Exam 12: The Cell Cycle

Minutes Spent in Cell Cycle Phases Cell Type Beta 18 24 12 16 Delta 100 1 0 0 Gamma 18 48 14 20 The data in the table were obtained from a study of the length of time spent in each phase of the cell cycle by cells of three eukaryotic organisms designated beta, delta, and gamma. Which of the statements is the best explanation for the difference between time spent in S phase by beta and gamma?

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol prevents microtubule depolymerisation. Thus, Taxol stops mitosis by interfering with which of the following structures or processes?

The mitotic spindle plays a critical role in which of the following processes?

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B?

In the cells of many eukaryotic species, the nuclear envelope has to disappear to permit which of the following events in the cell cycle?

The M phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in ________.

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA?

Nucleotides can be radiolabelled before they are incorporated into newly synthesised DNA and, therefore, can be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labelled T nucleotides and introduced these into a culture of dividing human cells at specific times. Which of the following questions might be answered by using the method described?

At which phase of the cell cycle do centrioles begin to move apart in animal cells?

If the cell whose nuclear material is shown in the figure continues toward completion of mitosis, which of the following events would occur next?

Minutes Spent in Cell Cycle Phases Cell Type Beta 18 24 12 16 Delta 100 1 0 0 Gamma 18 48 14 20 The data in the table were obtained from a study of the length of time spent in each phase of the cell cycle by cells of three eukaryotic organisms designated beta, delta, and gamma. What is the best explanation for the data associated with delta cells?

Starting with a fertilised egg (zygote), a series of six cell divisions would produce an early embryo with how many cells?

Metaphase is characterised by ________.

Density-dependent inhibition is explained by which of the following processes?

Nucleotides can be radiolabelled before they are incorporated into newly forming DNA and, therefore, can be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labelled T nucleotides to study the incorporation of labelled nucleotides into a culture of lymphocytes. They found that the lymphocytes incorporated the labelled nucleotide at a significantly higher level after a pathogen was introduced into the culture. What might they conclude from this observation?

In what way do kinetochore microtubules facilitate the process of splitting the centromeres?

Certain cell types normally have several nuclei per cell. How could such multinucleated cells be explained?

The unlettered circle at the top of the figure shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is grey. The circles labelled A to E show various combinations of these chromosomes. - What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis?

If a cell at metaphase of mitosis contains 20 sister chromatids, how many chromosomes will be present in a G1 cell?