Lecture 7 Cycle 4: DNA Mutations and Repair Mechanisms

These flashcards cover key vocabulary terms related to DNA mutations, their causes, and mechanisms of repair, as outlined in the lecture.

Exogenous Sources of DNA Damage

Sources of DNA damage that originate from outside the cell, such as UV light, chemicals, and ionizing radiation.

Endogenous Sources of DNA Damage

Sources of DNA damage that originate within the cell, often from biochemical processes that naturally occur inside.

Thymine Dimers

A type of DNA damage caused by UV light, where two adjacent thymine bases bond together, causing replication issues.

DNA Proofreading

The process by which DNA polymerase checks and corrects mismatched bases during DNA replication.

Mismatch Repair

A repair mechanism that fixes errors made during DNA replication that escape proofreading.

Reactive Oxygen Species (ROS)

Highly reactive molecules formed during metabolic processes that can damage DNA, proteins, and lipids.

Point Mutation

A mutation that involves a change in a single base pair in DNA, also known as substitution.

Insertion Mutation

A mutation caused by the addition of one or more nucleotide bases in a DNA sequence.

Deletion Mutation

A mutation resulting from the loss of one or more nucleotide bases in a DNA sequence.

Transposable Elements

DNA sequences that can move or 'jump' to different positions within the genome, causing genetic variation and sometimes mutations.

Non-Homologous End Joining (NHEJ)

A DNA repair process that directly joins two broken ends of DNA together, often leading to mutations.

Hydroxyl Radical

A reactive oxygen species that is highly reactive and can cause significant damage to DNA.

Gibbs Law of Thermodynamics

The principle stating that systems tend to minimize their free energy, affecting molecular stability and reactions.

Transition Mutation

A point mutation that changes a purine to another purine or a pyrimidine to another pyrimidine.

Transversion Mutation

A point mutation that changes a purine to a pyrimidine or vice versa.

5-bromouracil (5-BrU)

A mutagenic compound that can substitute for thymine in DNA and cause mispairing during replication.

DNA Damage vs. Mutation

DNA damage refers to physical harm that can result in mutations. A mutation is a stable, heritable change in the DNA sequence.

Tautomeric species

are alternative structural forms of a nucleotide that can lead to mispairing during DNA replication.

Keto form

of nucleotides that pairs correctly with adenine during DNA replication. Carbonyl group (C=O)

Enol form

of nucleotides that can misspair with adenine due to a hydroxyl group (C-OH)

Tautomeric equilibrium

Keto and enol forms constantly shift between forms due to their relative stabilities, influencing mutation rates