucleotide polymorphism
What makes mitochondrial DNA useful for studying human evolution?
Mitochondrial DNA
(mtDNA) is inherited only
from the mother.
The mutation rate is 10
times higher than for
nuclear DNA.
mtDNA is easy to isolate and sequence, even from old tissue.
Genetic distance
The number of substitutions that have
accumulated between two homologous sequences after
they diverged from a common ancestor.
p-distance
Proportion of sites that are different
between the two sequences
Why is p-distance underestimating genetic distance?
Mutations can also convert a nucleotide back to the original.
Multiple mutations may occur at the same position.
