1. Mutations

2. What Are Mutations?
Mutation: Changes in the nucleotide sequence of DNA
Mutagen: A physical or chemical agent that changes DNA
Mutation May occur in:
somatic cells (body cells): will not be passed to offspring
gametes (eggs & sperm): can be passed to offspring

3. Are Mutations Helpful or Harmful?
Mutations happen regularly
Some mutations may improve an organism’s survival (beneficial): It can be a source of genetic variability in a species
Almost all mutations are neutral :They won’t affect the protein sequence
Many mutations are repaired by enzymes
Chemicals & Radiation cause mutations:
-e.g. Chemicals: Chlorine, Hydrogen peroxide (H2O2), Benzene
Radiation: UV light, alpha ray, beta ray gamma ray

4. Types of Mutations There are 2 types of mutations:
Gene mutation: result from changes in a single gene
Chromosome mutation: mutations involve changes in whole chromosomes

5. Gene Mutation There are 2 types of gene mutations:
Point mutations: Mutations that affect one or more nucleotide
- e.g. substitutions, insertions, deletions
Frameshift mutations: Mutations that shift the reading frame of the genetic message
- e.g. Insertions, deletions

6. Point Mutation Point Mutations – changes in one or a few nucleotides
Substitution
THE FAT CAT ATE THE RAT
THE FAT HAT ATE THE RAT
Insertion
THE FAT CAT XLW ATE THE RAT
Deletion
THE FAT ATE THE RAT

7. Point Mutation Disease
Sickle Cell Anemia is the result of one nucleotide substitution
It Occurs in the hemoglobin (A protein in red blood cell) gene

8. Frameshift Mutation
Frameshift Mutations – shifts the reading frame of the genetic message so that the protein may not be able to perform its function and it is often harmful
Insertion
THE FAT CAT ATE THE RAT
THE FAT HCA TAT ETH ERA T
Deletion
TEF ATC ATA TET GER AT

9. Chromosome Mutations
Chromosome mutations: Changes in number and structure of entire chromosomes
There are 5 types of chromosome mutations:
Deletion
Duplication
Inversion
Translocation
Nondisjunction

10. Deletion and Duplication
Deletion: Due to breakage, A piece of a chromosome is lost
Duplication: Occurs when a gene sequence is repeated

11. Inversion
Inversion: Chromosome segment breaks off and then flips around backwards and reattaches

12. Translocation
Translocation: Involves two chromosomes that are not homologous, part of one chromosome is transferred to another chromosomes

13. Nondisjunction
Nondisjunction: Failure of chromosomes to separate during meiosis, causes gamete to have too many or too few chromosomes