Lecture 6: Sources of Genetic Variation: Mutation Flashcards
The genetic substrate for natural selection AND the Raw Material for Evolution
Mutation is the __ __ for natural selection and the __ __ for evolution
- genetic substrate
- raw material
If there is no __ __ neither genetic drift nor natural selection would be able to change allele frequencies, because there would be nothing to change
- genetic variation
Sources of Genetic Variation (2)
- Mutations (changes in the genetic code)
- Sex (Meiosis)
Shuffling of combinations of alleles along a chromosome
Genetic Recombination
Shuffling of combinations of haploid chromosomes into new genotypes
Random Mating
Sex: No novel alleles, only novel __
genotypes
Types of Mutations (4)
1) At the Nucleotide Level (Point mutations)
2) At the “Gene” Level
3) At the Chromosome Level
4) At the Genome Level
Types of mutations at the nucleotide level (point mutations) (3)
– Single nucleotide substitutions (transitions, transversions)
– Insertion (nucleotide insertion)
– Deletion (nucleotide deletion)
Types of mutations at the “gene” level (3)
– Gene Insertions (Gene Duplications, transposons, horizontal gene transfer)
– Gene Deletions (pseudogenization, transposons)
– Exon Shuffling
Types of mutations at the chromosome level (4)
- Chromosome duplications
- Chromosome deletions
- Chromosome inversions
- Chromosome fusions
Types of mutations at the genome level (2)
– autopolyploidization
– allopolyploidization
What are the two main types of mutations within functional coding regions of the genome?
- Structural mutations
- regulatory mutations
What does a structural mutation affect?
It changes the actual coding region of the gene.
A type of mutation within functional coding regions of the genome that changes the actual coding region of the gene.
Structural mutation
A type of mutation within functional coding regions of the genome that alters gene regulation processes, such as gene expression (transcription, RNA processing, translation, etc.).
Regulatory mutation
What are the primary effects of structural mutations? What are the secondary effects of structural mutations?
- Changes in amino acid composition (amino acid substitutions).
- Changes in the secondary, tertiary, and quaternary structure of proteins.
What does a regulatory mutation affect?
It alters gene regulation processes, such as gene expression (transcription, RNA processing, translation, etc.).
__ mutations = single nucleotide change
Point
How do point mutations occur during DNA replication?
Due to errors during mitosis or meiosis by DNA and RNA polymerases, or reverse transcriptase.
How can point mutations arise from repair processes?
Errors in the repair of sites damaged by mutagens, such as UV light or chemicals.
Which type of nucleotide mutations are more common?
Transitions
__ involve mutations between nucleotides of similar structure (purines to purines or pyrimidines to pyrimidines), while __ involve mutations between nucleotides of different structures.
- Transitions
- transversions
What is the difference between transitions and transversions?
Transitions involve mutations between nucleotides of similar structure (purines to purines or pyrimidines to pyrimidines), while transversions involve mutations between nucleotides of different structures.
Why are transitions hypothesized to be less disruptive to DNA structure?
Because transitions involve mutations between nucleotides of similar structure, they cause less disruption of the DNA helical structure and are less detectable by DNA polymerase or mismatch repair enzymes.