Exam 12: The Cell Cycle

Nucleotides can be radiolabeled before they are incorporated into newly synthesized DNA and, therefore, can be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled 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?

Exposure of zebrafish nuclei to cytosol isolated from eggs at metaphase of mitosis resulted in phosphorylation of NEP55 and L68 proteins by cyclin-dependent kinase 2. NEP55 is a protein of the inner nuclear membrane, and L68 is a protein of the nuclear lamina. What is the most likely role of phosphorylation of these proteins in the process of mitosis?

Certain unicellular eukaryotes, including diatoms and some yeasts, have mechanisms of nuclear division that may resemble intermediate steps in the evolution of mitosis. Which of the following is a characteristic feature of nuclear division in these organisms?

Once a cell enters mitosis, the molecules that activate division must be turned off. What happens to MPF during mitosis?

Movement of the chromosomes during anaphase would be most affected by a drug that prevents which of the following events in mitosis and cell division?

Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?

If there are 40 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis?

FtsZ is a bacterial cytoskeletal protein that forms a contractile ring involved in binary fission. Its function is analogous to ________.

Which of the following properties is associated with a cyclin-dependent kinase (Cdk)?

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely ________.

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

Use the figure to answer the question below. In the figure, G₁ is represented by which numbered part(s)of the cycle?

Use the data in the accompanying table to answer the question. 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?

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

Metaphase is characterized by ________.

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

Which of the following does not occur during mitosis?

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

Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in

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