Assignment:Introduction to Genetics
1.A zygote begins with a complement of two homologous chromosome pairs,chromosomes1A and 1B, and chromosomes 2A and 2B.
a.What combinations of these chromosomes would you expect to find in this organism’s somatic cells?What combinations would you expect to find in its gametes?
b.Assume the zygote is heterozygous for three different genes located on the two homologous chromosome pairsdescribed above(CcDdEe), with the genes C and D both found on the same chromosome
(1), and gene E onthe otherchromosome
(2). Both dominant alleles for genes C and D are on the same chromosome of the homologous pair(so in total, we describe this as CD/cd;E/e).
Draw a cell from this organism’s body showing the chromosomes, in the following stages of the cell cycle (be sure all copies of all gene alleles are clearly labeled): G1, G2, Metaphase of Mitosis, and Metaphase of Meiosis.
For this question,assume no crossing over.
2.How many different gamete types are produced by:
a.A heterozygous monohybrid individual?
b.A heterozygous dihybrid individual?
c.An individual of genotype AABb?
d.A heterozygous trihybrid individual?
3.A gardener finds that some of his bean plants have hairy leaves and others have non-hairy leaves. He crosses different plants with these phenotypes and obtains the following results:hairy x non-hairy 56 hairy 61 non-hairyhairy x hairy 63 hairy
0 non-hairynon-hairy x non-hairy
0 hairy 44 non-hairyhairy x hairy 122 hairy 41 non-hairy Offer an explanation to account for these results, using appropriate allele symbols to indicatethe genotypes of the parents and offspring of each cross.
4.In chickens, black colour is due to a dominant allele (E) and red colour to a recessive allele
(e). A crested head is due to a dominant allele
(C) and a plain head to a recessive allele
(c). A red and crested male bird is crossed with a plain black female. They produce many offspring, halfof whichare black and crested, whilehalf are red and crested. Use this information to determine the genotypes of the parents and offspring.Be sure to show your work.
5.In Drosophila, black body colour is due to a recessive allele
(b) and wild-type body colour (grey) to the dominant allele (b+) and sepia eye colour is dueto a recessive allele (s) and wild-type (red) eye colour to a dominant allele (s+). Assume both genes are located on different autosomal chromosomes. Use this information to answer the following questions:
a.If homozygous wild-type females were crossed withmales havingblack body colour and sepia eyes, what genotypes and phenotypes would you expect in the F1 and F2 progeny produced,and in what ratios would you expect these to occur?
b.If homozygous females with black body colour and red eyes were crossed with homozygous males havinggrey body colour and sepia eyes, what genotypes and phenotypes would youexpect in the F1 and F2 progeny produced,and in what ratios would you expect these to occur?
6.If male fruitflies with wild-type phenotypes, but unknown genotypes, are test crossed tofemales with black body colour and sepia eyes, what genotypes, phenotypes and ratios wouldyou expect in the progeny if the wild-type males are:
a.homozygous for both genes
b.heterozygous for both genes
c.homozygous for body colour gene and heterozygous for the eye colour gene
7.In crosses between large and small true breeding gerbils, all F1 progeny are intermediate insize. Among 452 F2 progeny, 106 are large and 108 are small.
Assuming a single gene locus is involved, whatis going on here? For complete marks,include a key forthe allele symbols, and give the genotypes of the parents and offspring.
8.Multiple alleles of the ABO blood-group gene govern the four major blood types in humans(blood types A, B, AB, and O). Alleles IAand IBare co-dominant and allele i is recessive toboth co-dominant alleles.Four babies, two of whom are non-identical twins (produced from different fertilizedeggs),were born in a hospital during the same night. Their blood types were A, B,AB and O.
The three sets of parents had blood types: B and O, A and B, and AB and O.If the twins had blood type A and blood type B, and the other two babies were blood types AB and O, which babies belong to which parents?
9.From your BIOL 1210 materials, you should be able to answer the following essay question (max one page):
in your own words, with diagrams where appropriate, describe the processes of transcription and translation, starting with the genetic code sequence on the chromosome, and ending with the functional protein. Include ALL relevant stepsfor full marks.
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