1. MUTATIONS

2. Definition = A change in the DNA sequence of an organism that could: have no effect on the organism alter the product of a gene Prevent a gene from functioning properly

3. 1. Type of Mutations a. Germ-cell Mutation A mutation in the DNA of a germ cell that will be transmitted to the offspring by way of the resulting egg or sperm.

4. b. Somatic-cell Mutation A mutation in a body cell that is not heritable.

5. 2. Causes of Mutations = Mutagen Radiation UV light Chemicals Viruses Asbestos

6. 3. Chromosome Mutations A change in the structure of a chromosome (addition or deletion of a section of the chromosome) A change in the number of chromosomes. (due to nondisjunction during meiosis)

7. Chromosome Mutations a.Deletion = Missing regions of a chromosome resulting in the lack of 1 or more genes. Examples = Angelman’s Syndrome and Prader–Willi syndrome both result from the loss of a section of chromosome #15.

8. Chromosome Mutations b. Inversion = A chromosome segment is clipped out, turned upside down and reinserted back into the chromosome.

9. Chromosome Mutations c. Translocation = a fragment of a chromosome is moved ("trans-located") from one chromosome to another - joins a non-homologous chromosome.

10. Chromosome Mutations d. Nondisjuction = the failure of homologous chromosomes or sister chromatids to separate during anaphase I or II of meiosis. Examples: Klinefelter’s Syndrome Patau Syndrome Trisomy X Turner’s Syndrome Edward’s Syndrome

11. 4. Gene Mutations A permanent change in the DNA sequence that makes up a gene.

12. a. Point Mutation - Change, removal, or addition of a single nucleotide (base = letter) in a gene sequence

13. Types of Point Mutations: 1. Substitution = exchange of a single nucleotide for another: A G OR C T (SEE #2 on Worksheet)

14. Types of Point Mutations: 2. Deletion = removal of one or more nucleotides (SEE #3 on Worksheet)

15. Types of Point Mutations: 3. Insertion = addition of one or more nucleotides to the gene sequence. (SEE #4 on Worksheet)

16. Frame shift Mutation: Caused by deletions and/or insertions that causes a change in the grouping of the codons = a change in the reading frame during translation. (SEE #3 and #4 on Worksheet)

17. 5. Others: Silent = change still codes for the same amino acid (SEE #6 on Worksheet) Missense = codes for a different amino acid in the sequence (SEE #’s 2-4 on Worksheet) Nonsense = codes for a “stop” codon before the protein is fully produced. (SEE #5 on Worksheet)