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Unit 2 Lesson 1 Mitosis
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Unit 2 Lesson 1 Mitosis
Splitsville!
Why do cells divide?
• Cell division takes place for different reasons.
• Cell division is important for asexual reproduction,
which involves only one parent organism.
• Most growth in a multicellular organism happens
because cell division produces new cells.
• Cell division also produces cells for repair.
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Unit 2 Lesson 1 Mitosis
What happens to genetic material
during cell division?
• The genetic material in cells is called DNA
(deoxyribonucleic acid).
• In eukaryotic cells, DNA is found in the nucleus.
• A DNA molecule contains the information that
determines the traits that a living thing inherits
and needs to live.
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Unit 2 Lesson 1 Mitosis
What happens to genetic material
during cell division?
• During most of a cell’s life cycle, DNA is found in a
mass of loose strands called chromatin.
• Before cell division, DNA is duplicated.
• As cell division begins, the chromatin is
compacted into visible structures called
chromosomes.
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Unit 2 Lesson 1 Mitosis
What happens to genetic material
during cell division?
• A duplicated chromosome is made of two identical
structures called chromatids.
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Unit 2 Lesson 1 Mitosis
Around and Around
What are the stages of the cell cycle?
• The life cycle of a eukaryotic cell, called the cell
cycle, can be divided into three stages:
interphase, mitosis, and cytokinesis.
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Unit 2 Lesson 1 Mitosis
What are the stages of the cell cycle?
• Interphase is the stage in the cell cycle during
which the cell is not dividing.
• The cell grows to about twice the size it was when
it was first produced. It produces various
organelles and engages in normal life activities.
• Changes that occur during interphase prepare a
cell for division.
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Unit 2 Lesson 1 Mitosis
What are the stages of the cell cycle?
• In eukaryotic cells, mitosis is the part of the cell
cycle during which the nucleus divides.
• Prokaryotes do not undergo mitosis because they
do not have a nucleus.
• Mitosis results in two nuclei that are identical to
the original nucleus.
• When mitosis is complete, the cell has two
identical sets of chromosomes in two separate
nuclei.
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Unit 2 Lesson 1 Mitosis
What are the stages of the cell cycle?
• Cytokinesis is the division of the parent cell’s
cytoplasm.
• Cytokinesis starts during the last step of mitosis
and eventually forms two complete cells.
• In cells that have a cell wall, a cell plate forms
during cytokinesis. The cell plate separates the
cell into two new cells.
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Unit 2 Lesson 1 Mitosis
Phasing Out
What are the phases of mitosis?
• There are four phases of mitosis: prophase,
metaphase, anaphase, and telophase.
• By the end of the four phases, the cell will have
two identical nuclei.
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Unit 2 Lesson 1 Mitosis
What are the phases of mitosis?
• In prophase, the chromatin in the nucleus
condenses into chromosomes. The membrane
around the nucleus breaks down.
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Unit 2 Lesson 1 Mitosis
What are the phases of mitosis?
• In metaphase, the chromosomes line up in the
middle of the cell.
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Unit 2 Lesson 1 Mitosis
What are the phases of mitosis?
• In anaphase, the chromatids of each chromosome
are pulled to opposite sides of the cell.
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Unit 2 Lesson 1 Mitosis
What are the phases of mitosis?
• In telophase, a new nuclear membrane forms
around each group of chromosomes, which
become less condensed.
• Cytokinesis begins during this phase.
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Unit 2 Lesson 1 Mitosis
What are the phases of mitosis?
• After mitosis, cytokinesis results in two new cells,
and the two new cells start the cell cycle again.
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