First 2 billion years Advantages: One parent (quick and easy) Increase numbers quickly Favorable in stable environment Disadvantages: Offspring identical (clones) Slow evolution/ less diversity (extinction) Division into two or more Equal= binary Can be along any plane Group of cells on parent develops into new individualGroup of cells on parent develops into new individual Frag men ta tion Body parts regenerate Virgin birth Egg develops without fertilization- some diploid/ some haploid Uncommon- role in social organisms Gametes produced (sperm and ova) Advantages: Genetic diversity (withstand environmental pressure) Disadvantages: Complicated-- time, energy requirement Cost of meiosis-- only half genes passed Wastage in the production of males Somatic cell Gamete or Germ cell Necessary for ANY cell to divide: reproductive signal replication of DNA segregation of DNA cytokinesis of cytoplasm Nucleoid region (protein scaffold) (p) (q) 53 rule: always copies 5-3 link 1 interphase 2 interphase 3 early prophase 4 mid prophase5 late prophase6 metaphase 7 early anaphase8 anaphase9 early telophase 10 late telophase (cytokinesis) link animation Down's Syndrome: 47 chromosomes with 3 #21 chromosomes. Triple-X Syndrome: 47 chromosomes caused by 3 X chromosomes. Klinefelter's Syndrome: 47 chromosomes caused by 2 X chromosomes and 1 Y chromosomes. Turner's Syndrome: 45 chromosomes with 1 X chromosome (caused by the absence of one of the X chromosomes or a Y chromosome). Leads to aneuploidy Too much mitosis or too little apoptosis All cancers are of genetic origin Germ line- Mendelian inherited- (single gene)- 5-10% Non-inherited- somatic mutations Familial- inherited Increase of susceptibility Multifactorial- many genes Environment Other genes (repair) 1.Go Mutation (1) Proto OncogenesOncogenes 2. Stop Mutation (2) Suppressor mutantSuppressor genes suppressor 3. Genes that recognize DNA errors and repair or halt cell cycle (apoptosis) Repair Mutation (3) Genes abnormal repair genes Normal Genes Mutation Cancer Genes Examples of cancer genes APC SuppressorColon P 53 Supressor Various 1994 P16 Suppressor Melanoma 1995 HNPCC Repair Colon AT RepairVarious 1996 HPC1 OncogeneProstate BRCA1-2 SuppressorBreast 1997 B-CAT OncogeneColon PTEN SuppressorBrain Breast Colon 1998 P73 SuppressorNerve link hhmi 2004- Question 1 Meiosis reduces chromosome number and rearranges genetic information. (a) Explain how the reduction and rearrangement are accomplished in meiosis. (b) Several human disorders occur as a result of defects in the meiotic process. Identify one such chromosomal abnormality; what effects does it have on the phenotype of people with the disorder? Describe how this abnormality could result from a defect in meiosis. (c) Production of offspring by parthenogenesis or cloning bypasses the typical meiotic process. Describe either parthenogenesis or cloning and compare the genomes of the offspring with those of the parents. Turner Klinefelter Down