Lesson 6: Mutation Flashcards
- genetic substrate for natural selection
- raw material for evolution
mutation
What reduces variation?
- genetic drift in finite populations
- reduction in allelic diversity
- reduction in heterozygosity (inbreeding)
Sources of allelic variation
mutation
Sources of Genotypic Variation
Sex (meiosis)
heritable variation changes in gene expression without changes in genetic code
epigenetic inheritance
if there is no __ __, neither genetic drift nor natural selection would be able to change allelic frequencies, because there would be nothing to change
genetic variation
requires genetic variation upon which it could act
natural selection
- change in genetic code
- new alleles and/or new genes
mutations
Mutations: new alleles
nucleotide substitutions, insertions, deletions
Mutations: new genes
- gene duplication or deletions
- exon shuffling
- horizontal gene transfer (not always considered mutation)
Types of Mutations
- chromosomal duplications or deletions
- deletions of large chromosomal regions
- chromosomal inversions
- whole genome duplication
- no novel alleles
- only novel genotypes
sex
Sex
- genetic recombination
- random mating
shuffling of combinations of alleles along a chromosome
genetic recombination
shuffling of combinations of haploid chromosomes into new genotypes
random mating
Types of Mutations:
AT THE NUCLEOTIDE LEVEL
- single nucleotide substitutions
- insertions
- deletion
mutation at the nucleotide level is also called…?
point mutations
types of single nucleotide substitutions
- transitions
- transversions
Types of Mutations:
AT THE “GENE” LEVEL
- gene insertions
- gene deletions
- exon shuffling
Types of gene insertions
- gene duplication
- transposons
- horizontal gene transfer
Types of gene deletions
- pseudogenization
- transposons
Types of Mutations:
AT THE CHROMOSOME LEVEL
chromosome
- duplications
- deletions
- inversions
- fusions
Types of Mutations:
AT THE GENOME LEVEL
- autopolyploidization
- allopolyploidization
changes in the actual coding region of the gene
structural
structural
- primary
- secondary, tertiary, quaternary structure
primary structure
amino acid composition (amino acid substitutions)
changes in gene regulation
regulatory
regulatory
gene expression
gene expression
- transcription
- RNA processing
- translation
single nucleotide change
point mutations
Causes of Point mutations
- DNA replication error during mitosis or meiosis
- Error in repair of sites damaged by mutagens
nucleotide composition
- phosphate group
- nitrogenous base
- 5’-carbon sugar