1. Mutations
Hollywood’s images of
mutation

2. Mutations
Actual Mutations
in fruit flies

3. What is a mutation? A mutation is any change in a cell’s DNA
A mutation can occur in an individual gene
- results in a single changed protein
- cystic fibrosis a mutation in the protein that makes a type of ion channels in cell membrane
- bacterial resistance to antibiotics is an example of a beneficial gene mutation

4. What is a mutation continued
A mutation can occur in a chromosome
- a chromosome contains many genes
- chromosomal mutations affect many
proteins
If a mutation occurs in a sex cell, the mutation will be passed to offspring
Examples: Down Syndrome
Edward’s Syndrome
Cri-du-Chat

5. What Causes Mutations?
Environment: Can be caused by mutagens- a physical or chemical cause of mutation. Examples: UV light, radiation, drugs, and benzene.
Mutagens are often also carcinogens – anything that causes cancer
Can be natural, random events.
- mutations occur in 1/100,000 DNA replications (DNA mistakes)
Mutations do not have to be bad (evolution)

6. Gene Mutations

7. Point Mutations
A single nucleotide is altered. Can change one amino acid in a protein
Milk – Mile
GGACAATCA GGACCATCA
proline -valine-serine proline-glycine-serine
***ONLY ONE AMINO ACID IS AFFECTED AS A RESULT OF POINT MUTATIONS!***

8. Frameshift Mutations
A nucleotide is either inserted or deleted from a gene.
-all of the triplets from the point of mutation onward will be changed

9. Frameshift Mutations Insertion
An insertion occurs when a nucleotide is added to a gene
Example: A nucleotide is inserted
The fat cat ate the rat
The faa tca tat eth era t
-the extra nucleotide shifts all of the triplets that follow

10. Frameshift Mutations Deletions
A deletion occurs when a nucleotide is removed from a gene.
Example: A nucleotide is removed
The fat cat ate the rat
Thf atc ata tet her at

11. proline -valine-serine arginine-cysteine-stop Deletion
Insertion
GGACAATCA GCGACAATCA
proline -valine-serine arginine-cysteine-stop
Deletion
GGACAATCA GGAAATCA
proline -valine-serine proline-leucine

12. Deletion Example: Cri du chat syndrome
Due to a deletion of part of the short arm of chromosome 5
Occurrence: 1/50,000 births
Crying babies sound like cats; mental disability Death by about 4 years

13. Chromosome Mutations

14. KARYOTYPES Kary = nucleus
Karyotype = chart of metaphase chromosome pairs arranged according to length and location of the centromere
Used to pinpoint unusual chromosome numbers in cells

16. Nondisjunction
Sometimes during meiosis, the homologous chromosomes fail to separate properly
This can result in two types of chromosomal mutations:
(1) trisomy (have an extra set of chromosomes)
(2) monosomy (missing one set of chromosomes)

17. XYY Syndrome

18. Turner’s Syndrome

19. Down’s Syndrome

20. Klinefelter syndrome: 47, XXY males, sterile, feminine body characteristics. Normal intelligence.

21. Edward’s syndrome (trisomy 18):occurs in 1:6000 or 1:8000 live births; very few survive birth.