Bio Mutations

Mutation

change that occurs in our DNA sequence, either due to

• mistakes when DNA is copied

• as a result of environmental factors, such as sunlight

What can be altered in a number of different ways?

the DNA sequence of a gene

What do the varying effects of health that gene mutations have depend on?

• where they occur

• whether they alter the function of essential proteins

What are the types of gene mutations?

• Point mutations

• Frameshift mutations

Types of point mutations

• silent

• missense

• nonsense

Types of frameshift mutations

• addition (insertion)

• deletion

Point mutations (or substitution)

a genetic mutation where a single nucleotide base is changed in a DNA or RNA sequence

Silent mutation

• mutation in the DNA that does not have an observable effect on the organism’s phenotype

• they are a specific type of neutral mutation

Nonsense mutation

a change in one DNA base pair

• Instead of substituting one amino acid for another, the altered DNA sequence prematurely signals the cell to stop building a protein

• This type of mutation results in a shortened protein that may function improperly or not at all

In a nonsense mutation, instead of substituting one amino acid for another, what happens?

the altered DNA sequence prematurely signals the cell to stop building a protein

What does a nonsense mutation result in?

a shortened protein that may function improperly or not at all

Missense mutation

a change in one DNA base pair that results in the substitution of one amino acid for another in the protein made by a gene

Frameshift mutations

• This type of mutation occurs when the addition or loss of DNA bases changes a gene’s reading frame

• A reading frame consists of groups of 3 bases that each code for one amino acid

• A frameshift mutation shifts the grouping of these bases and changes the code for amino acids

• The resulting protein is usually nonfunctional

• Insertions, deletions, and duplications can all be frameshift mutations

When does a frameshift mutation occur?

when the addition or loss of DNA bases changes a gene’s reading frame

How many bases does a reading frame consist of?

3 bases that code for 1 amino acid

What does a frameshift mutation do to the grouping of the bases?

shifts the grouping of these bases → changing the code for the amino acid

What is the result of a frameshift mutation?

usually a nonfunctional protein

What can be frameshift mutations?

• insertions

• deletions

• duplications

Deletion

changes the number of DNA bases by removing a piece of DNA

• Small deletions may remove one or a few base pairs within a gene, while larger deletions can remove an entire gene or several neighboring genes

• The deleted DNA may alter the function of the resulting protein(s)

What is the difference between small deletions and larger deletions

• small deletions may remove one or a few base pairs within a gene

• larger deletions can remove an entire gene or several neighboring genes

What may the deleted DNA alter in a deletion mutation?

it may alter the function of the resulting protein(s)

Insertion

changes the number of DNA bases in a gene by adding a piece of DNA

What happens as a result of an insertion mutation?

the protein made by the gene may not function properly