Chapter 10. Cell Growth and Division

Transcription

1 Chapter 10 Cell Growth and Division

2 Cell Growth A. Limits to Cell Growth 1. Two main reasons why cells divide: a. Demands on DNA as the cell get too large

3 Cell Growth b. Moving nutrients and waste across the cell membrane 2. DNA overload a. The DNA in a small cell is able to meet the cell s needs

4 Cell Growth b. A larger cell does not get information fast enough to survive. 3. Exchanging materials a. Food, oxygen, and water enter and waste exits through the cell membrane.

5 Cell Growth b. The rate at which this happens depends on the surface area of the cell c. The rate at which food and oxygen are used and waste produced depends on the cell s volume

6 Cell Growth 4. Ratio of Surface area to volume a. Surface area of a cube = L x W x # of sides

7 Example #1

8 Example #2

9 Cell Growth b. Volume = L x W x H c. Volume increases faster than surface area

10 Example #1

11 Example #2

12 Surface area to Volume examples

13 Cell Growth B. Division of the cell 1. Cell division process by which a cell divides into two new daughter cells.

14 Cell Growth a. Cell replicates its DNA so each daughter cell gets a copy b. Allows for efficient exchange of materials with the environment.

15 Cell Division A. Cell Division 1. Prokaryotes a. DNA replicates b. Cell separates the contents into two

16 Cell Division 2. Eukaryotes a. Mitosis first stage, division of the cell nucleus b. Cytokinesis second stage, division of cytoplasm

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18 Cell Division B. Chromosomes 1. Chromosomes are copied before the cell can divide 2. Chromatid identical copies of each chromosome a. When the cell divides one chromatid goes to each new cell

19 Cell Division 3. Centromere area where the chromatids are attached.

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21 Cell Division C. The Cell Cycle 1. Interphase period of growth in between the cell dividing.

22 Cell Division 2. Cell cycle series of events that cells go through as they grow and divide. a. Four phases G 1, S, G 2, M

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24 Cell Division D. Events of the Cell Cycle 1. Interphase G 1, S, G 2 a. G 1 Cells do most of their growing, synthesize new proteins and organelles.

25 Cell Division b. S chromosomes are replicated, synthesis of DNA, proteins associated with chromosomes are synthesized.

26 Cell Division c. G 2 Organelles and molecules required for cell division are produced. E. Mitosis prophase, metaphase, anaphase, telophase

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28 Cell Division 1. Prophase 1 st and longest phase of Mitosis a. Chromosomes become visible. b. Centrioles separate and go on opposite sides of the nucleus.

29 Cell Division c. Spindle fanlike microtubule structure that helps separate chromosomes d. Chromosomes attach to spindles.

30 Cell Division e. Plants do not have centrioles f. Nucleolus disappears g. Nuclear membrane breaks down.

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32 Cell Division 2. Metaphase 2 nd phase a. Chromosomes line up down the center of the cell b. Microtubules connect the centromere to the spindles

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34 Cell Division 3. Anaphase 3 rd phase a. Centromere joining the sister chromatids splits b. Chromosomes continue to move until they are separated near the poles of the spindles

35 Cell Division c. Anaphase ends when the chromosomes stop moving.

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37 Cell Division 4. Telophase 4 th phase a. Chromosomes unravel

38 Cell Division b. Nuclear membrane reforms around each cluster of chromosomes c. Spindles break apart d. Nucleolus becomes visible in each daughter nucleus

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40 Cell Division F. Cytokinesis 1. Usually occurs at the same time as telophase 2. Animals a. Cell membrane is drawn inward and pinched off into nearly equal parts.

41 Cell Division b. Each part contains its own nucleus and organelles

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43 3. Plants a. Cell plate forms the nuclei b. Cell plate develops into the cell wall

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45 Regulating the Cell Cycle A. Controls on cell division 1. Cell continue to grow until they come in contact with other cells a. Example: cut in the skin

46 Regulating the Cell Cycle B. Cell Cycle Regulators 1. Cyclin protein that regulates the timing of the cell cycle in eukaryotic cells

47 Regulating the Cell Cycle C. Uncontrolled Cell Growth 1. Cancer disorder in which some of the body s cells lose the ability to control growth

48 Regulating the Cell Cycle a. Cancer cells do not respond to the signals that regulate the growth of most cells b. Divide uncontrollably and form masses of cells called tumors

49 Regulating the Cell Cycle c. Cancer cells may break off and spread through the body 2. Defect in gene p53 a. Normally halts the cell cycle until all chromosomes have been properly replicated