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10.2 The Process of Cell Division
Name:
Biology 5.0
Date:
Period:
Lesson Objectives
 Describe the role of chromosomes in cell division.
 Name the main events of the cell cycle.
 Describe what happens during the four phases of mitosis.
 Describe the process of cytokinesis.
Chromosomes Packages of DNA called chromosomes hold a cell’s genetic information.
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Prokaryotic chromosomes consist of a single, circular strand of DNA.
Eukaryotic chromosomes are highly organized structures.
o The DNA winds around histone proteins, forming chromatin.
o Chromosomes make the precise separation of DNA possible during cell division.
The Cell Cycle The cell cycle is the series of events in the growth and division of a cell.
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In the prokaryotic cell cycle, the cell grows, duplicates its DNA, and divides by pinching in the cell
membrane.
The eukaryotic cell cycle has four stages (the first three of which are referred to as interphase):
o In the G1 phase, the cell grows.
o In the S phase, the cell replicates its DNA.
o In the G2 phase, the cell produces organelles and materials for division.
o In the M phase, the cell divides in two stages—mitosis, the division of the nucleus, and
cytokinesis, the division of the cytoplasm.
Mitosis The division of the nucleus, mitosis, occurs in four stages:
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Prophase: a cell’s genetic material condenses, a spindle starts to form, the nuclear envelope breaks
down.
Metaphase: the duplicated chromosomes line up and spindle fibers connect to the centromeres.
Anaphase: sister chromatids separate and move toward the centrioles.
Telophase: the chromosomes begin to unwind and a nuclear envelope reforms.
Cytokinesis Division of the cytoplasm differs in plant cells and animal cells.
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In animal cells, the cell membrane draws in and pinches off.
In plant cells, a cell plate forms, followed by a new cell membrane, and finally a new cell wall forms.
Chromosomes
For Questions 1–5, complete each statement by writing the correct word or words.
1. Cells carry genetic information in packages of DNA called
2. Most
.
have only one circular strand of DNA.
3. In eukaryotic cells, the genetic structure consists of DNA and a tightly wound protein, which together form
a substance called
.
4. The beadlike structures formed by DNA wrapped around
nucleosomes.
proteins are called
5. _________________________ make possible the precise separation of DNA during cell division.
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The chart below shows key terms from the lesson with their definitions. Complete the chart by writing a
strategy to help you remember the meaning of each term. One has been done for you.
Term
How I’m Going to Remember
the Meaning
Definition
Series of events a cell goes through as it
grows and divides
Area where two sister chromatids are
attached.
One of two identical “sister” parts of a
replicated chromosome
A combination of DNA and protein found in
eukaryotic cells
Made up of DNA; contains the genetic
information needed to make new cells and
carry out cell functions
Part of the eukaryotic cell cycle during
which the cytoplasm divides
Long period of the cell cycle between one
cell division and the next
Inter- means between.
Interphase means between
phases.
Part of the eukaryotic cell cycle during
which the nucleus divides
The Prokaryotic Cell Cycle
The diagram on the left shows how a prokaryotic cell divides. The stages of cell division are shown in order
they happen. Use the flowchart on the right to describe the steps in prokaryotic cell division. In a flowchart,
arrows connect one step to the next. Write the stages in prokaryotic cell division in order in the flowchart.
Cell Division
Flowchart
Cell
membrane
Before division, the DNA forms one circle.
DNA
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Answer the questions.
6. The process of cell division in prokaryotic cells is called
.
7. Will the new cells have the same genetic material as the parent cell, or will each cell have different genetic
material?
8. Is this asexual or sexual reproduction?
9. An example of an organism that reproduces with this kind of reproduction is a
a) salamander.
b) histone.
c) red blood cell.
d) bacterium.
The Cell Cycle
10. What happens during interphase?
11. Complete the cell cycle diagram by writing the correct name of a phase on each line.
a. Color the phase in which most cell
growth occurs blue.
b. Color the phase in which DNA
replication occurs red.
c. Color the phase in which preparation for
mitosis occurs yellow.
d. Color the phase in which mitosis and
cytokinesis occur orange.
12. Which three phases make up interphase?
13. The division of the cell nucleus during the M phase of the cell cycle is called
14. In eukaryotic cells, what happens in the G1 phase that differs from the G2 phase?
15. In eukaryotic cells, what are the two main stages of cell division?
16. Match the process with the correct phase.
S
A. Cells do most of their growing.
G2
B. Chromosomes are replicated, and the synthesis of DNA molecules takes place
G1
C. Many of the organelles and molecules required for cell division are produced.
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Mitosis
Mitosis is the process by which the nucleus of most eukaryotic cells divides. Mitosis has four phases: prophase,
metaphase, anaphase, and telophase.
1. Label the four phases of mitosis in the diagram.
2. Label the spindles and centrioles in one of the phases.
3. Color each chromosome in prophase a different color. Follow each of these chromosomes through
mitosis. Show this by coloring the correct structures in each phase of mitosis.
Chromatin
Chromosome
Interphase
Cytokinesis
Answer the questions.
17. In which phase do the chromosomes line up in the middle of the cell?
18. In which phase do the chromosomes become visible?
19. In which phase do the chromosomes move until they form two groups near the poles of the spindles?
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Mitosis
20. During prophase, when cell chromosomes become visible, what are the duplicated strands of DNA called?
What is the name for the area in which these duplicated strands are joined?
21. What structures are spindle fibers attached to that help pull the paired chromosomes apart?
For the following questions, match the description of the event with the phase of mitosis in which it occurs.
Event
Phase of Mitosis
_________22. The chromosomes separate and begin to move to opposite sides
of the cell.
A. Telophase
_________23. The chromosomes become visible. The centrioles take up
positions on opposite sides of the nucleus.
C. Metaphase
B. Prophase
D. Anaphase
_________24. A nuclear envelope re-forms around each cluster of
chromosomes. The nucleolus becomes visible in each daughter
nucleus.
_________25. The chromosomes line up across the center of the cell.
26. The four circles below represent the nucleus of a cell going through mitosis. Draw four chromosomes as
they go through each phase. Label each phase and describe what is happening to the DNA.
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Cytokinesis
27. What is cytokinesis?
28. Use the Venn diagram to compare and contrast cytokinesis in animal cells with cytokinesis in plant cells.
Cytokinesis
Plant Cell
Both
Animal Cell
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