Mutation, DNA Repair, and Cancer PDF

Mutation, DNA Repair, Cancer Chapter Outline: Types of Mutations Causes of Mutations DNA Repair Cancer  Mutations A heritable change in the DNA sequence Essential to evolution Source of variation for natural selection Mutations may be harmfu...

Mutation, DNA Repair, Cancer Chapter Outline: Types of Mutations Causes of Mutations DNA Repair Cancer  Mutations A heritable change in the DNA sequence Essential to evolution Source of variation for natural selection Mutations may be harmful, beneficial or silent  Types of Mutations Base Substitution 5’ – GGCGCTAGATC – 3’ 5’ – GGCGCTGGATC – 3’ Loading… 3’ – CCGCGATCTAG – 5’ 3’ – CCGCGACCTAG – 5’ Frame Shift 5’ – GGCGCTAGATC – 3’ 5’ – GGCAGCTAGATC – 3’ 3’ – CCGCGATCTAG – 5’ 3’ – CCGTCGATCTAG – 5’ Mutations outside of coding sequences A mutation may alter the sequence within a promoter and affect the rate of transcription Loading… May enhance or inhibit transcription Germ-line or somatic cell mutations The time and location of a mutation determines its severity and the heritability Germ-line cells occur in sperm or egg, or in gamete progenitor cells Somatic cells are all other body cells Can occur early or late in development BIOLOGY PRINCIPLE Living Organisms Grow and Develop As a multicellular organism grows and develops, a germ-line mutation is transmitted to all cells of the body, whereas a somatic mutation is found only in a particular region. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Causes of Mutations Mutations may be spontaneous or induced  DNA Repair All living organisms require the ability to detect and repair mutations to minimize damage  Cancer Disease of multicellular organisms Characterized by uncontrolled cell division Cancers originate from a single cell Cell mutates so it grows abnormally Tumor – an overgrowth of cells May remain benign or become malignant  Oncogenes Mutations in genes for cell growth signaling proteins can change them into oncogenes Oncogenes promote cancer by keeping the cell division signaling pathway in a permanent “on” position Loading… Viruses may insert active oncogenes Proto-oncogene Normal gene controlling cell division If mutated, can become an oncogene  Tumor-suppressor genes Inhibitors of cell division Necessary to properly halt cell division otherwise division becomes abnormally accelerated Mutations prevent cell division from stopping when it should