1. DNA: The Blueprints For Life1

2. Chromosomes Recall: Gene Chromosome A segment of DNA
that codes for 1 polypeptide.
Chromosome
A long strand
of DNA tightly coiled to form
a rod-shaped structure.
May contain
hundreds of genes.
Humans have 46 chromosomes
arranged in 23 homologous pairs
Gene 1
Gene 2 2

3. 10.2 Genetic Changes Mutation ANY change in DNA Most are harmful!
A few turn out to be beneficial & provide the variation upon which natural selection acts to cause evolution. 3

4. Mutagens Examples: Environmental factors that damage DNA
(cause mutations)
Examples:
Viruses
Asbestos
Cigarrette tar
Radiation (UV, x-rays, etc)
Chemicals
Ames test
Procedure used by researchers to identify mutagenic substances.

5. There are 2 Categories of Mutations:
Point mutation
Involves a change in 1 base pair
Chromosome mutation
Involves a change in MANY base pairs or even the loss or gain of a entire chromosome.
* Affects many genes (therefore, many proteins) 5

6. There are 2 Types of Point Mutations:
Substitution mutation
One base is substituted for another:
Ex:
THE CAT ATE THE RAT
THE MAT ATE THE RAT 6

7. Affects only 1 codon which may or may not affect the amino acid
Substitution
Affects only 1 codon which may or may not affect the amino acid
“Silent”
RNA 7

8. A single change in amino acid sequence can have disastrous effects:
Sickle-cell Anemia 8

9. Sickle Cell Anemia

10. Sickle Cell Anemia Animation

11. Frameshift Ex: THE CAT ATE THE RAT Addition: THE TCA TAT ETH ERA T
Results from the addition or subtraction of a single base pair.
Ex:
THE CAT ATE THE RAT
Addition: THE TCA TAT ETH ERA T
Subtraction: THE ATA TET HER AT C 11

12. * Affects every codon, therefore, every amino acid after the change!!
Frameshift
* Affects every codon, therefore, every amino acid after the change!! 12

13. There are 5 Types of Chromosome mutations
1. Deletion
A piece of a chromosome breaks off and all the information on that piece is lost 13

14. Chromosome mutations Inversion
A piece of a chromosome breaks off, flips over, and reattaches in reverse
(Segment will be read backwards) 14

15. Chromosome mutations Translocation
A broken piece attaches to a nonhomologous (different) chromosome 15

16. Chromosome mutations Insertion/ Duplication
A broken piece attaches to a homologous (matching) chromosome. 16

17. Chromosome mutations Nondisjunction
Occurs when a pair of homologous chromosomes
fail to separate during meiosis (gamete production) 17

18. Nondisjunction
One gamete gets an extra chromosome. If fertilized the resulting zygote will have three chromosomes instead of a pair - trisomy
Ex: Trisomy 21 or Down’s syndrome
One gamete is short a chromosome. If fertilized, the zygote will have only 1 chromosome instead of a pair- monosomy
Ex: Turner’s Syndrome