1. Mutations

2. Introduction to Mutations

3. When a gene OR chromosome for a particular characteristic changes, it is called a mutation.
A mutation can be defined as any change in the DNA of an organism
Mutations can be random, chance of events or may be caused by a mutagen.
Changes in DNA

4. A mutagen is something in the environment that are capable of causing mutation.
X-rays
UV rays
Certain chemicals
Tobacco smoke
Mutagens can result in the disease known as cancer, which is uncontrolled cell growth
Mutagens

5. Chromosomal mutations
Two types of mutations
Gene mutations
Chromosomal mutations
Occur when a base is added, altered or deleted in the gene sequence resulting in change characteristics
Occur when a chromosome is broken, added or lost during meiosis (production of sex cells)

6. Gene Mutations . There are two categories:
Gene mutations occur when a base is added, altered or deleted in the gene sequence.
. There are two categories:
Point Mutation
Frameshift Mutation
Point mutations  affects a single base in the DNA code. Sometimes has little effect on the gene
Eg: Substitution
Gene Mutations

7. Frameshift mutations  delete or insert bases which effect the entire sequence of amino acids

8. Three types of mutations

9. Normal gene:
CGA TGC ATC
Ala The Stop
Mutated DNA:
CGA TGC TTC
Ala The Lys
What has happened to the sequence?
A nitrogen base is substituted for another.
May or many no affect the amino acid.
Substitution mutations A substitution is a mutation that exchanges one base for another (i.e., a change in a single "chemical letter" such as switching an A to a G).

10. Substitution mutations
Such a substitution could:
Change a codon to one that encodes a different amino acid and cause a small change in the protein produced.
Change a codon to one that encodes the same amino acid and causes no change in the protein produced. These are called silent mutations.
Change an amino-acid-coding codon to a single "stop" codon and cause an incomplete protein. This can have serious effects since the incomplete protein probably won't function.
Substitution mutations

11. Normal Gene:
CGA TGC ATC
Ala The stop
Mutated:
CGA TAG CAT
Ala Iso Val
What has happened to the sequence?
A base is added/inserted to the sequence causing the codons to shift affecting the amino acids and consequently the protein.
In most situations, all of the amino acids change
Insertion mutations Insertions are mutations in which extra base pairs are inserted into a new place in the DNA.

12. Normal gene:
CGA TGC ATC
Ala The stop
Mutated:
CGA TCA TC
Ala Ser
What has happened to the sequence?
A base is removed also causing the codons to shift affecting the amino acid and consequently the protein.
In most situations, all of the amino acids change
Deletion mutations Deletions are mutations in which a section of DNA is lost, or deleted.

13. Chromosomal mutations occur when there is a chromosome broken, added or lost during meiosis (cell division that produces sex cells)
May Involve:
Changing the structure of a chromosome
The loss or gain of part of a chromosome
Chromosome Mutations

14. Four types of Chromosomal Mutations

15. Due to breakage
A piece of a chromosome is lost
Deletion

16. Inversion Chromosome segment breaks off Segment flips around backwards
Segment reattaches
Inversion

17. Occurs when a gene sequence is repeated
Duplication

18. Part of one chromosome is transferred to another chromosome
Translocation

19. Activity Booklet Read the section on Mutations numbered 3-5
Answer Questions on page 5,6,7,8
Activity Booklet