Download 5.1 The Cell Cycle and Mitosis

5.1 The Cell Cycle and Mitosis
Name: ___________________________
1. Outline the three stages of the cell cycle. Summarize each stage in one sentence.
Stage
Summary
Interphase
The cell carries out normal functions and prepares for cell division.
Mitosis
The contents of the cell are separated into two equal parts.
Cytokinesis
The cell is split into two identical daughter cells.
2. List the four stages of mitosis (in order).
1.
Prophase
2.
Metaphase
3.
Anaphase
4.
Telophase
3. Describe the three steps of DNA replication.
1.
An enzyme separates the sides of the DNA.
2.
New bases pair with the bases of the original DNA.
3.
Two new identical DNA molecules are produced.
4. Explain why the following structures disappear in prophase and reappear in telophase.
Structure
Explanation
Nuclear Membrane It disappears so that the DNA can be split in two and moved towards the poles.
Nucleolus
The nucleolus produces ribosomes which are not needed during mitosis.
Science 9 ● Biology● Assignment
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5. Use the illustrations to complete the table.
A
Which diagram shows a cell at the beginning of anaphase?
A
Which diagram shows a cell with sister chromatids moving to the poles of the cell?
D
Which diagram shows a new nuclear membrane forming?
C
B
A
D
List the sequence of the diagrams in the correct order.
6. How is the division of an animal cell different from the division of a plant cell?
In plant cell division, a cell plate forms and turns into a cell wall between the cells. This does not
occur in animal cell division because animal cells do not have a cell wall.
7. In interphase, the DNA is loosely coiled as chromatin. Why is it necessary for the
chromatin to form chromosomes prior to mitosis and cell division?
The DNA must be compact before the nuclear membrane disappears and organized prior to being
divided into two equal/identical parts.
8. Give three possible reasons that the cell cycle might be stopped.
1.
DNA is damaged or has not been replicated.
2.
The cell is short of nutrients.
3.
Spindle fibres do not attach to the chromosomes in metaphase, or the chromosomes have not
moved to the poles in anaphase.
Science 9 ● Biology● Assignment
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9. What might happen if DNA replication and mitosis were not highly controlled?
DNA Replication
Mitosis
If DNA replication was not highly controlled,
many errors would occur and many diseases like
cancer would result. Cells would die or be unable
to divide again.
If mitosis were not highly controlled, some cells
may receive more chromosomes in the daughter
cells while others would receive less. Cells
would die or be unable to divide again.
10. How are cancer cells different from normal cells?
1.
They grow uncontrollably and ignore cell division checkpoints.
2.
They ignore signals from neighbouring cells and grow in multiple layers forming tumours.
3.
They have large abnormal nuclei and do not serve any function in the body.
11. List at least four environmental factors that may lead to cancer.
1.
UV Radiation
2.
X-Rays
3.
Cigarette Smoke
4.
Chemicals
12. Interphase was previously called the resting phase of the cell cycle. Explain why this is
not an accurate name for interphase.
Cells ae carrying out their specific functions during interphase and are not at rest.
Science 9 ● Biology● Assignment
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