Section 10-1 Getting Through Materials move through cells by diffusion. Oxygen and food move into cells, while waste products move out of cells. How does the size of a cell affect how efficiently materials get to all parts of a cell? Work with a partner to complete this activity. 1. On a sheet of paper, make a drawing of a cell that has the following dimensions: 5 cm x 5 cm x 5 cm. Your partner should draw another cell about one half the size of your cell on a separate sheet of paper. 2. Compare your drawings. How much longer do you think it would take to get from the cell membrane to the center of the big cell than from the cell membrane to the center of the smaller cell? 3. What is the advantage of cells being small?

3. Ratio of Surface Area to Volume 4. Cell Division Section Outline Section 10-1 10–1 Cell Growth A. Limits to Cell Growth 1. DNA “Overload” 2. Exchanging Materials 3. Ratio of Surface Area to Volume 4. Cell Division

There are 2 main reasons why cells divide rather than growing larger: Section 10-1 There are 2 main reasons why cells divide rather than growing larger: DNA “Overload”-when a cell is small, the information stored in that DNA meets the needs of the cell; as a cell grows it usually does not make extra copies of DNA which created an information shortage. ex. Small town library

Ratio of Surface Area to Volume- Section 10-1 Material Exchange-all food, water, oxygen and wastes must pass through the cell membrane. The rate at which this exchange takes place depends on the surface area of the cell. Ratio of Surface Area to Volume- Volume increases much more rapidly than the surface area, causing the ratio of surface area to volume to decrease. ex. Main street

Ratio of Surface Area to Volume in Cells Section 10-1 Cell Size Surface Area (length x width x 6) Volume (length x width x height) Ratio of Surface Area to Volume

The process by which a cell divides into 2 new daughter cells. Section 10-1 Division of the Cell The process by which a cell divides into 2 new daughter cells. Before the cell divides, DNA replication takes place. These processes allow the cells to: a. Reduce volume b. Increase surface area to volume ratio c. Maintain available genetic information

Section 10-2 Cell Cycle The cell cycle represents recurring events that take place in the period of time from the beginning of one cell division to the beginning of the next. In addition to cell division, the cell cycle includes periods when the cell is growing and actively producing materials it needs for the next division. 1. Why is the cell cycle called a cycle? 2. Why do you think that it is important for a cell to grow in size during its cell cycle? 3. What might happen to a cell if all events leading up to cell division took place as they should, but the cell did not divide?

C. Events of the Cell Cycle D. Mitosis 1. Prophase 2. Metaphase Section Outline Section 10-2 10–2 Cell Division A. Chromosomes B. The Cell Cycle C. Events of the Cell Cycle D. Mitosis 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase E. Cytokinesis

Video 1

Section 10-2 Chromosomes-are comprised of DNA and protein. These carry the genetic information in eukaryotic cells. Only visible during cell division. Before cell division, each chromosome is replicated, creating identical “sister” chromatids. During cell division each chromatid will go to the 2 new cells.

3. Divides to form 2 daughter cells Section 10-2 Cell Cycle- 1. Cell grows 2. Prepares for division 3. Divides to form 2 daughter cells 4. Daughter cells begin cycle again

Figure 10–4 The Cell Cycle Section 10-2 G1 phase M phase S phase

This phase consists of: G1 phase-main growth of a cell Section 10-2 Interphase This phase consists of: G1 phase-main growth of a cell S phase- DNA replicated G2 phase-many organelles and molecules required for cell division are produced

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Mitosis part of eukaryotic cell division in which the nucleus divides Section 10-2 Mitosis part of eukaryotic cell division in which the nucleus divides Lasts a few minutes to several days. Four phases: 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase

This is the first and longest phase. Events that take place include: Section 10-2 Prophase This is the first and longest phase. Events that take place include: 1. chromosomes become visible 2. centrioles separate and move to opposite sides 3. spindle (fan-like microtubule structure) forms 4. chromosomes attach to spindle fibers

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Second phase of mitosis Events that take place include: Section 10-2 Metaphase Second phase of mitosis Events that take place include: 1. chromosomes line up in the center of the cell 2. microtubules connect the centromere of each chromosome to the two poles of the spindle

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Events that take place include: Section 10-2 Anaphase Third phase of mitosis Events that take place include: 1. the centromeres that join the sister chromatids split allowing the sister chromatids to become individual chromosomes 2. chromosomes move towards the ends of the cell

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Fourth and final phase of mitosis Events that take place include: Section 10-2 Telophase Fourth and final phase of mitosis Events that take place include: 1. chromosomes are at opposite ends of cell and lose shape 2. two new nuclear envelopes will form around the chromosomes

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Section 10-2 Cytokinesis Animal cells-cell membrane is drawn inward until the cytoplasm is pinched into 2 equal parts Plant cells-a cell plate forms midway between the divided nuclei. This eventually becomes a cell membrane and a cell wall.

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Concept Map Cell Cycle Section 10-2 includes M phase (Mitosis) Interphase is divided into is divided into G1 phase S phase Prophase G2 phase Metaphase Telophase Anaphase

Interest Grabber Section 10-3 Knowing When to Stop Suppose you had a paper cut on your finger. Although the cut may have bled and stung a little, after a few days, it will have disappeared, and your finger would be as good as new. 1. How do you think the body repairs an injury, such as a cut on a finger? 2. How long do you think this repair process continues? 3. What do you think causes the cells to stop the repair process?

10–3 Regulating the Cell Cycle A. Controls on Cell Division Section Outline Section 10-3 10–3 Regulating the Cell Cycle A. Controls on Cell Division B. Cell Cycle Regulators 1. Internal Regulators 2. External Regulators C. Uncontrolled Cell Growth

Control of Cell Division Section 10-3

Figure 10–8 Effect of Cyclins Section 10-3 The sample is injected into a second cell in G2 of interphase. A sample of cytoplasm is removed from a cell in mitosis. As a result, the second cell enters mitosis.

Click the image to play the video segment. Animal Cell Cytokinesis Click the image to play the video segment. Video 2

Interest Grabber Answers 1. On a sheet of paper, make a drawing of a cell that has the following dimensions: 5 cm x 5 cm x 5 cm. Your partner should draw another cell about one half the size of your cell on a separate sheet of paper. 2. Compare your drawings. How much longer do you think it would take to get from the cell membrane to the center of the big cell than from the cell membrane to the center of the smaller cell? It would take twice the amount of time. 3. What is the advantage of cells being small? If cells are small, materials can be distributed to all parts of the cell quickly. Section 1 Answers

Interest Grabber Answers 1. Why is the cell cycle called a cycle? It represents recurring events. 2. Why do you think that it is important for a cell to grow in size during its cell cycle? If a cell did not grow in size, each cell division would produce progressively smaller cells. 3. What might happen to a cell if all events leading up to cell division took place as they should, but the cell did not divide? Students may infer that a cell that undergoes all sequences of the cell cycle would grow increasingly larger—to a point at which the cell could no longer exchange materials with the environment efficiently enough to live. Section 2 Answers

Interest Grabber Answers 1. How do you think the body repairs an injury, such as a cut on a finger? The cut is repaired by the production of new cells through cell division. 2. How long do you think this repair process continues? Cell division continues until the cut is repaired. 3. What do you think causes the cells to stop the repair process? Students will likely say that when the cut is filled in, there is no room for more cells to grow. Section 3 Answers

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