(8) 2. If an organism has a diploid number of 16 in an oocyte,
a) how many tetrads are present in the first meiotic prophase?
b) how many dyads are present in the second meiotic prophase?
c) how many monads migrate to each pole during the second meiotic anaphase?
d) What is the probability that a gamete will contain only paternal chromosomes?
(8) 3. What are the differences between mitosis and meiosis? List 4
differences and indicate which behaviors are mitotic versus meiotic?
(6) 4. How do cell cycle checkpoints contribute to the fidelity of mitosis?
What protein complex is involved in checkpoint control?
(12) 5a. What are Mendel's Four postulates?
5b. What two observations allowed him to state that the inheritance of
traits was particulate and not due to blending?
(12) 6. In sweet peas the seeds can be either round or wrinkled and the seed color can be
either yellow or green, in both cases the latter being the recessive trait. A pea with unknown genotype
and phenotype is test crossed and the offspring progeny looks like:
102 round yellow
96 round green
98 wrinkled green
103 wrinkled yellow
What is the genotype and phenotype of the parents? Are these genes linked or unlinked. If linked how close?
(12) 7. In Drosophila a heterozygous female for the X-linked recessive traits, x,y,z was crossed to a male
that was phenotypically recessive for all traits. The offspring occurred in the following phenotypic ratios:
x y z 473 + + + 458 + y z 38 x + + 32 x + z 12 + y + 8
a) what is the genotypic arrangement of the alleles of these genes on the X chromosome of the female?
Draw both chromosomes.
b) Construct a map of these genes on the X chromosomes (include map distance).
(10) 8. In a plant heterozygous for two gene pairs (Ab/aB) where the two loci are linked and 20
centimorgans apart, two such individuals were crossed together. Assuming that crossing over occurs
during the formation of both male and female gametes, determine the genotype and frequency of the
resulting gametes.
(16) 9. From a Neurospora cross a+ b+ X a b the following frequencies of ordered tetrads were
obtained.
Spore pair 1-2 3-4 5-6 7-8 +,+ +,+ a,b a,b 5013 +,b +,b a,+ a,+ 5093
What can be concluded?
Spore pair
1-2 3-4 5-6 7-8 +,+ +,+ a,b a,b 1766 +,+ a,b +,+ a,b 220 +,+ a,+ +,b a,b 14
What can be concluded?
(12) 10. Pigment in the mouse is only produced when the C allele is present. Individuals of the cc genotype have no color. If color is present it may be determined by the A, a alleles. AA or Aa results in agouti color, while aa results in black coats.
a) What F1 and F2 genotypic and phenotypic ratios are observed from a cross between AACC and aacc mice?
b) In three crosses between agouti females whose genotypes were unknown and males of the aacc genotype, the following phenotypic ratios were observed?
1 8 agouti 8 colorless 2 9 agouti 10 black 3 4 agouti 5 black 10 colorless
What are the genotypes of these female parents?
(10) 11. What are the consequences of a single crossover in the inverted region of a heterzygous cross for:
a) a pericentric inversion
b) a paracentric inversion?
Give your answer in terms of acentrics, dicentrics, duplications and deficiencies and inverted sequences.
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