1. April 21, 2011 Why is DNA double stranded?
If I compared the DNA of a human to that of a whale, what similarities would they have? Differences?
*** Bring up the handout from the BOOK (“Study Guide”); make sure your name is on it!

2. Mutations What are they? Can be Changes in DNA or RNA Sequence
Beneficial
Sickle Cell Anemia carriers are less likely to contract malaria
Ability to digest lactose
Neutral
Harmful
Genetic disorders

3. Mutations
Can only be passed to future generations if they occur in a sex cell
Aka gamete
Sperm/egg

4. Types of Mutations: Least Harmful
Point mutations
Change in one base only
Results in one amino acid change, early stop of translation, or no change at all
Three types
Silent
Missense
Nonsense

5. Types of Mutations: Least Harmful
Silent mutation
One base changes, no change in amino acid
Original DNA: ATACGGCATGGGCACTAGG
Original mRNA: UAUGCCGUACCCGUGAUCC
Original AA: M, P, Y, P, Stop
Mutated DNA: ATACGGCATGGGGACTAGG
Mutated mRNA: UAUGCCGUACCCCUGAUCC
Mutated AA: M, P, Y, P, Stop

6. Types of Mutations: Least Harmful
Missense mutation
One base changes and one amino acid changes
Original DNA: ATACGGCATGGGCACTAGG
Original mRNA: UAUGCCGUACCCGUGAUCC
Original AA: M, P, Y, P, Stop
Mutated DNA: ATACGGCAGGGGCACTAGG
Mutated mRNA: UAUGCCGUCCCCGUGAUCC
Mutated mRNA: M, P, S, P, stop

7. Epidermolysis bullosa
Sickle Cell Anemia
Some forms of Cystic Fibrosis (respiratory) & ALS (Lou Gehrig’s Disease, nervous system & muscles)
Epidermolysis bullosa

8. Types of Mutations: Least Harmful
Nonsense mutation
One base changes, results in early stop (short protein)
Original DNA: ATACGGCATGGGCACTAGG
Original mRNA: UAUGCCGUACCCGUGAUCC
Original AA: M, P, Y, P, Stop
Mutated DNA: ATACGGCATCGGCACTAGG
Mutated mRNA: UAUGCCGUAGCCGUGAUCC
Mutated mRNA: M, P, stop

9. Duchenne Muscular Dystrophy
Hurler Syndrome
(disorder associated with lysosomes)

10. Types of Mutations: Next Harmful
Frameshift mutation
Base is added in or deleted, shifting the reading frame
Many amino acids change, could end protein early or make it extra long
Original DNA: ATACGGCATGGGCACTAGG
Original mRNA: UAUGCCGUACCCGUGAUCC
Original AA: M, P, Y, P, Stop
Mutated DNA: ATACGGCATGTGGCACTAGG
Mutated mRNA: UAUGCCGUACACCGUGAUCC
Mutated AA: M, P, Y, T, V, I

11. Tay Sachs Disease

12. Types of Mutations: Most Harmful
Chromosomal
Large sections of DNA are flipped around, duplicated/copied, removed, etc

13. Charcot Marie Tooth Disease
Jacobsen Disorder

14. Causes of Mutations Spontaneous (Random chance) Mutagens
During DNA replication (copying) when cells divide
During transcription (DNA  mRNA)
Mutagens
External things that increase likelihood of mutations occurring
Radiation
Chemicals (benzene, cyanide, asbestos, etc)

15. Repairing DNA Enzymes proofread DNA and RNA
If enzymes are exposed to mutagens, they are likely to mutate and then won’t do their job correctly.