1. Genes & Mutations

2. Review: Genes Humans have: 23 pairs (46 total) chromosomes

3. Review: Gene Expression
section of a chromosome which codes for a trait
Ex:
Gene codes for your hair color

4. Review: Cell Cycles During S-phase of interphase
Usually DNA replicates perfectly:
Mitosis (parent  daughter cell)
Meiosis (parent  gamete cell)

5. Mutations
Any change in the genome (nitrogen base sequence) resulting from errors during DNA replication and environmental conditions.

6. Small Scale Mutations

7. Small Scale Mutations Sometimes an error occurs during replication
Changes occur in nitrogen bases 7

8. Causes of Mutations Replication Errors: Environmentally Errors:
~50 mutations from your parents
Environmentally Errors:
UV light, cigarettes… 8

9. Ex: Cystic Fibrosis Deletion (3 bases) in gene that codes for CFTR
508th amino acid phenylalanine is removed
Malfunctioning transport protein Cl- ions
Causes mucus buildup in lungs, digestive tract

10. Ex: Beneficial Mutation
Deletion of a gene that codes for CCR5
Protein is important in immune function
Results in HIV resistance in homozygotes

11. Ex: Sickle Cell Anemia Substitution in the gene that codes for Hgb.
Thymine replaced with adenine
Results in valine instead of glutamine
Hgb folds incorrectly
RBCs become sickle shaped

12. Large Scale Mutations

13. Karyotypes A picture of an organisms complete set of chromosomes
A human karyotype contains:
46 total chromosomes (23 homologous pairs)
#1-22: Autosomes
#23: Sex chromosomes

14. Wolf Karyotype (2n=78)

15. Analyzing a karyotype What information does a karyotype show?
Total number of chromosomes
The gender of the individual
Chromosomal mutations (genetic diseases)

16. Large Scale Mutations
Any change in chromosome number resulting from errors during gamete formation (meiosis)

17. Ex: Trisomy 21 An individual receives an extra 21st chromosome
Causes Down’s Syndrome
1:700 births

18. Ex: Trisomy 13 An individual receives an extra 13th chromosome
Causes Patau Syndrome
1:10,000 births
80% children die w/in 1 year

19. XXY Syndrome Males receive an extra X chromosome
Causes Klinefelter’s Syndrome
1:1,000 births
Males are sterile

20. XYY Syndrome Males receive an extra Y chromosome.
Causes Jacob’s Syndrome
1:1,000 births
Males are overly aggressive

21. Monosomy X Syndrome Females receive only one X chromosome
Causes Turner’s Syndrome
1:5,000 births
Females are sterile