Unit 2: Sources of genetic variation Flashcards
Mutation
An inherited change in genetic information
An inherited change in genetic information
Mutation
Mutations are a source of _______ and _______
genetic variation; diseases
How are mutations used to help in understanding basic biological processes? What is this technique called?
Studying mutations that disrupt normal processes often leads to the identification of genes that normally play a role in the process and can help in understanding the molecular details of a process. This technique is called genetic dissection.
Somatic mutations
Mutations which arise in somatic (body) tissues. It’s the basis for cancers.
germ-line mutation
Mutations that arise in cells that ultimately produce gametes
gene mutation
Mutations that arise within a single gene
base substitution
The simplest type of gene mutation that is the alteration of a single nucleotide in DNA
transition
A purine is replaced by another purine. Same for pyrimidines.
transversion
A purine is replaced by a pyrimidine or vice versa.
insertion
The addition of one or more nucleotide pairs
deletion
The removal of one or more nucleotide pairs
frameshift mutation
Changes in the reading frame of a gene
in-frame insertion/deletion
Mutations not affecting the reading frame. Consist of insertions or deletions occurring in multiples of three.
expanding nucleotide repeat
Mutations in which the number of copies of a set of nucleotides increases in number.
forward mutation
A mutation that alters a wild type phenotype
reverse mutation
A change from the mutant phenotype back into the wild type phenotype
missense mutation
A base substitution that results in a different amino acid in the protein
nonsense mutation
A mutation that changes a sense codon (one that specifies an amino acid) into a nonsense codon (one that terminates translation).
silent mutation
A mutation that changes a codon to another codon that specifies the same amino acid
neutral mutation
A missense mutation that alters the amino acid sequence of the protein but does not change its function
Loss-of-function mutations
Mutations that cause the complete loss or partial absence of normal protein function
Gain-of-function mutations
Mutations which produce an entirely new trait or cause a trait to appear in the wrong place or the wrong time
Conditional mutations
Mutations expressed only under certain conditions
Lethal mutations
Mutations that cause premature death
Suppressor mutation
A genetic change that hides or suppresses the effect of another mutation
Intragenic suppressor mutation
A suppressor mutation in the same gene as that being suppressed
Intergenic suppressor mutation
A suppressor mutation in a different gene as that being suppressed
Mutation rate
The frequency with which a wild-type allele at a locus changes into a mutant allele
3 factors that affect mutation rate
1) The frequency with which the change will take place in DNA
2) The probability that a mutation will be repaired
3) The probability that a mutation will be recognized and recorded
Adaptive mutation
The process where stressful environments induce mutations so the species can survive
Spontaneous mutations
mutations that occur under normal conditions
Induced mutations
Mutations that result from changes caused by environmental chemicals or radiation
