1. End Show Slide 1 of 24 Copyright Pearson Prentice Hall 12-4 Mutations Outline 12–4: Mutations

2. 12-4 Mutations I. What are mutations? A. Mutations are changes in the genetic material. II. Types of Mutations: A. Gene Mutations 1. Mutations that produce changes in a single gene B. Chromosomal Mutations 1. Mutations that produce changes in whole chromosomes

3. End Show 12–4 Mutations Slide 3 of 24 Copyright Pearson Prentice Hall Kinds of Mutations III. Gene Mutations A. Point mutations 1. Gene mutations involving a change in one or a few nucleotides. They occur at a single point in the DNA sequence. 2. Examples: a. Substitutions = switch one nucleotide b. Insertions = insert one nucleotide c. Deletions = delete one nucleotide

4. End Show 12–4 Mutations Slide 4 of 24 Copyright Pearson Prentice Hall Kinds of Mutations 3. Substitutions a. One nucleotide is substituted for another. b. Usually affect only one amino acid.

5. End Show 12–4 Mutations Slide 5 of 24 Copyright Pearson Prentice Hall Kinds of Mutations 4. Insertion a. Extra nucleotide is inserted into a the DNA sequence. b. Causes a shift in the grouping of codons. c. This is called a frameshift mutation d. May change ALL amino acids in the protein

6. End Show 12–4 Mutations Slide 6 of 24 Copyright Pearson Prentice Hall Kinds of Mutations 5.Deletion a. A single base is deleted and the reading frame is shifted.

7. End Show 12–4 Mutations Slide 7 of 24 Copyright Pearson Prentice Hall Kinds of Mutations IV. Chromosomal Mutations A. These involve changes in the number or structure of chromosomes. B. Examples: 1. Deletions 2. Duplications 3. Inversions 4. Translocations.

8. End Show 12–4 Mutations Slide 8 of 24 Copyright Pearson Prentice Hall Kinds of Mutations C. Deletions 1. Involve the loss of all or part of a chromosome.

9. End Show 12–4 Mutations Slide 9 of 24 Copyright Pearson Prentice Hall Kinds of Mutations D. Duplications 1. Produce extra copies of parts of a chromosome.

10. End Show 12–4 Mutations Slide 10 of 24 Copyright Pearson Prentice Hall Kinds of Mutations E. Inversions 1. Reverse the direction of parts of chromosomes.

11. End Show 12–4 Mutations Slide 11 of 24 Copyright Pearson Prentice Hall Kinds of Mutations F. Translocations 1. Occurs when part of one chromosome breaks off and attaches to another.

12. End Show 12–4 Mutations Slide 12 of 24 Copyright Pearson Prentice Hall Significance of Mutations V. Significance of Mutations Many mutations have little or no effect on gene expression. Some mutations are the cause of genetic disorders. Beneficial mutations may produce proteins with new or altered activities that can be useful. Polyploidy is the condition in which an organism has extra sets of chromosomes.