28 Mutations

Question

Answer

What is a mutation?

A heritable change in DNA nucleotide sequence.

What is wild type?

The reference or commonly occurring nonmutant genotype/phenotype.

What is a mutant?

A cell lineage that carries an inherited mutation.

What is a base substitution?

One nucleotide base pair is replaced by another.

What is an insertion mutation?

One or more nucleotides are added to a DNA sequence.

What is a deletion mutation?

One or more nucleotides are removed from a DNA sequence.

What is a frameshift mutation?

An insertion or deletion not divisible by three changes the downstream codon reading frame.

What is a silent mutation?

A DNA change that does not change the encoded amino acid.

What is a missense mutation?

A mutation that changes one encoded amino acid.

What is a nonsense mutation?

A mutation that creates a premature stop codon.

Can a mutation be beneficial?

Yes, but beneficial mutations are rare; many are harmful or neutral.

Why do mutations become heritable?

The changed DNA sequence is copied during DNA replication.

Would insertion of three bases necessarily shift the reading frame?

No; adding three bases preserves the downstream codon frame.