Genetics dominant recessive stuff study guide.txt

  1. 2n = 46, how many tetrads are in this cell
    23: a tetrad is a PAIR of chromosomes, and there are 2 sets of each for a total of 46 chromosomes
  2. after 1st round of mitosis and into meiosis at metaphase II, how many chromatids are present from a starting of 2n = 10
    5 chromatids are now present due to the separating of homologous chromosomes during meiosis I
  3. Cell division purpose
    • 1. development from a fertilized cell
    • 2. growth
    • 3. repair
  4. Prior to cell division
    • DNA needs to be replicated
    • Organelles have to be replicated
  5. centromere
    center of chromosome
  6. sister chromatids
    duplicate top or bottom bunny ear looking pairs of genes
  7. cell cycle control proteins
    • 1. cyclins (mostly in M phase)
    • 2. cyclin dependent kinases (CDKs)
    • can combine to MPF allowing to pass into mitosis
  8. Cell control for mitosis in yeast
    • Paul nurse discovered CDC 2, controls G2 --> M phase
    • humans is CDK
  9. external signals & checkpoints for mitosis
    growth factors: proteins stimulate division
  10. Internal signals for growth
    • 1. density dependent inhibition (if dense, will stop growth)
    • 2. anchorage dependency (need something as a base)
    • TUMORS do not follow either of these
  11. Pangenesis
    particles in the blood determine your place (royal blood)
  12. Leeuwenhoek idea
    believed Sperm contained an actual little baby
  13. Blending Theory
    Recognized there was a MIX of 2 parents…like PAINT
  14. Lamarck
    Theory of inheritance of acquired characteristics (ie: giraffe necks)
  15. Mendel
    • studied peas (self fertilizing & pure breeding)
    • cross polinated different plants and looked at traits
    • particulate inheritance: particles are passed down from generations
    • saw the following:
    • NO blending of char.
    • males & females contribute equally
    • Aquired traits NOT inherited (anti Lamarck)
    • each parent contributes
  16. Incomplete Dominance
    • 3:1 -> 1:2:1
    • ie red, pink, white (pheno reflects geno ratio)
  17. Codominance
    • heterozygotes show pheno of BOTH homozygotes
    • ie blood groups AB (except O, which is complete dominance, A or B overpower O, but A does not overpower B)
  18. Lethal Allele
    • 3:1 -> 2:1
    • ie: spina bifida in humans, the dominant allele is deadly (ie: AA = dead)
  19. Pleiotropic
    mutations w/multiple effects
  20. Semilethal
    • Only SOME individuals of a certain genotype die
    • ie: drosophilia which lacks ADH, only die IF encounter alcohol in its lifetime
  21. Epistasis
    • Allele of one gene eliminates the ability to recognize a phenotype from another gene
    • ie either a recessive (aa) does not allow any phenotype to form, doesn't matter what B is for example. Could also be dominant (A_) does not allow phenotype to form, regardless of any other genes.
    • Recessive Epistasis = 9:3:3:1 -> 9:3:4
    • Dominant Epistasis = 9:3:3:1 -> 12:3:1
  22. Complementary Genes
    • 9:3:3:1 -> 9:7
    • REFER to handout
    • mutations in different genes give the same phenotype
  23. Duplicate Genes
    • 9:3:3:1 -> 15:1
    • 2 genes can provide normal fxn, BUT only if BOTH are recessive can a change occur
    • ie chlorophyll can't be made if aabb (so white), otherwise if A_ or B_ will be green
  24. Penetrance
    % of individuals that show the PHENOTYPE associated w/the genotype
  25. Expressivity
    • Degree that a GENOTYPE is exhibited in the phenotype
    • ie mutant which turns things red, the % red = penetrance, but if some are MORE red vs others, this is expressivity
  26. Linkage
    different genes on same chrom do NOT show independent assortment
Card Set
Genetics dominant recessive stuff study guide.txt
genes and alleles