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Interest Grabber. 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?

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    1. Interest Grabber 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 taketo 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?

    2. 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

    3. Read paragraph 1, p. 241

    4. Cell Growth Growth in multi-cellular organisms is due mostly to increase in cell numbers, not an increase in cell size. To increase the number of cells, cells need to DIVIDE See p. 246

    5. Two reasons why cells need to divide instead of growing larger: 1. The larger the cell, the more demands are placed on the cell’s DNA. 2. Cells have trouble moving nutrients and wastes across the cell membrane.

    6. DNA “Overload” • In a normal sized cell, DNA is easily able to control cell functions. • When a cell increases in size, more DNA is NOT produced • A large cell would have a hard time functioning with limited DNA

    7. Material Exchange • Food, water, O2, etc. enter a cell through the cell membrane. • Waste products leave the same way.

    8. Material Exchange Therate of exchangedepends on the surface area of the cell. The rate at which food and O2 are used up and waste produced depends on the cell’s volume.

    9. Ratio of Surface Area to Volume An understanding of this ratio is needed to appreciate why cells divide instead of growing larger

    10. Ratio of Surface Area to Volume Imagine that a cell is cubed shape Surface Area = L x W x # of sides Volume = L x W x H Ratio = Surface Area Volume

    11. Ratio of Surface Area to Volume What is the surface area of a cube that has a length of 1cm? Surface Area = L x W x # of sides 1 cm x 1 cm x 6 sides = 6 cm2

    12. Ratio of Surface Area to Volume What is the volume of a cube that has a length of 1cm? Volume = L x W x H 1 cm x 1 cm x 1 cm = 1 cm3

    13. Ratio of Surface Area to Volume Surface Area 6 Volume 1 In other words, there 6 units of surface area to each unit of volume

    14. What if the cell doubles in size? 2 cm x 2 cm x 6 sides = 24 cm2 2 cm x 2 cm x 2 cm = 8 cm3 24 3 8 1

    15. With a 3 : 1 ratio, there are now 3 units of surface area to each unit of volume

    16. What if the cell triples in size? 3 cm x 3 cm x 6 sides = 54 cm2 3 cm x 3 cm x 3 cm = 27 cm3 • 2 • 27 1

    17. With a 2 : 1 ratio, there are now 2 units of surface area to each unit of volume

    18. Ratio of Surface Area to Volume As a cell grows in size, the cell’s volumeincreases more rapidly than the surface area. In other words, the SA : Vol ratio decreases = serious problems for the cell

    19. If the cell becomes too large, it is very difficult for the cell to have necessary products move in and out of the cell

    20. 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

    21. Cell Division During cell division, the cell divides into 2 new cellsbefore the cell becomes too large.

    22. Cell Division During cell division… 1. DNA replicates to assure that each new daughter cell receives genetic information 2. Each daughter cell has an increased SA : Vol ratio to allow the cell to function efficiently

    23. Interest Grabber 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?

    24. Did you mean: mitosis powerpoint Search Results • [PPT] • Mitosis PowerPoint - The Science Spot • File Format: Microsoft Powerpoint - View as HTMLDSQ: Mitosis is the process in which the nucleus divides to form two new nuclei. How does mitosis differ in plants and animals? Mrs. Camp ...sciencespot.net/Media/mitosisPPT.ppt • Did you mean: mitosis powerpoint • Search Results • [PPT] Mitosis PowerPoint - The Science Spot • File Format: Microsoft Powerpoint - View as HTMLDSQ: Mitosis is the process in which the nucleus divides to form two new nuclei. How does mitosis differ in plants and animals? Mrs. Camp ...sciencespot.net/Media/mitosisPPT.ppt

    25. 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

    26. Cell Division Goals: Main events of the cell cycle Four phases of mitosis

    27. Purpose of Cell Division • Asexual reproduction of some organisms • Source of new cells as a multi-cellular organism grows and develops • Source of replacement cells

    28. Cell Division Before a cell divides , it needs to prepare itself to assure that each new daughter cell gets a complete set of information.

    29. Cell Division In eukaryotes, cell division occurs in two stages: Cytokinesis Mitosis Nucleus divides Cytoplasm divides

    30. Chromosomes Made of DNA and proteins Carries the cell’s coded genetic information There is a specific number of chromosomes, depending on the organism

    31. Chromosome Structure Chromosomes are only visible during cell division when they are condensed.

    32. Chromosome Structure Chromosomes are replicated before cell division. After replication, each chromosome now consists of two identical sister chromatids. Why? One chromatid goes to each of the two new cells, and each cell must receive the same genetic information.

    33. Chromosome Structure Each pair of chromatids is attached at an area called the centromere (central part).

    34. The Cell Cycle The cell cycle is a series of events that cells go through as they grow and divide. During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells, each which then begins the cycle again.

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

    36. Figure 10–4 The Cell Cycle Section 10-2 G1 phase M phase S phase G2 phase

    37. Mitosis What is the goal of mitosis? To evenly divide the genetic information that is found in the nucleus.

    38. Cytokinesis What is the goal of cytokinesis? To divide the cytoplasm, which contains the nucleus and other structures, into two equal parts.

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

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

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