1. Chapter 12 Section 4 Mutations

2. Mutations DNA contains the code of instructions for cells. Sometimes, an error occurs when the code is copied. - Such errors are called mutations. Mutations are changes in the genetic material.

3. 2 Types of Mutation 2 types: 1.Gene mutation  produce changes in a single gene 2.Chromosomal mutation  produce changes in whole chromosomes

4. Gene Mutations Point mutation  gene mutations involving changes in 1 or a few nucleotides - Occurs at a single point in the DNA sequence Includes: a. Substitutions  1 base changed to another b. Insertions  a base is inserted or added c. Deletions  a base is deleted or removed

5. Cont. Gene Mutations SubstitutionInsertion Deletion Substitutions usually affect no more than a single amino acid The effects of insertions/ deletions can be much more dramatic.

6. Cont. Gene Mutations Frameshift mutations  a change that shifts the “reading frame” of the genetic message (caused insertion/ deletion) - By shifting the reading frame, frameshift mutations may change every amino acid that follows the point of mutation. - Can alter a protein so much that it is unable to perform its normal function

8. Gene Mutation Picture of “Mighty Belgium Blue” cattle - Alter in myostatin gene - Produces meatier cattle/ 20% more meat per animal on roughly the same food intake as ordinary animals

9. Chromosomal Mutations Changes in the number or structure of chromosomes a. Deletions  involves loss of all or part of a chromosome b. Duplication  produce extra copies of parts of a chromosome c. Inversions  reverse the direction of parts of a chromosome d. Translocation  when part of a chromosome breaks off & attaches to another

11. Significance of Mutations a)Harmful mutations - Produce defective proteins that disrupt normal biological activities - Causes genetic disorders - Associated with many cancers b) Beneficial mutations - Produce proteins w/ new/ altered activities that can be useful to organisms in different/ changing env - Source of genetic variability in species - Polyploidy  an organism w/ extra sets of chromosomes Ex: polyploid plants are often larger & stronger then diploid plants (bananas & many citrus fruits)

12. Polyploid