1. Gene Mutations

2. Mutations only happen to DNA!!!!!!
Gene Mutations
A gene mutation is a change in the nucleotide sequence of a DNA molecule
Some do not change the final protein produced – these are silent mutations
If the final protein is affected, the mutation is said to be expressed (could be negative or positive!)
Mutations only happen to DNA!!!!!!

3. Are mutations always bad?
Mutations create genetic variation in a population.
Favorable mutations give organisms an advantage over others and ensure their survival. These mutations will accumulate in a population.
Less favorable mutations are removed from the gene pool through natural selection.
Organisms with these mutations will not survive.

4. Small Scale Mutations: Gene Mutations
There are three main types of gene mutations:
Point Mutations
Deletions (Frame shift mutations)
Insertions (Frame shift mutations)

5. Point Mutations
In a point mutation, a single nucleotide is substituted for another
Original
Mutation
UCC
CAU
UAU
Serine
Histidine
Tyrosine
UCA
CGU
UAA
Serine
Arginine
STOP
Silent; no change
Expressed; a single amino acid is changed
Expressed; the protein is cut short

6. Examples of Point Mutations
Sickle cell anemia
Lactose intolerance

8. Frameshift mutations

9. Insertions
Insertions occur when one or more new nucleotides are inserted into the DNA sequence.
When this occurs, there is a shift in the reading sequence of DNA during protein synthesis and a completely different protein strand may be formed.

10. Deletions Deletions are when one or more
nucleotides are removed from the
DNA sequence.
As with insertions, this causes a shift in the reading sequence of DNA and can produce a completely different protein strand than the original.
Deletions are irreversible mutations.

11. Frameshift Mutations
In frameshift mutations, the insertion or deletion of a nucleotide changes the entire DNA sequence
Causes a drastic change in the final protein
The fat cat ate the rat
The fat cat aat eth era t
The fat cat tet her at a

12. Tay-Sachs: A frameshift mutation
Tay-sachs is a hereditable disorder which causes paralysis, seizures, loss of hearing and sight, and death (typically before age 5)
1 out of 250 people are a carrier (have one copy of the defective gene)
The mutation is a frameshift causing a lysosome to work incorrectly
Causes brain cells (neurons) to die