1. Muscular Distrophy
A single extra chromosome (Chr. 21) can cause Down Syndrome.
Type 1 Tyrosinemia
Tay-Sachs Disease
Nyhan Syndrome
Trisomy-18
Sickle Cell Anemia
Huntington’s Disease
A few wrong letters (A, T, C, or G) can cause…
Color Blindness
Hemophilia
Cystic Fibrosis

3. We need to be able to…
- Pass it to our children
- Split it in half
- Read it
- Build correct proteins
- Copy it
- Separate copies during mitosis
… all without any mistakes!

4. We need to be able to…
- Pass it to our children
- Split it in half
- Read it
- Build correct proteins
- Copy it
- Separate copies during mitosis
… all without any mistakes!
A real chromosome contains about million pairs of letters!

6. Take out a blank sheet of paper, label it Page 308: Genetic Mutations

8. What is a Genetic Mutation?
A genetic mistake; a permanent change in the DNA code, such that the code differs from its parents

9. What is a Genetic Mutation?
A genetic mistake; a permanent change in the DNA code, such that the code differs from its parents
X-RAY

10. What is a Genetic Mutation?
A genetic mistake; a permanent change in the DNA code, such that the code differs from its parents

11. What is a Genetic Mutation?
A genetic mistake; a permanent change in the DNA code, such that the code differs from its parents
The Two Types:
“Hereditary” mutations occur during reproduction; present throughout a person’s life in every cell in the body.
Examples: Down syndrome, cystic fibrosis, color blindness, etc.
“Hereditary”
“Acquired”
“Acquired” mutations occur at some time during a person’s life; present only in specific cells.
Examples: Skin cancer, lung cancer, etc.

14. How Common Are Mutations?
“Every time human DNA is passed from one generation to the next it accumulates new mutations” (Nature, 2009).
Hereditary Mutations:
inherited mutations per baby
2-4 mutations per chromosome
Acquired Mutations:
Human code has 6 billion letters (A, T, G, C)
Average cell has 3 mutations
Most don’t harm anything!

16. The code for tyrosine (TAT) switched to asparagine (GAT).
An Ancient Example:
Originally, all humans had brown eyes. Then, about 8,000 years ago, a mutation occurred…
The code for tyrosine (TAT) switched to asparagine (GAT).
Less tyrosine (which turns brown) led to blue-colored eyes, which see slightly-better at night but slightly worse during the day. Amazingly, this mutation occurred in only one single human. Thus, all blue-eyed people are related!

18. Mutations and Aging
“Our study… suggests that accumulated alterations in the structure of DNA may be a major underlying cause of cellular aging. This begs the question of whether we can reverse… age-related declines and diseases.” J. Belmonte, Salk Institute

20. Rolling the Dice… Get out Page 305.
Come up and roll the four dice to decide which chromosome will have a mutation.
Pick a card and read it to the class.
Add the mutation to Page 305.