If there are “CUES” listed within the question, please USE them and UNDERLINE them in your answer!
Chapter 12
1) Paclitaxel is a chemotherapy drug used to treat a variety of cancers. Paclitaxel inhibits both assembly and disassembly of microtubules.
a. Which checkpoint in the cell cycle is affected by Paclitaxel? Explain. (CUES: mitosis, spindle fibers, separation of chromosomes)
b. How does this drug inhibit the growth of cancer?
c. Paclitaxel affects not only cancer cells, but normal cells as well. Would the effects of Paclitaxel be seen first in
skin cells or nerve cells? Justify your reasoning. (CUES: cell division, G0)
2) Use Figure 12.5 to describe the cell cycle. Be sure to briefly describe what happens in all parts of interphase (G1, S, G2) and what happens in all phases of mitosis.
3) Complete the chart below, comparing mitosis and meiosis.
MITOSIS / MEIOSISNumber of daughter cells
Chromosome number of parent cell / ___n / ___n
Chromosome number of daughter cell / ___n / ___n
Number of nuclear divisions
Pairing of homologous chromosomes? (Yes/No)
Daughter nuclei are genetically identical? (Yes/No)
Types of cells that undergo each process
Types of cells produced by each process
4) A slide of dividing cells in an onion root tip is a “snapshot” in time. Each cell is stopped at the particular point in its cell cycle when the slide was made. A biology student examined such a slide under a microscope. Out of 100 cells she caught in the act of dividing, 52 were in prophase, 8 in metaphase, 11 in anaphase, and 29 in telophase. Assuming that the cells are growing and dividing independently, what do these data tell you about the phases of mitosis in onion cells?
5a) Use Figure 12.16 to describe how MPF (Cdk & cyclin) complex acts at G2 to trigger mitosis. (CUES: cyclin accumulation, cyclin-dependent kinase, binding, threshold concentration, cyclin degradation)
5b) The cyclin-CDK complexes regulate the cell cycle by many mechanisms that you’ve learned in previous units. Briefly explain how each mechanism below plays a role in the regulation of the cell cycle.
a. Gene expression b. Protein synthesis c. Signal transduction d. Allosteric activation
6) Compare and contrast the functions of kinetochore microtubules and non-kinetochore microtubules. (CUES: shorten, lengthen, mitosis, sister chromatids, anaphase)
7) Use Figures 12.17 & 12.18 to answer the following: What would happen if you performed the experiment in Figure 12.17 with cancer cells instead of normal cells? (CUES: PDGF, density-dependent inhibition, single layer, clump)
8) The drug cytochalasin B blocks the assembly and function of microfilaments. What would you expect to happen in dividing animal cells treated with this drug? (CUES: cytokinesis, contractile ring, multinucleated, cytoplasm)
Chapter 18
1) Use Figures 18.6 & 18.7 to compare & contrast the lytic & lysogenic cycles of bacteriophages. (CUES: transcription, translation, degradation, lysis, prophage)
2) Use Figure 18.10 to explain how a retrovirus like HIV reproduces. (CUES: provirus, translation, reverse transcriptase, vesicles, capsids, envelope)
3) Describe the 3 ways genetic recombination can occur in bacteria. (CUES: transformation, Griffith, transduction, phage, mating bridge, conjugation)
4) In a rapidly changing environment, which bacterial population would likely be more successful, one that includes individuals capable of conjugation or one that does not? Explain. (CUES: recombinant cell, variation, fitness, natural selection)
5) How can viruses be used to treat some human diseases? What are advantages and disadvantages of this form of treatment as compared to the use of antibiotic therapies? (CUES: bacteriophage, resistance, specificity, mutation)
6) Some mutations can disable genes. What might be the result of such a mutation within the trpR regulatory region of the trp operon? (CUES: repressor protein, transcription, translation, operator, RNA polymerase, tryptophan)
7) Describe the binding of RNA polymerase and repressors to the lac operon when lactose is scarce. What is the effect of this scarcity on the transcription of the lac operon? (CUES: operator, promoter)
8) Use Figure 18.22: Genetic mutations are useful in analyzing the control of gene expression. In the lac operon of E. coli, gene i codes for the repressor protein, Plac is the promoter, o is the operator, and z is the first structural gene. (+) means wild-type; (-) means mutant. Fill in the table below by writing “YES” or “NO” in the box, describing the activation of transcription of gene ‘z’ in different genetic and environmental conditions. Explain your responses.
Z TRANSCRIPTION ACTIVATIONGENOTYPE / LACTOSE PRESENT / LACTOSE ABSENT / EXPLANATION
i+ Plac+ o+ z+ (wild-type) / YES / NO
i- Plac+ o+ z+
i+ Plac+ o+ z-
i+ Plac- o+ z+
i+ Plac+ o- z+
Chapter 21
1. What is a homeotic gene? Why does a mutation in a homeotic gene have a much more drastic effect on the organism than a mutation in other genes? (CUES: body plan, segmentation, protein, activators, repressors)
2. Describe how liver, muscle, and salivary gland cells are specialized for different functions. How do their differences reflect differences in gene expression? Suggest a gene that might be active in each of the cells but none of the others. Suggest a gene that might be active in all the cells. Suggest a gene that is probably not active in any of the cells. (CUES: activator proteins, repressor proteins, regulatory genes, shape, function)
3. Molecular biologists can attach genes to active promoters and insert them into cells. This results in higher than normal expression (overexpression) of the genes. What do you think would happen in each of the following cases if the genes listed would be overexpressed in the specified tissues. Explain your answers.
a. ced-3 in embryonic neuron precursors of C. elegans (Figure 21.18)
b. myoD in undifferentiated myoblasts (Figure 21.10)
4. The control of eye formation during the development of many animals is under the control of a genetic switch involving a transcription factor. Partial DNA sequences for the control gene from two organisms are given below:
Mouse Pax6 gene:
5’-GTA TCC AAC GGT TGT GTG AGT AAA ATT-3’
Fruit fly eyeless gene:
5’-GTA TCA AAT GGA TGT GTG AGC AAA ATT-3’
a. Calculate the percentage of identity (the percentage of bases that are identical) between the two DNA sequences.
b. Use the genetic code (page 314) to determine the amino acid sequences encoded by the two regions and calculate the percentage of identity between the two amino acid sequences.
c. The fruit fly and the mouse diverged from a common ancestor about 500 million years ago. Comment on
your answers to ‘a’ and ‘b’ in terms of the evolution of developmental pathways. What type of mutations in
the gene are present? Why?
5. As you learned in Chapter 12, mitosis gives rise to two daughter cells that are genetically identical to the parent cell. Yet you, the product of many mitotic cell divisions, are not composed of identical cells. Why? (CUES: differentiation, stem cells, differential gene expression, activators)
6. In Figure 47.25 (Chapter 47), the transplanted dorsal lip caused the recipient tissue to become something else it otherwise would not have become. What does this indicate? (CUES: ligand, receptor, transduction pathway, transcription, translation, differentiation, induction)
7. Figure 21.14 shows the importance of morphogen gradients during development. Predict what would happen if researchers injected bicoid mRNA into the anterior end of an egg from a female with a mutation disabling the bicoid gene.