10-2 Cell Division

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Copyright Pearson Prentice Hall

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10-2 Cell Division

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In eukaryotes, cell division occurs in two major stages.

The first stage, division of the cell nucleus, is called mitosis.

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Slide 4 of 38 Chromosomes

Chromosomes

Genetic information is passed from one generation to the next on chromosomes.

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Each chromosome

consists of two identical “sister” chromatids.

Each pair of chromatids is attached at an area called the centromere.

Sister chromatids

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When the cell divides, the chromatids separate.

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Slide 7 of 38 The Cell Cycle

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The Cell Cycle

The cell cycle is the series of events that cells go through as they grow and divide.

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During the cell cycle:

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a cell grows

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prepares for division

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The cell cycle consists of four phases:

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G₁ (First Gap Phase)

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S Phase

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G₂ (Second Gap Phase)

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Slide 11 of 38 Events of the Cell Cycle

Events of the Cell Cycle

During G₁, the cell

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increases in size

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During the S phase,

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chromosomes are replicated

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DNA synthesis takes place

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The G₂ Phase (Second Gap Phase)

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organelles and molecules required for cell division are produced

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Cell Cycle

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Slide 15 of 38 Mitosis

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Mitosis

Biologists divide the events of mitosis into four phases:

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Prophase

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Metaphase

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Anaphase

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Mitosis

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Section 10-2

Prophase

Spindle forming

Chromosomes (paired chromatids) Centromere

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Mitosis

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Prophase

Prophase is the first and longest phase of mitosis.

The centrioles

separate and take up positions on opposite sides of the nucleus.

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The centrioles lie in a region called the centrosome.

The centrosome

helps to organize the spindle, a fanlike

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Chromatin

condenses into chromosomes.

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Centriole

Centriole Spindle

Mitosis

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Metaphase

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Metaphase

The second phase of mitosis is metaphase.

The chromosomes line up across the center of the cell.

Microtubules connect the centromere of each chromosome to the

poles of the spindle.

Centriole

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Individual chromosomes

Anaphase

Mitosis

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Anaphase

Anaphase is the third phase of mitosis.

The sister chromatids separate into individual chromosomes.

The chromosomes continue to move until they have separated into two groups.

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Nuclear envelope reforming

Telophase

Mitosis

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Telophase

Telophase is the fourth and final

phase of mitosis.

Chromosomes gather at opposite ends of the cell and lose their distinct

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Slide 29 of 38 Cytokinesis

Cytokinesis

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During cytokinesis, the cytoplasm pinches in half.

Each daughter cell has an identical set of duplicate

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In plants, a structure known as the cell plate forms midway between the divided nuclei.

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The cell plate gradually develops into a separating membrane.

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10-2

The series of events that cells go through as they grow and divide is called

a. the cell cycle. b. mitosis.

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10-2

The phase of mitosis during which the

chromosomes line up across the center of the cell is

a. prophase. b. metaphase.

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10-2

Cytokinesis usually occurs

a. at the same time as telophase.

b. after telophase. c. during interphase.

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10-2

DNA replication takes place during the a. S phase of the cell cycle.

b. G₁ phase of the cell cycle.

c. G₂phase of the cell cycle.

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10-2

During mitosis, “sister” chromatids separate from one another during

a. telophase. b. interphase.

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