DNA Repair Mechanisms and Mutations

These flashcards cover key concepts related to DNA repair mechanisms, mutations, and associated terminology.

The SOS system is a DNA repair mechanism that uses __ to continue synthesis when there are many missing or damaged bases.

error-prone DNA polymerase

Methyl-directed mismatch repair helps bacterial cells correct errors in DNA replication by using a __ tag on existing DNA strands.

chemical

Base excision repair results in the removal of a base, leaving an __ site.

AP (abasic)

Nucleotide excision repair is responsible for repairing multiple damaged bases, such as __ dimers.

thymine

Homologous recombination repairs __ stranded breaks in DNA using a process similar to crossing over.

double

In the Ames test, specific strains of __ bacteria are used to determine if a substance is a mutagen.

Salmonella

A __ mutation keeps the amino acid the same but changes a base pair.

silent

A __ mutation codes for a different amino acid.

missense

A __ mutation introduces a stop codon into the sequence, which can have significant effects on the organism.

nonsense

Complementation occurs when two mutations in different genes restore a __ phenotype in a heterozygote.

normal

The cistron is a DNA segment that encodes a __ polypeptide chain.

single

In trans configuration of mutations, two mutations are located on __ DNA molecules.

different

A __ bond links amino acids in a protein chain between the carboxyl and amino groups.

peptide

A __ mutation increases gene function or expression beyond normal levels.

hypermorphic

Ectopic expression occurs when a gene is expressed in the __ place or at the wrong time.

wrong

A nonsense suppressor tRNA can recognize a stop codon and insert an __ instead.

amino acid