Chapter 10 Cell Growth and Division.pdf
Chapter 10 Cell Growth and Division.pdf
Chapter 10 Cell Growth and Division.pdf
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<strong>Chapter</strong> <strong>10</strong>
<strong>10</strong>.1 <strong>Cell</strong> <strong>Growth</strong><br />
A. Limits to cell Size<br />
1. DNA Overload: with cell growth, no new DNA made<br />
‣Greater dem<strong>and</strong> <strong>Cell</strong> NOT able to provide<br />
2. Exchanging Materials<br />
‣Rate of exchange depends on membrane surface area(SA)<br />
‣Rate of food & O 2 used/waste produce depends on cell<br />
volume (V)
3. Ratio of SA to V<br />
‣Ratio = SA (l x w x # of sides)<br />
V (l x w x h)<br />
‣V INCREASES faster than SA<br />
PROBLEM: lower ratio = cell works harder to get<br />
materials in <strong>and</strong> waste out (traffic jam)
4. <strong>Cell</strong> <strong>Division</strong><br />
‣Before <strong>Division</strong>: cell replicates DNA<br />
‣<strong>Cell</strong> divides into 2 identical daughter cells<br />
‣<strong>Division</strong> reduces cell V = increase SA/V ratio
B. <strong>Cell</strong> division & reproduction<br />
1. Asexual Reproduction<br />
‣ Genetically identical offspring from single parent<br />
‣ Reproduction for single-celled organisms<br />
‣ Method of growth/budding in multicelled organisms
2. Sexual Reproduction<br />
‣ Offspring inherits genetic material from each parent<br />
‣ Offspring formed by fusion of special reproductive<br />
cells
c. Comparing asexual/Sexual Reprod.<br />
Asexual<br />
Sexual<br />
Genetically identical offspring<br />
Genetically diverse offspring<br />
Quick reprod. w/large # of offspring<br />
Diversity advantageous w/envirn.<br />
change
<strong>10</strong>.2 The process of <strong>Cell</strong> <strong>Division</strong><br />
A. Chromosomes:<br />
◦ Bundled packages of DNA carrying cells genetic info
B. Prokaryotic chromosomes<br />
‣ Single circular DNA str<strong>and</strong> in cytoplasm<br />
1. <strong>Cell</strong> Cycle: rapid growth/DNA replication/division<br />
‣<strong>Division</strong> regulated by cell size<br />
‣Binary fission: cell pinches in (two genetically<br />
identical cells)
C. Eukaryotic Chromosomes:<br />
‣ More DNA w/multiple chromosomes (humans=46)<br />
‣ Chromatin: material making up chromosomes (DNA<br />
coiled around proteins called histones)<br />
‣ Nucleosomes: beadlike structure of chromosomes<br />
‣ Condense & become visible during division<br />
‣ Chromosomes ensure precise division of DNA
1. Eukaryote <strong>Cell</strong> Cycle<br />
◦ Stages cell goes thru (grows copies DNA divides)<br />
◦ Includes Interphase (G 1 , S, G 2 ), Mitosis & Cytokinesis
a) Interphase— “in-between”-majority of cell’s life<br />
1) G 1 (Gap 1 ) - cell growth size w/protein/organelles<br />
2) S (Synthesis) - chromosomes replicate, copying DNA<br />
3) G 2 - shortest phase, prep for division
) Mitosis:division of nucleus (quick process)<br />
1) Prophase—P is for poles, packing, & pieces<br />
‣Poles: centrioles to poles-form spindle fibers to sep<br />
chromosomes<br />
‣Packing: DNA condenses-duplicated sister chromatids<br />
attached at centromere become visible<br />
‣Pieces: Nuclear envelope breaks up
2) Metaphase—M for “middle”<br />
‣Centromeres line up across center of cell<br />
‣Spindle fibers connect to dubl chrom centromere
3) Anaphase—A is for apart<br />
‣Centromeres split sister chromatids become<br />
daughter chromosomes
4) Telophase—T is for tidy up<br />
‣Reverses everything in prophase<br />
‣Nuclear Envelope reappears<br />
‣DNA relaxes<br />
‣Spindle breaks apart
c) Cytokinesis: division of cytoplasm<br />
‣Occurs during telophase<br />
‣Plants: cell plate forms between nuclei dividing cells<br />
‣Animals: membrane pinches in until cytoplasm &<br />
organelles equally divided
Mitosis Visual Summary
<strong>10</strong>.3 Regulating <strong>Cell</strong> Cycle<br />
A. Controls on <strong>Cell</strong> <strong>Division</strong><br />
‣Skin, blood, bones cells divide thru out life<br />
‣W/injury: cells divide until contact other cells<br />
1. Cyclins: Proteins that regulating cell cycle<br />
‣Internal regulatory proteins: respond inside events<br />
(wastes build-up; chromo replctn before mitosis)<br />
‣External regulatory proteins: respond outside events<br />
• Ex: <strong>Growth</strong> factors (embryonic dev, wound healing)<br />
‣Apoptosis: programmed cell death (shapes bone,<br />
fingers)
B. Cancer: uncontrolled cell growth<br />
‣<strong>Division</strong> not regulated by cyclins<br />
‣Tumor – mass of cells (benign or malignant-spread)<br />
‣Block nerve connectn, steal nutrients, stop orgn functning<br />
‣Most cancers have defect in gene p53<br />
‣Halts cell cycle till all chromos replicated<br />
‣Damaged p53 cause cells to lose info for normal controls<br />
‣Treatmnt: removal (skin cancer), radiatn, chemothrpy
<strong>10</strong>.4 <strong>Cell</strong> Differentiation<br />
A. Stem cells<br />
‣ Unspecialized cells which become differentiated cells<br />
1. Totipotent stem cells: can develop into any cell type<br />
‣ Fertilized egg/also cells of first few divisions<br />
2. Blastocyst: early hollow ball of cells<br />
‣ Pluripotent cells (inner cells): can become most<br />
cell types (can not become placenta)<br />
‣ Embryonic Stem <strong>Cell</strong>s: are pluripotent-can become<br />
all cells of body
3. Adult Stem <strong>Cell</strong>s<br />
‣ Body contains pool of stem cells (skin, blood)<br />
‣ Are multipotent (more limited)<br />
‣ <strong>Cell</strong>s of an organ/tissue typically become that<br />
organ/tissue
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