Mutations Mutations

Section 12–4Section 12–4This section describes and compares This section describes and compares

gene mutations and chromosomalgene mutations and chromosomalmutations.mutations.

MutationsMutations

What are mutations?What are mutations? Mutations are changes in the DNA Mutations are changes in the DNA

sequence that affect genetic sequence that affect genetic information.information.

MutationsMutations

Is the following sentence true or false? Is the following sentence true or false?

Chromosomal mutations result from Chromosomal mutations result from changes in a single gene.changes in a single gene.

False False

Kinds of Mutations Kinds of Mutations

Mutations that occur at a single Mutations that occur at a single point in the DNA sequence are____ point in the DNA sequence are____ mutations.mutations.

pointpoint

Kinds of MutationsKinds of Mutations

A mutation involving the insertion or A mutation involving the insertion or deletion of a nucleotide is deletion of a nucleotide is a(an)__mutation.a(an)__mutation.

FrameshiftFrameshift

Kinds of MutationsKinds of Mutations

Circle the letter of each sentence that is Circle the letter of each sentence that is true about gene mutations.true about gene mutations.

Point mutations affect just one nucleotide.Point mutations affect just one nucleotide.

Point mutations that involve the insertion Point mutations that involve the insertion or deletion of a nucleotide change the or deletion of a nucleotide change the reading frame of the genetic message.reading frame of the genetic message.

Frameshift mutations affect every amino Frameshift mutations affect every amino acid that follows the point of the mutation.acid that follows the point of the mutation.

Significance of Mutations Significance of Mutations

Mutations that cause dramatic Mutations that cause dramatic changes in protein structure are changes in protein structure are often _____.often _____.

harmfulharmful

Significance of MutationsSignificance of Mutations

Mutations are a source of ____ in a Mutations are a source of ____ in a species.species.

genetic variabilitygenetic variability