Unit 6 Notes:

Mutations

(1) What Are Mutations?• Mutations: Any change in the sequence of

nitrogenous bases.

• Types:– Missense vs. Nonsense– Point (Substitution, Deletion, Insertion)– Frameshift

• Causes:– Cell errors– Chemical / UV exposure

(2) Types of Mutations• Missense: Mutation changes type of protein made.• Nonsense: Mutation causes premature stop in

translation.• Silent: Changes bases, but has no effect on protein made.

• Point: Change 1 base along DNA sequence.– Substitution Replace 1 base with a different one.– Insertion Add 1 extra base into sequence.– Deletion Remove 1 base from the sequence.

• Frameshift: Any Insertion or Deletion mutations which shift the bases, changing the amino acid sequence.

(3) Mutation Examples:

DNA Template: TAC—GCG—AAA—ACT

1. Insertion:2. Deletion:3. Substitution:

4. Which of the above is/are Frameshift?5. Which of the above is/are missense?6. Which of the above is/are nonsense?