University:
Amherst College
Course:
BIOL 330 | Biochemical Principles of Life at the Molecular Level
Academic year:

2009
Views:

415

Pages:

13
Author:

Jefferson Vega

Chemical Biology 03 Dec 2, 2009 Inheritance I Cell functions •What is the genetic material? •How does it influence all aspects of the cell’s function? •What drives those red arrows? Our genetic instructions consist of ~25,000 genes spread out over 3.2 x 109 DNA nucleotides We inherit one full set from Mom (“maternal”) and one full set from Pop (“paternal”) How is the genetic material passed on so completely from one generation to the next? How is variation introduced? (ie. Why are you not identical to all your siblings, or to either of your parents?) Study of Heredity: how genetic instructions are passed through generations Genetic material packed into convenient packages …Each cell has 46 such packages 1 chromosome Karyotype: 46 “packages” = 23 distinguishable chromosomes 2 of each (1 maternal, 1 paternal): “homologous pair” Chromosomes duplicate (via DNA replication) before every cell division! Identical (=products of DNA replication)! At every cell division (mitosis), all of the genetic material is equally split between the two daughter cells! chromosome replication Regular cell division (mitosis) Produces cells with same number of chromosomes as starting cell! "#$%&!$'()*!+,-./0! Passing of genetic material to next generation through sexual reproduction necessitates generation of special “germ cells” (egg/sperm) that have only half the number of chromosomes Mom passes only half of her genetic material Pop passes only half of his genetic material Regular (“somatic”) cells are DIPLOID (2n) Germ cells are HAPLOID (1n) where n = 23 for humans n = 20 for squirrels n =32 for guinea pigs n= 16 for alligator n= 39 for chicken n = 4 for fruit fly etc.! How is this done precisely? How is this done differently every time?! How is this done precisely? Regular cell division (mitosis) maternal and paternal chromosomes do not interact! Generation of germ cells (meiosis) maternal and paternal chromosomes DO interact! Chromosome Behavior through Meiosis maternal paternal meiosis two homologs of each chromosome; one from each parent homologous chromosomes segregate equally into gametes Follow two chromosome pairs: they act independently (random assortment at the metaphase plate) OR OR OR Because the line up of chromosomes is random, we can talk about probabilities: What are the chances that this egg will receive the large paternal chromosome? What are the chances that this egg will receive both paternal chromosomes? Unique steps for meiosis: what do they accomplish?

Chemical Biology 03 Central Dogma – III and Mutation

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