1. G. Gene Mutations: 1.Mutation- 2. Mutations may be caused by errors in replication or by mutagens. Mutagen- may lead to the production of an abnormal protein. 3. If a mutation occurs __________, it may be transmitted to offspring. a change in the genetic material of a cell. a physical or chemical agent that causes mutations in DNA. in a gamete

2. 4. Types of Gene Mutations: a) Substitution: May or may not alter the amino acid sequence. Example: Normal DNAMutated DNA TAC GCA TGG AAT TAC GTA TGG AAT AUG CGU ACC UUAmRNA: MetArgThrLeu AUG CAU ACC UUA MetThrLeuHis DNA: substitution The replacement of a nucleotide by another one.

4. Example: Insertion Normal DNAMutated DNA TAC GCA TGG AAT TAT CGC ATG GAA T AUG CGU ACC UUAmRNA: MetArgThrLeu AUA GCG UAC CUU A Ile TyrLeuAla DNA: b) Frameshift Mutations: Very dramatic results insertion shift The insertion or deletion of nucleotides in the DNA sequence causing all other nucleotides to shift (this changes the codons).

5. Examples of Genetic Disorders 1.PKU a. Autosomal Recessive b. Lack enzyme needed to metabolize amino acid phenylalanine to tyrosine c. Phenylalanine builds up in body and can cause brain damage d. Detected w/ blood and urine tests e. Treated w/ low phenylalanine diet *Mutations occurred long ago. Alleles are in our gene pool.

6. 2. Sickle-Cell Anemia a. Autosomal Codominant b. Abnormal hemoglobin causes sickle-shaped red blood cells c. RBC’s carry less oxygen and can clog small blood vessels d. Detected w/ a blood test e. Treated w/ folic acid and medications

9. G. Chromosome Disorders Detected by karyotypes

10. G. Chromosomal Disorders 1. Errors in cell division may lead to chromosomal damage or a change in chromosomal number. *drastic effects… often lethal 2. Chromosome damage (structural change): a) Deletion: chromosome fraction breaks off during division b) Duplication: the piece that broke off is added to a homologous chromosome. c) Translocation: the piece that broke off is added to a non-homologous chromosome.

11. a) b) c) A B C D E F G A B C E F G A B C D E F G D Deletion Q R S Duplication Translocation Q R SD A B C D E F GD or

12. Cri Du Chat: deletion on chromosome 5… small head, cat-like cry, mental retardation, facial abnormalities

13. 3. Non-disjunction (change in chromosome number): a) An uneven distribution of chromosomes during cell division (usually meiosis). Meiosis I: homologous pairs don’t separate b) Results in trisomy: 3 copies (instead of 2) of a chromosome Ex: Down Syndrome- individuals with 3 copies of chromosome 21 Meiosis II: sister chromatids don’t separate

16. Ex: Down Syndrome- individuals with 3 copies of chromosome 21 *facial abnormalities, delayed physical, mental, and social development, birth defects

17. Check this out.this

18. Kleinfelters: male w/ extra X chromosome *less muscular body, reduced facial and body hair, possible increase in breast tissue, sterile (infertile)

19. Turner Syndrome: female w/ only 1 X chromosome short stature, swelling of hands and feet, low hairline, low-set ears, webbed necks, sterile (infertile)