A) Distinguish between the general concept of a gene and the specific concept of an allele at the level of the DNA.

What is the genetic basis and phenotype for each of the following disorders: a) Edwards syndrome b) Patau syndrome c) Klinefelter syndrome d) Down syndrome.

In humans, the recessive allele that causes a form of red-green colour blindness (c) is found on the X chromosome. a.) Determine the genotypes and phenotypes of the F1 generation from a colour-blind father and a mother who is homozygous for normal colour vision. b.) Determine the genotypes and phenotypes of the F1 generation from a father who has normal colour vision and a mother who is heterozygous for colour vision. c.) Draw a Punnett square to determine the genotypes of parents that could produce a daughter who is colour-blind

Two strains of   S. cerevisae (yeast) are crossed. One has the genotype   A B and the other   a b. Which statement correctly describes the tetrads that can be produced by one reciprocal exchange between the   A and   B genes without gene conversion in the dihybrid?             A)   Recombination occurs at the four-strand stage to produce a tetrad with   A B, A B, a B, and   a b chromosomes.                        B)   Recombination occurs at the four-strand stage to produce a tetrad with   A B, A b, a B, and   a b chromosomes.            C)   Recombination occurs at the two-strand stage to produce a tetrad with   A B, A b, a B, and   a b chromosomes.            D)   Recombination occurs at the two-strand stage to produce a tetrad with   A b, A b, a B, and   a B chromosomes.