Download Problem Set 6 Solutions for Bis101D: Genetics and Plant Breeding and more Assignments Biology in PDF only on Docsity! Bis101D Key to Problem set 6 (Week 6) 1. Match (numbers with letters) crosses and expected progeny of variegated four o’clock plants: (Hint: Some crosses may yield more than one progeny type. Pollen Ovules Progeny 1. green sector white sector a. green 2. white sector green sector b. white 3. white variegated c. variegated 4. variegated white 2. The flowers of a variegated plant resulting from a chloroplast DNA mutation are allowed to self pollinate. What type of progeny are expected from seeds collected from the following plant sectors?: a. pure white b. pure green c. mixture of white and green (variegated sectors) 3. In the snail Limnaea, shell coiling is determined by the nuclear alleles S (dextral) and s(sinistral), but there is a maternal effect in which progeny phenotype is determined by the genotype of the mother. Selfing of a sinistral snail results in dextral progeny. When these dextral types were selfed, it was found that ¾ of them had dextral progeny and ¼ had sinistral progeny. What is the genotype of the original snail? 4. When crossing two dextral snails, dextral individuals are obtained. Upon selfing one of these F1 snails, it produces only sinistral progeny. What are the genotypes of this F1 snail and its parents? 5. In broccoli male sterility is determined by an interaction of mitochondrial genome and nuclear genes. S cytoplasm together with homozygous recessive nuclear allele ms results in male sterility. S cytoplasm with dominant nuclear allele Ms results in male fertility. Similarly, F cytoplasm with either dominant or recessive nuclear allele results in male fertility. Write the expected progeny genotypes and phenotypes (male fertile or male sterile, including ratios when applicable) for the crosses shown in the table and for their reciprocals. (Assume that that self-pollination does not occur in male fertile plants). Remember, male-sterile plants do not produce fertile pollen, so when used as male parents they will not yield any progeny. 1 female parent male parent progeny of cross progeny of reciprocal Smsms Fmsms Smsms SMsms Smsms SMsMs Fmsms SMsms SMsms FMsms 6. The sex linked recessive allele maroon-like eyes (m) producing light color eyes in Drosophila is due to the lack of the enzyme xanthine dehydrogenase. This enzyme is normally produced by wild type individuals resulting in red color eyes. In heterozygous females for this gene, the enzyme is carried over in their eggs so after fertilization the embryos will be wild type regardless of their genotype. a) In the following cross, give the phenotypes and genotypes of the male and female progeny: m+ m x m Y b) What will be the possible genotypes and phenotypes resulting from backcrossing the resulting F1 females to m males. Why? 7. In the meiotic products of a diploid Neurospora strain of genotype m/+, which of the following linear octads shows occurrence of gene conversion? (m=mutant allele, +=wild type at m locus) a. ++++mmmm b. ++mmmm++ c. +++++mmm d. mm++++mm e. mmmm++++ 8. In the meiotic products of a diploid of Neurospora strain of genotype m/+, which of the following asci reveals the presence of heteroduplex DNA spanning the mutant site, without associated mismatch repair? 2
