Transcript APMeiosis
Meiosis and Life Cycles Self-Incompatibility in Plants A Review of Signal Transduction Meiosis • “halving of cells” • Allows for mixing of genes, sexual reproduction, diversity: -Independent Assortment of Chromosomes -Crossing Over -Random Fertilization Terminology • Haploid, 1N, gamete: • Diploid, 2N, somatic cell: Use the table to answer: -Chromosome # of a frog’s egg. -Chromosome # of a chimp liver -Ask and answer at your table Meiosis Overview and Essential Vocabulary Life Cycles: Group Jigsaw • Dominant Generation (haploid or diploid; gametophyte or sphorophyte) • Stages where the organism is unicellular, multicellular • Organism specific vocab • Seed Plants, Ferns, Mosses, Fungi Meiosis I Meiosis II Meiosis in Human Male • Organ: Testes • Spermatogenesis • Puberty-->Death Meiosis in Human Female • Ovaries • Oogenesis • Puberty-->Menopaus – Meiosis I – Meiosis II Oogenesis: How many complete haploid cell are made? Fertilization • Union of Gametes • Getting into the egg: lysosome in acrosomal process • Signalling Fertilization in Plants • What is pollen? • How could a plant end up being tetraploid? • Identify the chromosome # for: endosperm, embryo, pollen grain, egg Importance of Hormones • In both plants and animals, hormones signal timing of reproduction • Ex: Ethelyne— ripening; Auxin— growth (inhibits reproduction!) • Most plant hormones are gaseous. Why? Organization of Timing • Dormancy – Seeds: • Hormone: Abscicic Acid keeps dormant • Hormone: Giberellic acid stimulates growwth • Cyclic – Flowers: • High ethylene concentrations promote flowering. • What signals might cause hormone changes? • Why might this be advantageous? Organization of Timing Sex Determination Genes on X Chromsome • Necessary for normal development. • Must have an X! • What happens to one of each of the X chromosomes in a human females cell? The Y chromosome • SRY What if you have a defective Y? What if you have an X and no second X or Y? Who determines sex? Gender vs. Sex? • Is sex physically determined? Chromosomally determined? • Are these the same? • How is gender different than sex? Karyotype Amniocentesis • 14-16 week of pregnancy Cost/benefit analysis Are there other ways to determine the sex and health of the fetus? Karyotyping Activity • Summary in lab notebook • Should know some of the chromosomal mutations for the AP test • Arizona biology website http://www.biology.arizona.edu/human_bio/ activities/karyotyping/karyotyping.html Back to Importance of Meiosis • Mendel’s First Law: – Segregation of chromosomes – If this doesn’t work we call it nondysjunction! Nondisjunction--how has meiosis gone out of balance. How could this lead to miscarriage of an embryo ? Mendel’s Law of Segregation Meiosis leads to variation • Mendel’s law of independent assortment • Crossing over • Random Fertilization Question: Why can’t two brothers and sisters (not identical twins) end up exactly the same? Or can they??? Mendel’s Law of Independent Assortment Crossing oVer Random Fertilization • How does random fertilization further increase diversity? • How are self-incompatibility genes important? In small groups: • Compare and contrast mitosis and meiosis. • Use as much vocab as possible. Multiple choice questions use this. • Develop 5 multiple choice questions requiring you to distinguish between these two proceses-you may use an electronic source!