Chp 11

What is the mutation rate determined by?

Counting the number of mutations affecting a phenotype and determining the frequency of mutations per base pair.

How are mutations generally viewed in genomes?

Mutations are rare but genomes are considered to be stable.

What are point mutations?

Mutations that occur at a specific position in a gene, altering the amino acid sequence or affecting gene expression levels.

What are silent mutations?

Mutations that do not change the protein produced, maintaining the overall function of the gene.

What is a synonymous mutation?

A type of silent mutation where a change in the nucleotide sequence does not alter the amino acid sequence of the protein.

What is a missense mutation?

A type of point mutation where a single nucleotide change results in the substitution of one amino acid for another.

What is a nonsense mutation?

A type of point mutation that results in a premature stop codon, leading to a truncated protein and often a loss of function.

What is a frameshift mutation?

A mutation caused by insertions or deletions of nucleotides that shifts the reading frame of the codons.

What is triplet repeat expansion?

A mutation characterized by the increase in the number of times a specific DNA sequence is repeated.

What is depurination?

The loss of a purine base from the DNA molecule, which can result in mutations during replication.

What is an apurinic site?

A site in DNA that has lost a purine base due to depurination.

What is deamination?

The removal of an amino group from a nucleotide, converting cytosine into uracil.

What kind of mutations can alkylating agents cause?

Base substitution mutations.

What is photoreactive repair?

A DNA repair mechanism that uses visible light to repair damage caused by ultraviolet light.

What is nucleotide excision repair?

A DNA repair mechanism that removes damage from DNA.

What percentage of the human genome is made up of transposable DNA?

Nearly half, approximately 47 or 48%.

In the given example, which sequence represents a nonsense mutation?

5’ - TAG AAA ATA CAG CGG - 3’ (TAC is changed to TAG, which is a stop codon).