1. The cell cycle - Mitosis At the beginning of mitosis, the DNA in the cell has already been copied and organized into chromosomes. Mitosis is a division mechanism that separates each of the chromosome copies to ensure that, after cell division, the two new cells have the same number and arrangement of chromosomes as the original cell. There are four main stages of mitosis: prophase, metaphase, anaphase, and telophase. Each stage is defined by the specific events that occur in the cell as it goes through the process of dividing its DNA. The following animation shows the overall pattern of mitosis. Watch the animation completely a couple of times to get a sense of the overall pattern. You may click the play button (box with blue arrow) below the image to play through automatically, or drag the progress button back and forth along the progress bar to move forward and backward in the animation on your own. The illustration below shows a specific stage in mitosis from the animation. 1. Which of the following correctly states what is occurring in this stage? A. Chromosomes are visible, and one of the two centrosomes is starting to migrate to the other pole of the cell. B. Chromosomes have reached the poles of the cell and have started to unravel back into uncondensed strands of DNA. A new nuclear envelope is re-forming around each complete DNA copy. C. Spindle microtubules are starting to pull the chromosomes apart, pulling them toward the poles of the cell. 2. The name of the stage shown and discussed above is? A. Telophase B. Metaphase C. Anaphase D. Prophase 3. When does DNA replication occur? A. DNA replication occurs during the transition to metaphase. B. DNA replication occurs during telophase. C. DNA replication occurs before prophase begins..

1. 1. The cell cycle - Mitosis
At the beginning of mitosis, the DNA in the cell has already been copied and organized into
chromosomes. Mitosis is a division mechanism that separates each of the chromosome copies to
ensure that, after cell division, the two new cells have the same number and arrangement of
chromosomes as the original cell.
There are four main stages of mitosis: prophase, metaphase, anaphase, and telophase. Each
stage is defined by the specific events that occur in the cell as it goes through the process of
dividing its DNA.
The following animation shows the overall pattern of mitosis. Watch the animation completely a
couple of times to get a sense of the overall pattern.
You may click the play button (box with blue arrow) below the image to play through automatically,
or drag the progress button back and forth along the progress bar to move forward and backward
in the animation on your own.
The illustration below shows a specific stage in mitosis from the animation.
1. Which of the following correctly states what is occurring in this stage?
A. Chromosomes are visible, and one of the two centrosomes is starting to migrate to the other
pole of the cell.
B. Chromosomes have reached the poles of the cell and have started to unravel back into
uncondensed strands of DNA. A new nuclear envelope is re-forming around each complete DNA
copy.
C. Spindle microtubules are starting to pull the chromosomes apart, pulling them toward the poles
of the cell.
2. The name of the stage shown and discussed above is?
A. Telophase
B. Metaphase
C. Anaphase
D. Prophase
3. When does DNA replication occur?
A. DNA replication occurs during the transition to metaphase.
B. DNA replication occurs during telophase.
C. DNA replication occurs before prophase begins.