Mastering Biology Chapter 9 Homework

DNA replication produces two identical DNA molecules, called ____________, which separate during mitosis.

After chromosomes condense, the _____________ is the region where the identical DNA molecules are most tightly attached to each other

During mitosis, microtubules attach to chromosomes at the ________________.

In dividing cells, most of the cell's growth occurs during ______________

The __________________ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.

During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called ______________.

In most eukaryotes, division of the nucleus is followed by ______________, when the rest of the cell divides.

The _______________ are the organizing centers for microtubules involved in separating chromosomes during mitosis.

The cell cycle represents the coordinated sequence of events in the life of a cell from its formation to its division into two daughter cells. Most of the key events of the cell cycle are restricted to a specific time within the cycle. In this exercise, you will identify when various events occur during the cell cycle. Recall that interphase consists of the G1, S, and G2 subphases, and that the M phase consists of mitosis and cytokinesis. Drag each label to the appropriate target.

Are the sister chromatids present in all or part of this phase?

Is the DNA condensed in all or part of this phase?

Does the cell contain twice as much DNA in this phase as it did in the G1 phase?

What treatment is being compared to the control in the experiment?

The data are plotted in a type of graph called a histogram, which groups values for a numeric variable on the x-axis into intervals. A histogram allows you to see how an entire group of experimental subjects (cells, in this case) are distributed along a continuous variable (amount of fluorescence). In these histograms, the bars are so narrow that the data appear to follow a curve for which you can detect peaks and dips. Each bar represents the number of cells observed to have a fluorescence level in that interval. This in turn indicates the relative amount of DNA in those cells. Which axis indirectly shows the relative amount of DNA per cell? By what relationship?

In the control sample, compare the peaks in the histogram in regions A, B, and C. Which region shows the population of cells with the highest amount of DNA per cell?

Identify which phase of the cell cycle is represented by each region. The regions represent the same cycle phases in both histograms.

In the control sample histogram, does the population of cells in the S phase show a distinct peak? Why or why not?

Now look at the histogram representing the treated sample, which shows the effect of growing the cancer cells alongside human umbilical cord stem cells. In the treated sample histogram, which phase of the cell cycle has the greatest number of cells?

Compare the distribution of cells among G1, S, and G2 phases in the control and treated samples. Which statement best describes the difference(s) in the distribution of cells in the treated sample compared to the control sample?

What does the difference in distribution tell you about the cells in the treated sample?

Which mechanism is the best explanation for how the stem cell-derived inhibitor might arrest the cancer cell cycle at the G1 stage?

Why is it difficult to observe individual chromosomes with a light microscope during interphase?

In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?

Which of these phases encompasses all of the stages of mitosis but no other events?

During __________ both the contents of the nucleus and the cytoplasm are divided.

During ____________ the cell grows and replicates both its organelles and its chromosomes

Which of these is NOT a carcinogen?

__________ is a carcinogen that promotes colon cancer

Which of the following is true of benign tumors but not malignant tumors?

Which of the following ifs found in binary fission but not in mitosis?