Genetic Mutations: Classification, Mechanisms, and Functional Effects

Practice flashcards covering DNA mutation types, mechanisms, and effects based on lecture notes.

ALS (Lou Gehrig's Disease)

A muscle wasting disease caused by a mutation known as a repeat expansion, which changes or destroys the function of the protein it is within.

Repeat Expansion

A mutation where repeated sequences of DNA within genes increase in number; once they reach a critical point, they can alter protein function.

Strand Slippage

An error during DNA replication where polymerase replicates a region multiple times due to the folding or bending of the DNA template or daughter strand.

Mutation

A change to the nucleotide sequence that is heritable and capable of being passed down through mitosis or meiosis.

Somatic Mutation

A mutation occurring in body cells that affects the individual but is not passed on to the next generation.

Germline Mutation

A mutation occurring in gamete-producing cells that is passed down to $50\%$ of the offspring and appears in every cell of those progeny.

Single Nucleotide Polymorphism (SNP)

A single base substitution or nucleotide change; it is the primary form of genetic variation among humans.

Haplotype

A specific collection of individual Single Nucleotide Polymorphisms (SNPs) possessed by an individual.

Human Genetic Variation

The amount of variation across the entire human genome, which is approximately $0.1\%$, meaning humans are $99.9\%$ similar.

Transition

A base substitution where a purine is replaced by another purine, or a pyrimidine by another pyrimidine, maintaining the diameter of the DNA double helix.

Transversion

A base substitution where a purine is replaced by a pyrimidine, or vice versa, which changes the shape and diameter of the double helix.

Indel

A shorthand term for the insertion or deletion of one or more base pairs in a DNA sequence.

Frameshift Mutation

A mutation caused by the addition or deletion of one or two base pairs, which shifts the entire reading frame of the ribosome from that point forward.

Missense Mutation

A base substitution that results in the replacement of one amino acid with a different amino acid.

Neutral Missense Mutation

A missense mutation where the original amino acid is replaced by one with similar chemical activity, often resulting in minimal or no change to protein function.

Nonsense Mutation

A mutation that changes a codon for an amino acid into a stop codon, resulting in a truncated protein.

Silent Mutation

A base substitution that changes the DNA sequence but does not change the amino acid sequence due to the degeneracy of the genetic code.

Loss of Function Mutation

Also known as a null mutation, this destroys the function of a protein and typically behaves as a recessive allele.

Gain of Function Mutation

A mutation that increases the amount or activity of a protein; these often behave as dominant alleles and are associated with oncogenes.