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

8.7 Mutations Mutations Caused by errors in Replication, transcription, cell division, or by external factors Germ-cell mutation – occurs in a gamete Does 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

8.7 Mutations Lethal Mutations Cause death, often before birth

8.7 Mutations Gene Mutations 1.Point mutation – substitutes, adds or deletes a single nucleotide mutated base

8.7 Mutations Gene Mutations 2. Frame Shift Mutation Deletion & addition point mutation cause the remaining codons to be incorrectly grouped

8.7 Mutations

Chromosome Mutations 1.Deletion – loss of a piece of a chromosome due to chromosomal breakage 2.Inversion – chromosomal segment breaks off and then reattaches in reverse order to the same chromosome –Orig: ATAGCTA –Inv:ATCGATA 3.Translocation – chromosome piece breaks off and reattaches to another non-homologous chromosome

8.7 Mutations

4. Nondisjunction – failure of homologous chromosomes to separate properly during meiosis Two possible outcomes: 1.Trisomy - Three copies of chromosome One gamete has two copies Zygote = 3 copies of chromosome 2. Monosomy - One copy of chromosome One gamete has no copies Zygote - 1 copy of chromosome

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

13.1 Ecologists Study Relationships Pedigree – family record that shows how a trait is inherited over several generations 7.4 Human Genetics and Pedigrees

8.7 Mutations Pedigrees Circles  Girls Squares  Boys Carrier – individual with one copy of a recessive allele Usually do not express the trait but can pass it along to offspring ½ colored in Ex: Autosomal  Hh Sex-linked  X H X h 7.4 Human Genetics and Pedigrees

8.7 Mutations 7.4 Human Genetics and Pedigrees

8.7 Mutations Karyotypes can show changes in chromosomes. –deletion of part of a chromosome or loss of a chromosome –Some translocation changes in chromosomes –extra chromosomes or duplication of part of a chromosome 7.4 Human Genetics and Pedigrees

8.7 Mutations 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 14 th and 16 th week of pregnancy 7.4 Human Genetics and Pedigrees

8.7 Mutations Chorionic villi sampling Physician obtains a sample of the chorionic villi Tissue that grows between the mothers uterus and the placenta, between the 8 th and 10 th week of pregnancy 7.4 Human Genetics and Pedigrees

13.1 Ecologists Study Relationships Cancer Tumor – abnormal group of cells that result from uncontrolled, abnormal cell division 5.3 Regulation of Cell Cycle

8.7 Mutations cancer cell bloodstream normal cell –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 5.3 Regulation of Cell Cycle

8.7 Mutations 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 5.3 Regulation of Cell Cycle

8.7 Mutations 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 5.3 Regulation of Cell Cycle

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

8.7 Mutations 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 5.3 Regulation of Cell Cycle

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

8.7 Mutations How do Cancer cells behave differently from Healthy ones w&list=PLJicmE8fK0Ehrg3meytY7DT8LJiwuU3Th&index =92http:// w&list=PLJicmE8fK0Ehrg3meytY7DT8LJiwuU3Th&index =92

8.7 Mutations 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) 5.3 Regulation of Cell Cycle