1. The Cell Cycle

2. 13.3 Mutations
Mutations – heritable changes in genetic information (changes to the DNA sequence)
Two types - gene and chromosomal mutations
Mutations can be caused by chemical or physical agents (mutagens)
Chemical – pesticides, tobacco smoke, environmental pollutants
Physical – X-rays and ultraviolet light

3. 13.3 Mutations Gene mutations
Point Mutation: mutations that affect a single nucleotide
Frameshift mutation: shift the reading frame of the genetic message.
Can change the entire protein so it doesn’t work
Gene Mutations Explained

4. 13.3 Mutations

5. 13.3 Chromosomal Mutations
Chromosomal mutation: mutation that changes the number or structure of chromosomes.

6. 13.3 Chromosomal Mutations
Types of chromosomal mutations:
Deletion: The loss of all or part of a chromosome
Duplication: A segment is repeated
Inversion: part of the chromosome is reverse from its usual direction.
Translocation: one chromosome breaks off an attaches to another chromosome.

7. Karyotype of a normal male
Nondisjunction
Karyotype of a Patau’s male (notice chromosome #13 has three chromosomes instead of two)
Karyotype of a normal male

8. Silent and nonsense mutations
Silent: an alteration in a DNA sequence that does not result in an amino acid change because many codons code for the same amino acid. For instance: GAA and GAG both code for amino acid GLU
Nonsense mutation: replacement of one base in the DNA code results in a “stop” codon therefore shortening the protein.