1. DNA: The Blueprints For Life1

2. 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. 2

3. 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) 3

4. 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 4

5. 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 5

6. Substitution Mutation
mRNA: AUG AAG UUU GGC UAA
protein: met lys phe gly stop
mRNA: AUG AAG UUU AGC UAA
protein: met lys phe ser stop

7. A single change in amino acid sequence can have disastrous effects:
Sickle-cell Anemia 7

8. Sickle Cell Anemia

9. 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 9

10. * Affects every codon, therefore, every amino acid after the change!!
Frameshift
* Affects every codon, therefore, every amino acid after the change!! 10

11. mRNA: AUG AAG UUU GGC UAA
Frameshift Mutation
mRNA: AUG AAG UUU GGC UAA
protein: met lys phe gly stop
mRNA: AUG AAU UUG GCU AA…
protein: met asn leu ala …

12. 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 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

19. 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.

20. DNA: The Blueprints For Life