DNA and Mutation

This set of flashcards covers key concepts, definitions, and examples related to DNA mutations and their effects.

What is a mutation?

A heritable change in the genetic material.

What is a positive outcome of mutations?

They provide allelic variation and are the foundation for evolutionary change.

What is a negative outcome of mutations?

New mutations may be harmful and are more likely to be harmful than beneficial.

What can mutations affect in gene structure and function?

Changes in chromosome structure, chromosome number, and DNA of a single gene.

What are spontaneous mutations?

Errors in natural biological processes that occur even in healthy, uncontaminated cells.

What are induced mutations?

Mutations caused by agents in the environment, such as radiation, chemicals, and biological agents.

What are the types of nucleotide substitution mutations?

Transitions (purine to purine or pyrimidine to pyrimidine) and transversions (purine to pyrimidine or vice versa).

What is a point mutation?

A mutation that changes a single base pair, which can be a substitution, insertion, or deletion.

What is the Philadelphia chromosome?

A mutation formed when chromosome 9 and chromosome 22 break and exchange parts, leading to a fusion gene associated with chronic myelogenous leukemia.

What is a silent mutation?

A base substitution that does not alter the amino acid sequence of the polypeptide.

What is a missense mutation?

A base substitution that alters the amino acid sequence, which may affect protein function.

What is a nonsense mutation?

A base substitution that changes a normal codon to a stop codon, leading to a truncated protein.

What are frameshift mutations?

Mutations involving the addition or deletion of nucleotides that is not divisible by three, altering the reading frame.

What is the significance of the CFTR gene in cystic fibrosis?

CFTR gene mutations lead to the malfunctioning of the chloride channel, causing thick mucus in cystic fibrosis.

What is the difference between forward and reverse mutations?

Forward mutations change wild-type genotype to new variations, while reverse mutations revert mutant alleles back to wild-type.

What defines deleterious mutations?

Mutations that decrease the chances of survival, with lethal mutations being the most extreme.

How can the effects of a mutation be reversed?

Through back mutations, insertions can revert by deletion, but deletions cannot revert.

What is true reversion?

A mutation that restores the original sequence of the DNA.

What does second-site reversion mean?

A second mutation that suppresses the effect of a first mutation within the same gene.

What is a suppressor mutation?

A mutation in a second gene that bypasses the effect of a mutation in the first gene.