1. Mutations

2. Mutations Change in the DNA.
May affect a single gene or an entire chromosome.
May be dominant or recessive.
Somatic mutation
Will NOT be passed to offspring.
Example: cancer
Germ line (sex cell) mutations
Occur in sex cells, mutation may be passed to offspring.

3. Gene Mutations Occur in the individual genes.
Usually occur during replication.
Two types
Point
Frameshift

4. Point (Substitution) Mutation
a single change in one base
Example: Change A to C, G, or T
Only affects
a single
codon. May
or may not
change the
final protein

5. Example: Sickle Cell Anemia

6. Frameshift (Deletion/Insertion)
Base(s) may be inserted or deleted.
Causes abnormal
protein.
Ex:
AATCGC
ACGC (Del)
CGATC
CGGATC (Ins)

7. Chromosomal Mutations
Involve whole or segments of chromosomes.
Usually occur during meiosis (crossing over or anaphase)
4 types
Deletion
Duplication
Inversion
Translocation

8. Deletion
Part of the chromosome is removed.
Ex:

9. Duplication
Part of the chromosome is repeated
Ex:

10. Inversion
The order of the genes in a section of a chromosome is reversed

11. Translocation
Crossing over occurs between non homologous chromosomes.

12. Effects of Mutations Chromosomal mutations affect many genes.
Gene mutations may:
Cause a premature stop codon.
Change sequence of amino acids (changes protein shape).
Silent mutation: mutation that does not affect phenotype.
May not change amino acid sequence. (SEE CHART)
May occur in a non-coding region of the DNA.

13. Nondisjunction
Occurs when chromosomes fail to separate properly during one of the stages of meiosis.
Result is gametes with too many or too few chromosomes.

14. Result of Nondisjunction
Monosomy- missing a chromosome
On a karyotype an entire chromosome will be missing.
Trisomy- having an extra chromosome.
On a karyotype a chromosome is added.