1. Mutations

2. Review Questions What is the difference between RNA and DNA?
What is the end result of transcription?
What is the end result of translation?

3. Mutation A change in the sequence of nucleotides within a gene
One or several bases can be added, deleted, or replaced.

4. Mutations
May produce a new trait, a protein that does not work correctly, resulting in structural or functional problems.
May cause positive effects.
May cause negative effects.
May have no effect (silent)

5. What causes mutations?
Mutations often happen when mistakes occur during replication.
Also caused by mutagens like UV light, radiation, and certain chemical toxins.

6. How often do mutations occur?
Mutations are rare events.
The average rate of mutations is one in a million replications.

7. Are you a mutant?
Since DNA replication takes place in your body so many times during your lifetime, at least one of your cells contains a mutation.

8. Types of mutations
substitution: a different base pair replaces the original.
Also known as a point mutation.
Example
-THE DOG BIT THE CAT
- THE DOG BIT THE CAR

9. Types of Point Mutations (aka substitution mutations)
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.
Silent mutation: does not result in an amino acid change in the protein.
How does this happen?

11. Frame Shift Mutations
Frameshift mutation: alters the “reading frame” causing the base triplets that follow it to be changed

12. Frameshift Mutations Two Types:
Insertion: when a base is added to the DNA
Deletion: when a base is deleted from the DNA

13. Frame Shift Mutations Continued
addition or removal of chunks of DNA sequence containing many DNA bases.
Can alter many amino acids in the protein at the same time.

17. Causes Mutagens – radiation, chemicals Examples:
UV light, X-rays, Gamma Rays
Cigarettes, Alcohol, etc.