Mutations

1. Mutations • Hollywood’s images of mutation

2. Severe Combined Immunodeficiency Disorder (SCID) Mutations Ectrodactyly Sickle Cell Anemia Heterochromia iridium Progeria Hypertrichosis

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 - 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 Examples: Down Syndrome Edward’s Syndrome Cri-du-Chat

5. What Causes Mutations? • 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 • Mutations do not have to be bad (evolution)

6. Gene Mutations1. Point Mutations2. Frameshift Mutations

7. Point Mutations Substitution • @A single nucleotide is altered@. Can change one amino acid in a protein • Milk – Mile • GGACAATCA GGACCATCA proline -valine-serineproline-glycine-serine

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

12. Chromosomal Mutations

13. Chromosomal Mutations • Chromosomal mutations involve changes in the number or structure of chromosomes.

14. Chromosomal Mutations • Deletion involves the loss of all or part of a chromosome.

15. Chromosomal Mutations • Duplication produces an extra copy of all or part of a chromosome.

16. Chromosomal Mutations • Inversion reverses the direction of parts of a chromosome.

17. Chromosomal Mutations • Translocation occurs when part of one chromosome breaks off and attaches to another.

18. Harmful and Helpful Mutations • The effects of mutations on genes vary widely. Some have little or no effect; and some produce beneficial variations. Some negatively disrupt gene function. • @However, without mutations, organisms cannot evolve@ • Mutations are the source of genetic variability in a species.

19. Harmful Effects • Some of the most harmful mutations are those that dramatically change protein structure or gene activity causing genetic disorders. • Some cancers, for example, are the product of mutations that cause the uncontrolled growth of cells. • http://www.pbs.org/wgbh/nova/cancer/grow_flash.html

20. Harmful Effects • Sickle cell disease is a disorder associated with changes in the shape of red blood cells. Normal red blood cells are round. Sickle cells appear long and pointed. • @Sickle cell disease is caused by a point mutation in one of the polypeptides found in hemoglobin@. (the blood’s principal oxygen-carrying protein)

21. Beneficial Effects • Mutations often produce proteins with new or altered functions that can be useful to organisms in different or changing environments. • For example, mutations have helped many insects resist chemical pesticides.

22. Beneficial Effects • Plant and animal breeders often make use of “good” mutations. • The condition in which an organism has extra sets of chromosomes is called polyploidy.