Mutations and Genetic Variation

Mutation

Random changes in the DNA sequence that can affect an organism.

mRNA Reading Frame

The sequence of nucleotides that codes for protein and is read by the ribosome.

Central Dogma of Biology

The process by which DNA is transcribed into RNA, which is then translated into protein.

Point Mutation

A mutation that usually involves a change in 1 to 3 nucleotides affecting a single gene.

Chromosomal Mutation

Mutations that occur during meiosis and affect large sections of chromosomes.

Base-Pair Substitution

Replaces one nucleotide and its partner with another pair; can cause synonymous, missense, or nonsense mutations.

Silent Substitution Mutation

A change in a single nucleotide that doesn’t result in a change in amino acid sequence.

Missense Mutation

A change in a single nucleotide that results in a change in a single amino acid in the sequence.

Nonsense Mutation

A change in a single nucleotide that results in a premature stop codon in the mRNA sequence.

Frameshift Mutation

Alters reading frame due to insertion or deletion of nucleotides, changing all codons translated after the mutation.

Mutagen

Physical or chemical agents that can cause mutations.

Genetic Variation in Eukaryotes

Generated through sexual reproduction, including independent assortment and crossing over.

Prokaryotic Genetic Variation: Transformation

Process where bacterial cell uptakes naked DNA from its surroundings.

Prokaryotic Genetic Variation: Transduction

Introduction of foreign bacterial DNA into a cell by a bacteriophage.

Prokaryotic Genetic Variation: Conjugation

Transmission of DNA between bacterial cells through direct contact.

Prokaryotic Genetic Variation: Transposition

Relocation of DNA segments within the same or different DNA molecule.