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Cell Growth & Division Question: Why do cells divide? Cell Growth & Division Question: Why do cells divide?

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Presentation on theme: "Cell Growth & Division Question: Why do cells divide? Cell Growth & Division Question: Why do cells divide?"— Presentation transcript:

1 Cell Growth & Division Question: Why do cells divide? Cell Growth & Division Question: Why do cells divide?

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5 Why do we need to make more cells?Why do we need to make more cells?

6 Q: Who has bigger cells? A: Same cell size, RonRon has MORE!

7 From One Cell to Many Sea Urchin Cell Division

8 Why do we need to make more cells?

9 Why are we one hundred trillion SMALL cells and not one hundred LARGE cells? 100,000,000,000,000 cells because ,000,000,000,000 cells because....

10 They need to be small!

11 I. Why do Cells Divide?

12 A. Cells need to stay small because: / The larger a cell becomes, the more demands on its DNA / Trouble moving enough nutrients and wastes across the cell membrane / Organization! / The larger a cell becomes, the more demands on its DNA / Trouble moving enough nutrients and wastes across the cell membrane / Organization!

13 DNA “Overload” / DNA is the cell’s “library” of information. / Imagine a very large city using one local library for all materials / DNA is the cell’s “library” of information. / Imagine a very large city using one local library for all materials

14 A big bag is weaker, harder to find things Large cell, difficult to maneuver organelles

15 More volume = bigger need The larger the volume of the balloon, the weaker it is. The balloon skin stays the same.

16 B. What is Surface area? The total area of the surface of a three- dimensional object B. What is Surface area? The total area of the surface of a three- dimensional object Large surface area SPEEDS UP the movement of materials What is the surface area of this cube? 24 cm 2 2 cm

17 C. What is Volume? The amount of 3-dimensional space The amount of 3-dimensional space that an object occupies, “capacity” that an object occupies, “capacity” Large volume SLOWS down Large volume SLOWS down movement of materials movement of materials C. What is Volume? The amount of 3-dimensional space The amount of 3-dimensional space that an object occupies, “capacity” that an object occupies, “capacity” Large volume SLOWS down Large volume SLOWS down movement of materials movement of materials What is the VOLUME of the shape here? 200 cm 3 cm

18 D. Ratio of Surface Area to Volume D. Ratio of Surface Area to Volume / As the length of cell increases, volume increases faster surface area (cm 3 compared to cm 2 ) / HIGH ratio desired: quick movement of materials / Ex: 6000/1 is better than 2/1 / As the length of cell increases, volume increases faster surface area (cm 3 compared to cm 2 ) / HIGH ratio desired: quick movement of materials / Ex: 6000/1 is better than 2/1

19 It’s better to have lots of small cells instead of fewer instead of fewer large cells!

20 II. Chromosomes A.All genes located in DNA in nucleus of eukaryotic cell B. Chromosomes are condensed forms of DNA A.All genes located in DNA in nucleus of eukaryotic cell B. Chromosomes are condensed forms of DNA

21 Chromosomes C.Chromosome number is unique to every species Humans: 46 chr. Chimpanzees: 48 chr. Yeast: 32 chr. Adders-Tongue Fern: 1440 chr.!

22 Copied during Interphase Interphase D. After duplication phase, each chromosome consists of two identical “sister” chromatids Anatomy of a Chromosome Chromatids attached at the centromere the centromere

23 II. Cell Division B. Chromosome # stays the same [Cells growths, doubles chromosomes, then splits, forming two daughter cells with original # of chromosomes] B. Chromosome # stays the same [Cells growths, doubles chromosomes, then splits, forming two daughter cells with original # of chromosomes] 46 chromosomes 46 chr A.

24 C. Common Locations for Cell Division / Intestinal lining- every 24 hours / Skin / Blood cells/bone marrow- 120 days / Liver- sometimes / Intestinal lining- every 24 hours / Skin / Blood cells/bone marrow- 120 days / Liver- sometimes

25 D. Cells that Rarely Divide (In G 0 phase ) / Muscle Cells / Cardiac cells / Kidney / Nerve cells / Muscle Cells / Cardiac cells / Kidney / Nerve cells

26 III. Cell Cycle

27 A. Interphase: “I-ball” 90% of the time! 90% of the time! Gap 0 “resting phase”, cell is not growing Gap 0 “resting phase”, cell is not growing Gap 1 cell grows, doubles organelles Gap 1 cell grows, doubles organelles Synthesis duplication of the DNA in Synthesis duplication of the DNA in the cell's chromosomes the cell's chromosomes Gap 2 cell grows, microtubules assembled

28 C. Checkpoints G1 Checkpoint: DNA to be replicated is healthy; cell size G2 Checkpoint: Checks that DNA that was replicated is healthy; rest of cell ready for division M checkpoint: Chromosomes are properly attached to the spindle fibers.

29 What happens if the cell cannot pass through the checkpoint? A)Repair the damage OR B) Self-destruct: APOPTOSIS (Programmed Cell Death) There are proteins in the cell that regulate these processes and determine which way the cell will go.

30 Now entering “M Phase”.. First stop, Mitosis!

31 Prophase- “ pasta ” / Chromatin fibers condense / Nuclear membrane breaks down / Spindle of microtubules forms from centrioles [animals only] / Attach to chromatids on centromere / Chromatin fibers condense / Nuclear membrane breaks down / Spindle of microtubules forms from centrioles [animals only] / Attach to chromatids on centromere

32 Metaphase- “ middle ” / Chromosomes line up in the middle / Spindle fibers attach centrioles to centromeres / Every sister chromatid has fiber attached to it Metaphase- “ middle ” / Chromosomes line up in the middle / Spindle fibers attach centrioles to centromeres / Every sister chromatid has fiber attached to it Centriole Spindle

33 Anaphase: “ away phase ”, form “ A ’ s ” / Spindle fibers contract / Pull sister chromatids apart / The chromosomes continue to move until they are in two groups / Each side has own copy of DNA Anaphase: “ away phase ”, form “ A ’ s ” / Spindle fibers contract / Pull sister chromatids apart / The chromosomes continue to move until they are in two groups / Each side has own copy of DNA Individualchromosomes

34 Telophase- “ end phase ” / Nuclear membranes reform at each pole / Chromosomes unwind / Spindle disappears Telophase- “ end phase ” / Nuclear membranes reform at each pole / Chromosomes unwind / Spindle disappears

35 Last part of “M Phase”.. Cytokinesis!

36 During cytokinesis, the cytoplasm cuts in half

37 Cytokinesis in Plants In plants, a structure known as the CELL PLATE forms midway between the divided nuclei.

38 Cytokinesis in Animals Animal cells contract an actin fiber across middle of cell and “pinch” into 2 new cells- called a “cleavage furrow”. Animal cells contract an actin fiber across middle of cell and “pinch” into 2 new cells- called a “cleavage furrow”.

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41 Twilight STUDIES IT TOO!

42 MITOSIS MITOSIS Video Parent Cell Daughter Cells

43 V. Terms A. Spindle: network of microtubules that move chromosomes during mitosis and meiosis B. Equator: center line of cell where chromosomes line up during metaphase C. Poles: the opposite ends of cell D. Centrioles: animal cells only, move the spindle and chromosomes during division A. Spindle: network of microtubules that move chromosomes during mitosis and meiosis B. Equator: center line of cell where chromosomes line up during metaphase C. Poles: the opposite ends of cell D. Centrioles: animal cells only, move the spindle and chromosomes during division

44 E. Cleavage Furrow: the pinching in of animal cells during cytokinesis F. cell plate: disk in plant cells that divide the cell into two daughter cells during cytokinesis G. Centromere: region where two sister chromatids are joined tightly together E. Cleavage Furrow: the pinching in of animal cells during cytokinesis F. cell plate: disk in plant cells that divide the cell into two daughter cells during cytokinesis G. Centromere: region where two sister chromatids are joined tightly together

45 / “Apoptosis”: programmed cell death

46 VI. Results of Mitosis A. Production of 2 new daughter cells B. Daughter cells are exactly the same as original parent cell C. Cell --> Tissue --> Organ --> Organ System --> Organism A. Production of 2 new daughter cells B. Daughter cells are exactly the same as original parent cell C. Cell --> Tissue --> Organ --> Organ System --> Organism


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