1. Mutations 13.3

2. Mutations Mutation: Any change in the DNA sequence
Can be harmful, helpful, or neither.
2 types: Gene mutations and chromosomal mutations
Point mutation: occurs in a single point in the DNA sequence
Generally occur during replication
Three types: substitution, insertion, and deletion.

3. Point mutations http://www. life. illinois
Substitution
One single base is switched
Usually affects only one amino acid
Sickle cell disease in humans
Insertion and deletion
One base is either inserted or removed
Dramatic changes affecting many amino acids
Also called framshift mutations
May have major effects on protiens

4. Chromosomal Mutation:
Changes in chromosome number or structure
1) INVERSION:
the order of genes on a chromosome is inverted (reversed)
2) TRANSLOCATION:
the movement of a chromosome fragment to a nonhomologus chromosome

5. 3. DELETION
Loss of a all or part of a chromosome
4. DUPLICATION
Duplication of all or part of a chromosome

6. Causes and Effects of Mutations

7. Causes of mutations Errors in replication
1 in 10 million bases is copied incorrectly
This accumulates over time
Mutagens (chemical or physical agents in the environment that cause mutations)
Pesticides, tobacco smoke, environmental pollutants
EM radiation, X-rays, UV light

8. Effects of mutations Cells can sometimes repair damages from mutagens
If not, several possible outcomes:
Base-pairing can be disrupted
DNA strands weaken, which can increase the chances of chromosomal mutations.

9. Helpful or harmful? Some mutations have no effect on the organism.
Some are harmful
Some are helpful
HUGE variation!

10. Harmful mutations
Mutations that dramatically alter the protein structure and gene activity are harmful.
Cancer
Sickle-cell disorder
Other disorders (more on that later)

11. Beneficial Mutations?
May alter an organism to make it more fit for its environment
Insects resisting pesticides
Bacteria mutating to resist antibiotics
Human mutations
Increased bone strength
Viral resistance, such as HIV
Polyploidy
Larger fruits and veggies