1. 3 mechanisms that contribute to genetic variation
    • -independent assortment of chromosomes
    • -crossing over
    • -random fertilization
  2. 4 related concepts that make up Mendel's Model
    1. Alternative versions of genes account for variations in inherited characters. ex:allele

    2. For each character, an organism inherits two alleles, one from each parent.

    3. If two alleles at a locus differ, then one(the dominant allele) determine's the organism's appearance, and other(the recessive allele) has no noticeable effect on appearance.  ex: F1 plant had purple flowers b/c allele for the trait is DOMINANT

    4. (NOW.K.A. law of segregation) The two alleles for a heritable character separate (segregate)during gamete formation and end up in different gametes... thus egg or sperm get one of two alleles present in organism...this corresponds to distribution of homologous chromosomes to gametes in meiosis 
  3. Multiplication Rule
    • States the probability that two or more independent events will occur together is the product of their individual probabilities.
    • Probability in F1 monohybrid cross can be determined through this.
  4. heterozygous
    having two different alleles for a given gene
  5. homozygous
    having two identical alleles for a gene
  6. gametes
    Haploid reproductive reproductive cell, such as egg and sperm. Unite to make diploid cells.
  7. monohybrid
    Individuals that are heterozygous for one character
  8. monohybrid cross
    Cross between heterozygotes
  9. dihybrids
    Crossing two true-breeding parents differing in two characters produces this. f1 are both heterozygous
  10. dihybrid cross
    • A cross between F1 dihybrids
    •  -can determine whether 2 characters are transmitted to offsrping as a package or independently
  11. addition rule
    states that probability that any one of two or more exclusive events will occur is calculated by adding together their individual probabilities.

    this can be used to figure out probability that an F2 plant from a monohybrid cross will be heterozygous rather than homozygous
  12. complete dominance
    occurs when phenotypes of the heterozygote and dominant homozygote are identical
  13. incomplete dominance
    the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties.
  14. codominance
    two dominant alleles affect the phenotype in separate, distinguishable ways
  15. Four types of alterations of chromosome structures
    • deletion
    • duplication
    • inversion
    • reciprocal translocation
  16. Megan's Choice of Experimental Organism and why...
    Fruit fly

    • Convenient b/c:
    •          -produce many offspring
    •          -generation can be bred in 2 weeks
    •          -have only 4 pairs of chromosomes
  17. Why are X-linked chromosome disorders more common in males than females?
    because females have XX sex chromosomes while males have XY sex chromosomes.
  18. How do you calculate recombination frequencies?
    Total number of recombinants (non-parentals) divided by total number of progeny
  19. Tay-Sachs Disease
    Fatal; dysfunctional enzyme causes an accumulation of lipids in the brain
  20. pleiotropy
    • multiple phenotypic effects
    • -responsible for multiple symptoms of some hereditary diseases like cystic fibrosis and sickle cell disease
Card Set