Chapter 14: Genes in Action Section 1: Mutation and Genetic Change Mutation: Nondisjuction: a failure of homologous chromosomes to separate during meiosis I or the failure of sister chromatids to separate during mitosis or meiosis II Polyploidy: Mutation: I. Mutation: The Basis of Genetic Change A. Mutant B. Genetic differences among organisms originate as some kind of genetic mutation C. Causes of Mutations Enzymes repair some DNA during replication, rarely some is not repaired 3. Rate of mutation can be increased by some environmental factors called mutagens D. Effects of Mutations Many possible effects 1
c. 3. Notice mutation when cause unusual trait or disease 4. II. Several Kinds of Mutations A. Most involve misplacement of nucleotide in DNA segment B. C. Different kinds of mutations are recognized as either changes in DNA or changes in the results of a gene D. Mutations as Changes in DNA During DNA replication wrong nucleotide paired or placed in wrong sequence Point Mutation 3. Insertion or Deletion E. Mutations as Changes in Results of Genes Silent Mutation Typically a point mutation because genetic code is redundant Missense Mutation 2
3. Frameshift Mutation Reading frame of sequence depends on starting point for reading 4. Nonsense Mutation Amino acid sequence may be cut short and protein will fail to function 5. More or Fewer Amino Acids c. F. Chromosomal Mutations In eukaryotic cells, the process of meiosis creates the change of mutations at the chromosomal level Errors can occur during crossover which will cause an unequal exchange of chromosomes or a chromosomal mutation 3. Deletion 4. Duplication Chromosome carries both alleles for each gene in that piece 5. Inversion 3
6. Translocation 7. Gene Rearrangement III. Effects of Genetic Change A. The results of genetic change may be harmful, beneficial or neutral; most changes are neutral and may not be passed on to offspring B. C. Mutations in body cells affect only the individual in which they occur D. Heritable or Not Multicellular Eukaryotes have 2 cell types 3. Any mutation in a somatic cell will be lost when the person dies 4. Mutation in gametes passed to offspring only rarely do mutations cause DRAMATIC changes E. Tumors and Cancer Mutations in these cause normal somatic cells to lose control begin growing and dividing abnormally 4
3. 4. F. New Alleles 3. Most have no effect on the organism 4. A few can change a genes function G. Genetic Disorders Occur because a mutation has altered normal function of a gene 3. III. Large-Scale Genetic Change A. Very large-scale genetic change can occur by misplacement, recombination or multiplication of entire chromosomes B. Recombination During Crossover C. Errors in Sorting Chromosomes Together these genes control cell structure and function 3. 4. Human embryos with missing chromosomes rarely survive 5. Human embryos with extra chromosomes may survive but do not develop normally 5
6. Nondisjunction 7. Polyploidy Largest scale of genetic change when entire genome is duplicated c. Section 3: Genome Interactions Genome: Cell Differentaiation: the process by which a cell becomes specialized for a specific structure or function during multicellular development I. Genomes and the Diversity of Life A. B. See Figure 12 (p. 330-331) C. Comparisons among the genetic systems of many organisms reveal basic biological similarities and relationships II. Moving Beyond Chromosomes A. Genetic Change Antibiotic Resistance B. Multicelluar Development and Aging Gene regulation can happen because of environmental and internal cues 6
C. Cell Differentation Chapter 15: Gene Technologies and Human Applications Genomics: study of entire genomes I. The Human Genome Project A. B. The sequencing of the human genome has advanced the study of human biology yet created new questions. C. Interesting Finds 3. 4. II. Applications of Human Genetics A. B. C. 7