What Is A Mutation (Page 2 of 3) in pdf

What Is A Mutation Page 2

What types of mutations can occur?

Point mutations are single-base changes in a gene's DNA sequence. This type of mutation can change a

protein in the following ways:

•

Missense mutations result in a single amino acid change within a protein.

•

Nonsense mutations create a premature "translation stop signal" (or "stop codon"), causing the gene's

protein product to be shortened.

•

A third type of mutation, called a silent mutation, does not result in an amino acid change. We’ll

explore how this happens when we look at the "genetic code" below.

Frameshift mutations result from insertion or deletion of a more than one base into the DNA sequence. This

alters the grouping of nucleotide bases into three-base codons, causing a shift of "reading frame" during the

translation process.

Insertions and deletions add or remove chunks of DNA sequence containing many DNA bases. These

mutations alter many amino acids in the protein at the same time.

Activity 2. Mutate a gene!

It's time to try your hand at mutating a DNA sequence.

1. Observe the original DNA sequence listed below. Using your mRNA codon chart or the figure on page 230

of your textbook, write the amino acid sequence of the resulting protein.

Original DNA Sequence:

ATG TGC CTC

mRNA Sequence:

__________________________________________________

Amino Acid Sequence:

__________________________________________________

What Is A Mutation Page 2