Mutations Lesson

Mutations

A mutation describes a change in the sequence of nucleotides (letters) in a segment of DNA. 

This can occur due to errors in DNA replication, cell division, or exposure to certain environmental agents.

Mutations in DNA

Mutations Can Be

• Harmful - Causes an enzyme or protein to not function properly

• Helpful - Causes a genetic change that is good for the individual/species

• Neutral (not good or bad) - Doesn't do anything

Multiple Choice

A mutation is defined as:

• A change in the cell's structure

• Anything that changes in an embryo

• Any change in the physical features of a human

• A change in the DNA sequence

A substitution mutation describes a change in the nucleotide sequence in which one nucleotide is replaced by another. 

This is the most common type of mutation and is also known as a point mutation.


Point mutations may or may not have an effect on the amino acid sequence

Substitution Mutations

Insertion Mutation

An insertion mutation describes a change in the nucleotide sequence in which one or more additional nucleotides are inserted into the sequence. 

This will change the amino acid sequence in protein synthesis.

A deletion mutation describes a change in the nucleotide sequence in which one or more nucleotides are omitted from the sequence. 

This will change the amino acid sequence in protein synthesis.

​Deletion Mutation

Insertion and deletion mutations are also referred to as frameshift mutations. 

Remember that in protein synthesis the mRNA is read one codon at a time so the nucleotides must be looked at in sets of 3.
 

When a nucleotide is added or removed, the reading frame shifts, resulting in multiple changes to the amino acid sequence following the site of the mutation.

Frameshift Mutation

Multiple Choice

A point mutation is usually what type of mutation

• Frameshift

• Insertion

• Deletion

• Substitution

Multiple Select

A frameshift mutation is which of the following?

• Point mutation

• Insertion

• Deletion

• Subtitution

Multiple Choice

Which mutation would be more harmful for an organism?

• Point mutation (substitution)

• Frameshift (insertion/Deletion)

Multiple Choice

Why would a frameshift be more harmful?

• It changes all the code downstream

• Only one nucleotide is changing

• All mutations are harmful

• It can't correct iself

Multiple Choice

What mutation has occurred here?

T-G-A-C-C-A

T-G-A-G-C-A

• Substitution

• Deletion

• Insertion

• Frameshift

Multiple Choice

ATTTGAGCC- Original

ATTGAGCC - Mutated

The example above is an example of a

• Insertion- Frameshift

• Deletion- Substitution

• Deletion -Frameshift

• All of the above

Multiple Choice

Would a Somatic mutation or a Gametic mutation have a more significant impact on the species?

• Gametic mutation
• Somatic mutation

Multiple Choice

Why would a gametic cell mutation have a larger impact on the species?

• It can be passed on to the next generation through reproduction.
• It has no impact on the species' genetic diversity.
• It can only be passed on through asexual reproduction.
• It only affects the individual and not the species as a whole.