Mutations and Human Genetics

1. KEY CONCEPT Mutations are changes in DNA that may or may not affect phenotype.

2. Mutations Caused by errors in • Replication, transcription, cell division, or by external factors Germ-cell mutation – occurs in a gamete • Do not affect the individual but may be passed on to offspring Somatic mutation – occurs in a body cell • Will affect the individual but are not passed on to offspring

3. Lethal Mutations • Cause death, often before birth

4. mutated base Some mutations affect a single gene • A point mutation - substitutes one nucleotide for another. • Or adds or removes a single nucleotide

5. Frame Shift Mutation • Deletion & addition point mutation - causes the remaining codons to be incorrectly grouped

7. Chromosome Mutations • Deletion – loss of a piece of a chromosome due to chromosomal breakage • Inversion – chromosomal segment breaks off and then reattaches in reverse order to the same chromosome • Translocation – chromosome piece breaks off and reattaches to another non-homologous chromosome

9. Nondisjunction – failure of homologous chromosomes to separate properly during meiosis One gamete would have an extra chromosome • when fertilized would have 3 copies of chromosome • trisomy. One gamete would have one less chromosome • when fertilized would have 1 copy of chromosome • monosomy

10. 7.4 Human Genetics and Pedigrees KEY CONCEPT A combination of methods is used to study human genetics.

11. Pedigree – family record that shows how a trait is inherited over several generations

12. Pedigrees Carrier – individual with one copy of a recessive allele • Usually do not express the trait but can pass it along to offspring

13. 7.4 Human Genetics and Pedigrees A pedigree is a chart for tracing genes in a family. • Phenotypes are used to infer genotypes on a pedigree.

14. 7.4 Human Genetics and Pedigrees • Karyotypes can show changes in chromosomes. • deletion of part of a chromosome or loss of a chromosome • large changes in chromosomes • extra chromosomes or duplication of part of a chromosome

15. Detecting Human Genetic Disorders • Genetic screening – examination of a person’s genetic makeup • Genetic counseling – medical guidance that informs about possible problems that could affect their offspring Prenatal testing • Amniocentesis – removes a small amount of amniotic fluid between the 14th and 16th week of pregnancy

16. Chorionic villi sampling – physician obtains a sample of the chorionic villi – tissue that grows between the mothers uterus and the placenta, between the 8th and 10th week of pregnancy

17. 5.3 Regulation of Cell Cycle KEY CONCEPTCell cycle regulation is necessary for healthy growth.

18. 5.3 Regulation of Cell Cycle Mutations can be caused by several factors. • Replication errors can cause mutations. • Mutagens, such as UV ray and chemicals, can cause mutations. • Some cancer drugs use mutagenic properties to kill cancer cells.

19. 5.3 Regulation of Cell Cycle 8.3 Cancer Tumor – abnormal group of cells that result from uncontrolled, abnormal cell division

20. normal cell cancer cell bloodstream 5.3 Regulation of Cell Cycle • Benign tumors remain clustered and can be removed. • Malignant - uncontrolled dividing cells invade and destroy healthy tissues elsewhere in the body • Metastasize - spread of cancer cells beyond their original site

21. 5.3 Regulation of Cell Cycle Kinds of Cancer – based on types of tissue that affect • Carcinomas – grow in the skin and tissues that line organs. Ex: lung cancer & breast cancer • Sarcomas – grow in bone and muscle tissue • Lymphomas – solid tumors that grow in the tissues that form blood cells • Leukemia – tumors that form in blood-forming tissue – over production of white blood cells

22. 5.3 Regulation of Cell Cycle Causes of Cancer • Carcinogen – substance that increases the risk of developing cancer Ex: tobacco, asbestos, X-rays, or UV rays from sun • Mutagen – cause mutations to occur within a cell that leads to cancer

23. 5.3 Regulation of Cell Cycle • Standard cancer treatments typically kill both cancerous and healthy cells.

24. 5.3 Regulation of Cell Cycle Oncogenes – gene that causes cancer • Proto-oncogene – normal gene that control cell’s growth. When mutated  oncogene • Tumor-suppressor gene – code for proteins to prevent uncontrolled cell division. When mutated  cancer

25. 5.3 Regulation of Cell Cycle Viruses & Cancer • Viruses can stimulate uncontrolled cell division • Cause mutations in proto-oncogenes & tumor suppressor genes

26. 5.3 Regulation of Cell Cycle Cancer Prevention • Diet high in fiber and low in fat • Fruits & vegetables are high in fiber • Vitamins & minerals: carotenoids, vitamins A, C, and E, and calcium • Daily exercise • And lowering exposure to carcinogens (tobacco, UV rays)

27. Extra Credit: • Millions of dollars are spent each year on cancer research. • Contact an oncologist in a cancer treatment center. • Conduct an interview, prepare a paper, and create a visual to show the new treatments that have been developed in the past 10 years