DNA Mutation and Repair

Mutation

A change in the DNA sequence that can affect an organism's phenotype.

Transition base substitution

A mutation where a purine is replaced with another purine or a pyrimidine is replaced with another pyrimidine.

Transversion base substitution

A mutation where a purine is replaced with a pyrimidine or vice versa.

Spontaneous mutation

Naturally occurring mutations that arise in all cells.

Induced mutation

Mutations that occur due to exposure to external agents known as mutagens.

Frameshift mutation

A mutation caused by indels (insertions or deletions) that shift the reading frame of the genetic code.

DNA repair mechanisms

Biological processes by which a cell identifies and corrects damage to its DNA.

Pyrimidine dimer

A type of DNA damage caused by UV light, leading to covalent bonding between adjacent thymine or cytosine bases.

Base excision repair

A DNA repair pathway that removes and replaces damaged or incorrect bases in DNA.

Nucleotide excision repair

A DNA repair mechanism that removes a wide range of DNA damage, including bulky adducts.

Xeroderma pigmentosum

An autosomal recessive disorder characterized by an inability to repair DNA damage caused by UV light.

Ethidium bromide

A chemical compound used as a visualizing agent in gel electrophoresis, which acts as an intercalating agent causing mutations.

Methylation

A modification of DNA where a methyl group is added, influencing gene expression and repair processes.

Point mutations

Mutations that affect a single nucleotide or a few adjacent nucleotides in the DNA sequence.

Reactive oxygen species (ROS)

Chemically reactive molecules containing oxygen that can cause damage to DNA.

CpG island

A region of DNA where a significant number of cytosine and guanine nucleotides occur in close proximity, often associated with gene regulation.

Mismatch repair

A DNA repair mechanism that corrects mismatched base pairs that occur during DNA replication.

Intercalating agents

Chemical substances that insert themselves between base pairs in DNA, leading to mutations.

Deamination

The removal of an amine group from a nucleotide, potentially causing transitions in base pairing.

Depurination

The loss of a purine base (adenine or guanine) from the DNA molecule, often leading to mutations.