Understanding Stages of Mitosis

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Biology › Understanding Stages of Mitosis

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1

A cell is arrested during mitosis. At this stage, distinct chromatids are visible at opposite poles of the cell. Which stage of mitosis does this describe?

Anaphase

Metaphase

Prophase

Telophase

Explanation

The phases of mitosis can be described as follows:

During prophase chromatin condenses to form discrete chromosomes.

During metaphase microtubules attach to the kinetochores and chromatids begin segregating.

During anaphase sister chromatids have been separated and reside at opposite poles of the cell.

During telophase both sets of chromatids are surround by new nuclear membranes and chromosomes decondense into chromatin.

Cytokinesis (the dividing of the cytoplasm into two cells) follows telophase.

If the cell were arrested during telophase, distinct chromatids would no longer be visible.

2

What is the difference in chromosome number, in each daughter cell, between mitosis and meiosis?

Mitosis ends with two diploid cells and meiosis ends with 4 haploid cells.

Meiosis ends in a dipliod cell and mitosis ends with a haploid cell.

Both mitosis and meiosis process end with two haploid cells.

Both mitosis and meiosis end with two diploid cells.

Mitosis ends in a diploid cell and meiosis ends in a haploid cell.

Explanation

Mitosis has only one round of chromosome separation and creates all cells, other than sex cells. For example skin cells. This process ends with two diploid cells that are genetically identical to the parent cell.

Meiosis is the process that generates the cells that occur in sexual reproduction cells, otherwise known as gametes. This process, since it has two rounds of chromosome separation, will end with 4 haploid cells, or half the genetic information of the parent cell.

3

Please name the first stage of mitosis and two things that occurs during this phase.

Prophase; the mitotic spindle forms and chromosomes become more pronounced.

Telophase; chromosomes line up on the spindle.

Prophase; chromosomes line up on the spindle.

Metaphase; the spindle is fully formed.

Metaphase; the nuclear envelope breaks down.

Explanation

Prophase is the first stage of mitosis. The cell cytoplasm and nucleus undergo several changes. At this point the mitotic spindle is forming but the nucleus is still intact. In this phase the chromosomes become tightly packed and the nucleoli disappear. Each chromosome is paired with its sister chromatid joined in the middle at the centromere.

Prophase

4

What is the correct sequence of the stages of the M phase of the cell cycle?

Prophase, metaphase, anaphase, telophase

Prophase, anaphase, metaphase, telophase

Metaphase, prophase, anaphase, telophase

Telophase, anaphase, metaphase, prophase

Explanation

The mitosis (M) phase of the cell cycle has four sequential stages: prophase, metaphase, anaphase, and telophase. In the first stage, prophase, each chromosome becomes condensed and more visible, and there is the breakdown of the nuclear membrane and appearance of spindle fibers. In the next phase, metaphase, the chromosomes line up along the metaphasic plate. The spindle fibers are completely formed and are attached to each sister chromatid of the chromosomes. Next, during anaphase, the centromeres holding the sister chromatids together are divided and the sister chromatids are pulled apart by the spindle fibers to opposite poles of the diving cell. During the last phase of mitosis, telophase, the two sets of chromosomes reach the poles of the cell. This is followed by the reformation of the nuclear envelope, uncoiling of the DNA, and disappearance of the spindle fibers.

5

Prophase

In what phase of mitosis is the cell shown?

Prophase

Anaphase

Telophase

Cytokinesis

Metaphase

Explanation

The cell pictured above is in prophase. Key indicators that the cell is in this stage are that the nuclear envelope is still intact and chromosomes have become condensed and paired up with sister chromatids.

6

The division of centromeres occurs during which phase of mitosis?

Anaphase

Metaphase

Prophase

Telophase

Cytokinesis

Explanation

Centromeres are the structures at the center of each chromosome that hold the sister chomatids together. The division of the centromeres occurs during anaphase. This allows for the separation of each sister chromatid into its respective daughter cell.

Mitosis has four sequential stages: prophase, metaphase, anaphase, and telophase. In prophase, each chromosome becomes condensed and more visible, and there is the breakdown of the nuclear membrane and appearance of spindle fibers. In the next phase, metaphase, the chromosomes line up along the metaphasic plate. The spindle fibers are completely formed and are attached to each sister chromatid of the chromosomes. Next, during anaphase, the centromeres holding the sister chromatids together are divided and the sister chromatids are pulled apart by the spindle fibers to opposite poles of the diving cell. During the last phase of mitosis, telophase, the two sets of chromosomes reach the opposite poles of the cell. This is followed by the reformation of the nuclear envelope, uncoiling of the DNA, and disappearance of the spindle fibers. After the M phase is the separation of the cytoplasm, known as cytokinesis, which results in two distinct daughter cells.

7

Premetaphase

In what stage of mitosis is the cell shown in?

Prometaphase

Anophase

Telophase

Metaphase

Prophase

Explanation

The cell in the picture about is in the prometphase stage. Key indicators of this phase are the breakdown of the nuclear envelope around the genetic material and the spindle beginning to interact with the chromosomes.

8

In which stage of mitosis do sister chromatids line up along an imaginary line that divides the cell in half?

Metaphase

G2

S phase

Anaphase

Cytokinesis

Explanation

Metaphase is characterized by the lining up of chromosomes along the "metaphase plate," an imaginary line that divides the cell in half. Following metaphase and during anaphase, the sister chromatids will separate and move towards the poles of the cell.

9

In what stage of Mitosis does crossing over occur?

Crossing over does not occur in mitosis.

Crossing over occurs in metaphase when all the chromosomes are aligned in the middle of the cell. Their close proximity allows crossing over to occur.

Crossing over occurs in anaphase at each pole of the cell where the chromosomes are packed together.

Crossing over occurs in telophase right before the cells split since all the DNA and cell growth has occurred by this point.

None of these

Explanation

Mitosis is cellular cloning. This means that Mitosis ends with two identical cells; no variation. Mitosis is how the body repairs skin and other tissues. Because the tissue being repaired needs to match its neighboring cell, there is no need for variation which is exactly what crossing over does. It mixes-n-matches the genetic material amongst chromosomes, which helps to give rise to the variation we see amongst our own species and in all animals that reproduce sexually (Meiosis).

10

Metaphase

What phase is the cell above currently in? How can you tell?

Metaphase; you can tell because the chromosomes are neatly lined up in the center of the cell on the mitotic spindle.

Prophase; you can tell because of the cell's shape.

Telophase; you can tell because there is no nuclear envelope anymore.

Anaphase; you can tell because the chromosomes are neatly lined up in the center of the cell on the mitotic spindle.

Prometaphase; you can tell because there is no nuclear envelope anymore.

Explanation

The condensed chromosomes are aligned on the metaphase plate (an imaginary line in the middle of the cell). They align this way because of the microtubules that are pulling them to the opposite sides.

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