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Phases of Cell Division

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Presentation on theme: "Phases of Cell Division"— Presentation transcript:

1 Phases of Cell Division
Interphase (stage between cell division) Prophase Metaphase Anaphase Telophase By: Ms. Reis

2 Review Each body cell has 2 sets of 23 chromosomes
Therefore a normal human cell has 46 chromosomes

3 Cell Division Cells divide for several reasons:
To repair and heal tissues To exchange materials efficiently with their environment. Food comes in and wastes go out. To send messages to the nucleus efficiently.

4 Mitosis Mitosis is a process of cell division producing two daughter cells from a single parent cell. The daughter cells are identical to one another and to the original parent cell. Note: Parent cell - the cell that divides Daughter cell – the cells that result from cell division

5 Down Syndrome Karyotype photograph of the entire set of chromosomes. 23 pairs for a total of 46 In Down Syndrome-trisomic for chromosome 21, carries an extra chromosome

6 Karyotype A photograph showing the number, shapes and sizes of chromosomes in a cell. All pairs of chromosomes are homologus (identical in size and shape) except the sex chromosomes (23rd pair) One chromosome comes from the father (paternal) one chromosome comes from the mother (maternal


8 The Cell Cycle

9 Interphase The cell prepares for mitosis by growing rapidly
Chromosomes duplicate in the nucleus Longest stage of the cell cycle

10 Chromatin DNA molecules & proteins in a tangled fibrous mass during interphase. Chromatin is composed of 60% protein, 35 % DNA, and 5 % RNA.

11 Centromeres The original chromosome and its duplicate are attached at the centromere. Sister chromatids – the original chromosome and its duplicate while attached at the centromere.

12 Prophase Chromosomes shorten and thicken Nuclear membrane dissolves
Centrioles move to opposite poles of cell in animal cells Formation of spindle fibers The chromatin, diffuse in interphase, condenses into chromosomes. Each chromosome has duplicated and now consists of two sister chromatids.  

13 Metaphase 46 sister chromatids line up at the equatorial plate.

14 Anaphase Spindle fibers pull sister chromatids (duplicated chromosomes) apart to the opposite end of the cell. Centromeres divide.

15 Telophase Cell begins to pinch in two
New nuclear membrane starts to form Cytokinesis -division of the cytoplasm and organelles between both daughter cells

16 Conclusion Each new cell ends up with the same amount of genetic material as the original cell. Both daughter cells are identical to the parent cells.

17 Cytokinesis In animal cells the cell membrane pinches inward at the equator of the cell, producing a furrow. In plant cells a cell plate is formed across the equator of the cell. Cellulose is added to the cell plate to form a new cell wall.

18 Discussion Question How many chromosomes would you expect to find in each daughter cell after mitosis? Predict what might happen to each daughter cell if all the chromosomes moved to only one side of the cell during anaphase. Why is it necessary to duplicate the nuclear material?

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