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Computer Scientist at the Department of BioSciences, Rice University

Genetics – the basics just before the advanced stuff

Here are a few of my notes about genetics.

Mendelism: Mendel is second on my list of top scientists, just right after Darwin.


  • Gametes: they usually have only one copy of each chromosome (such as sex cells)
  • Zygote: single cell from female gametes and male gametes. “I’ve been using internet before you were a zygote” said Dave Winer, I think.
  • Monohybrid cross: a single trait is studied
  • Dihybrid cross: two traits are studied.
  • Haploid eukaryotic cells have one copy of each chromosome.
  • Diploid eukaryotic cells have two copies of each chromosome.

Worth remembering:

  • In substrate pathways, double mutant shows the upstream gene
  • In signaling pathways, double mutant shows the downstream gene
    • if A suppresses B and A is loss-of-function, then there will be too much B
  • mitosis: duplication into sister chromatids, everything is lined-up in the middle.
  • meiosis I: we have 2 cells, separate homologs, homologs are lined up
  • meiosis II sister chromatids separate
  • recombination: if 100% of tetrads have a crossover, the % of number of progeny showing recombinant types is 50

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