1. Gene Mutations
A change in the DNA of a gene is called a mutation. Mutations in gametes can be passed on to offspring of the affected individual, but mutations in body cells affect only the individual in which they occur.

2. Types of Gene Mutations:
1. substitution – one base replaces
another
2. insertion – one or more extra bases
are added
3. deletion – one or more bases are
deleted

3. Gene Mutations
Base Insertion

4. Insertions and deletions are called
frameshift mutations because they
shift the “reading frame” of the
genetic content.
For example:
The fat cat ate the hat.
Insertion: The afa tca tat eth eha t.
The fat cat ate the hat.
Deletion: The fat ata tet heh at.

5. Effects of Mutations
Most mutations have little or no effect, for example, a substitution may affect only a single amino acid and usually has no effect at all.
Insertions and deletions which are frameshift mutations can change every amino acid that follows the point of mutation and therefore can have dramatic effects on the organism.

6. Some mutations produce beneficial variations that allow an organism to better adapt to its environment. Genetic material can be altered by: 1. natural or artificial events 2. environmental conditions 3. errors in replication 4. mutagens – chemical or physical agents in the environment that cause mutations

7. Are mutations always harmful?
No! Some can be beneficial, or have no effect at all.
Mutations that are harmful result in the production of different proteins.
Mutations in gamete cells are passed on to offspring, therefore, they are more significant than a mutation that occurs in a body cell.

8. Write the names of the amino acids that correspond to each mRNA sequence below.
mRNA sequence: AAU-UGG _____________
mutation sequence: AAA-UGG _____________
Which type of mutation occurred?
_______________
Will the mutation affect the organism?
Asp
-Try
Lys
-Try
Substitution
YES

9. Write the names of the amino acids that correspond to each mRNA sequence below.
mRNA sequence: UGU-CCG _____________
mutation sequence: UGU-CCC _____________
Which type of mutation occurred?
_______________
Will the mutation affect the organism?
Cys
-Pro
Cys
-Pro
Substitution NO

10. Write the names of the amino acids that correspond to each mRNA sequence below.
mRNA sequence: GUU-UUG _____________
mutation sequence: GUU-GUU-G ___________
Which type of mutation occurred?
_______________
Will the mutation affect the organism?
Val
-Leu
Val
-Val
Insertion
YES

11. Write the names of the amino acids that correspond to each mRNA sequence below.
mRNA sequence: GGC-UCC _____________
mutation sequence: GGC _____________
Which type of mutation occurred?
_______________
Will the mutation affect the organism?
Gly
-Ser
Gly
Deletion
YES

12. Chromosomal Mutations
deletion – a piece breaks off
2.  duplication – a chromosome fragment
attaches to its homologous chromosome
which then has 2 copies of the gene in the
fragment
3.  inversion – a chromosome piece
reattaches to the chromosome but in
reverse
4. translocation – a piece from another
non-homologous chromosome reattaches

13. Chromosome Mutations