Chapter 13
1) How might the genes on the sister chromatids of a certain chromosome compare with each other and with the genes on the sister chromatids of the homologous chromosome? (CUES: allele, locus, traits, identical)
2) Use Figure 13.7 to summarize the major steps in meiosis. Be sure to differentiate between homologous chromosomes and sister chromatids.
3) The somatic cells of a mosquito contain three pairs of chromosomes—two large ones, two medium-sized ones, and two small ones. One large chromosome bears the A allele; its homologue bears the a allele. One medium-sized chromosome bears the B allele; its homologue bears the b allele. One small chromosome bears the C allele; its homologue bears the c allele. Sketch and label mosquito ovary cells at metaphase I of meiosis. Show the different alignments of chromosomes that are possible due to independent assortment.
4) A horticulturalist breeds orchids, trying to obtain a plant with a unique combination of desirable traits. After many years, she finally succeeds. To produce more plants like this one, should she cross-breed it with another plant or clone it? Why? (CUES: sexual reproduction, genetic variation, crossing over, independent assortment)
5) Under what circumstances would crossing over during meiosis NOT contribute to genetic variation among daughter cells? Explain. (CUES: homologous chromosomes, alleles, recombinant chromosomes, parental chromosomes)
6) How do crossing over and independent assortment during meiosis result in daughter nuclei that differ genetically? (CUES: metaphase I, prophase I, recombinant chromosomes, variation, alignment)
Chapter 14
1) In a population of pea plants in a greenhouse, self-pollination can occur. Refer back to Concept 13.1 and explain whether self-pollination is considered asexual or sexual reproduction. Please address your reasoning for why it is one and not the other.
2) Incomplete dominance and epistasis are both terms that define genetic relationships. What is the distinction between these terms?
3) Based on the following pedigree, explain whether the inheritance pattern associated with this disorder is autosomal dominant, autosomal recessive, or X-linked recessive. Explain your identification, and also explain why you eliminated the other two inheritance patterns from consideration. (CUES: carrier, generation, gender)
4) Use Figure 14.7 to describe a testcross and how it is used. (CUES: homozygous dominant, heterozygous, homozygous recessive, genotype, phenotype)
5) Pair each of the four following terms to one of the four descriptions below, and then explain why that pairing demonstrates that term.
a. Epistasisb. Dominance c. Co-dominance d. Incomplete dominance
True-breeding spherical peas bred with true-breeding wrinkled peas produced offspring that were all spherical. (CUES: heterozygous, homozygous, allele)
True-breeding white-flowered snapdragons bred with true-breeding red-flowered snapdragons produced offspring that were all pink-flowered. (CUES: phenotype, genotype)
A man with blood type A and a woman with blood type B produce a daughter with blood type AB. (CUES: genotype, phenotype, multiple alleles, glycoproteins)
A male Labrador retriever dog with a black coat-color and a female Labrador retriever dog with a chocolate coat-color produce a puppy that has a yellow coat color. (CUE: gene expression)
6) Describe the differences in patterns of inheritance between a gene present in the nucleus and a gene present in the mitochondria.
Chapter 15
1) Explain the Inquiry & Experiment in Figure 15.4. Include in your answer an explanation regarding why only the males have white eyes. Is it possible for females to have white eyes? Provide a Punnett square as evidence to support your answer. (CUES: dominant, recessive, sex-linked.)
2) Use Figure 15.5 to explain whether the genes for body color & wing type are on the same or different chromosomes. (CUES: parental phenotype, recombinant phenotype, linked genes.)
3) Consider what you have learned about dominant and recessive alleles in this unit. If a disorder were caused by a dominant X-linked allele, how would the inheritance pattern differ from what we see for the more common recessive X-linked disorders? To help illustrate your answer, include a Punnett square displaying a cross of an affected male with an unaffected female. (CUES: carrier, Barr bodies)
4) Women born with an extra X chromosome (XXX) are generally healthy and indistinguishable in appearance from normal XX women. What is a likely explanation for this finding? When looking at a cell of a female with XXX, what unique feature would you observe? (CUES: X-inactivation, Barr bodies)
5) In a completely hypothetical case, assume that “zany flies” were recently discovered in the International Space Station, and that these flies complete their life cycle in only 90 hours, making them ideal for genetic experimentation. Astronauts decide to run a genetic cross to see if inheritance patterns in space are similar to inheritance patterns on Earth. Analyze the following cross: A true-breeding female with four antennae is mated with a true-breeding male with two antennae. Results are below:
FEMALES / MALESFour antennae / 827 / 904
Two antennae / 0 / 0
Seeking balance, they do the reciprocal cross: A true-breeding female with two antennae is mated with a true-breeding male with four antennae. Results are below:
FEMALES / MALESFour antennae / 757 / 0
Two antennae / 0 / 690
Based on these two crosses, identify the inheritance pattern for this trait. Explain your reasoning. Show Punnett squares for both crosses.
6) Explain the concept of gene linkage. If you performed a test cross with a fruit fly that is heterozygous for two genes, how would you conclude that the two genes are linked? (CUES: crossing over, parental-type offspring, recombinant offspring, chromosome)
7) Use Figure 15.12 to explain non-disjunction.
Chapter 16
1) Explain why, in DNA, T pairs only with A and not with C or G. (CUES: pyrimidine, purine, single-ring, double-ring, double helix, width, hydrogen bonds)
2) E. coli bacteria are used in many genetic studies. Type AE. coli can live on a simple nutrient medium, because they have all the genes necessary to produce the chemicals they need. Type V E. coli can live only on a nutrient medium to which a certain vitamin has been added, because they lack a gene that enables them to make this vitamin for themselves. It has been found that bacteria can absorb genes from other dead, ground-up bacteria. Describe an experiment using type A and type V E. coli to determine whether genes are made of protein or DNA.
3) Use Figure 16.13 to explain what is meant when we say that each DNA strand has directionality. (CUES: 5’, 3’, phosphate group, hydroxyl group, nucleotide, deoxyribose, monomer)
4) Figure 16.16 highlights the “left-hand” replication fork of a replication bubble. Use this figure as a reference to draw the right-hand fork of this replication bubble. Include each of the molecules present in Figure 16.16 and a description of their role in DNA replication. Please remember that DNA is anti-parallel. (CUES: primase, helicase, single-strand binding protein, RNA primer, DNA polymerase, ligase)
5) Use Figure 16.17 to describe how DNA is repaired. (CUES: ligase, nuclease, DNA polymerase, enzymes)
6) Explain how telomeres help prevent the loss of important genetic material. Also, define the function of telomerase, and describe what types of cells are particularly dependent on its continual function. (CUES: repeating sequence, DNA replication, ovary, testes, gametes)