Chapter 10 Cell Growth and Division.pdf

Chapter 10

3. Ratio of SA to V‣Ratio = SA (l x w x # of sides)V (l x w x h)‣V INCREASES faster than SAPROBLEM: lower ratio = cell works harder to getmaterials in and waste out (traffic jam)

4. Cell Division‣Before Division: cell replicates DNA‣Cell divides into 2 identical daughter cells‣Division reduces cell V = increase SA/V ratio

B. Cell division & reproduction1. Asexual Reproduction‣ Genetically identical offspring from single parent‣ Reproduction for single-celled organisms‣ Method of growth/budding in multicelled organisms

2. Sexual Reproduction‣ Offspring inherits genetic material from each parent‣ Offspring formed by fusion of special reproductivecells

c. Comparing asexual/Sexual Reprod.AsexualSexualGenetically identical offspringGenetically diverse offspringQuick reprod. w/large # of offspringDiversity advantageous w/envirn.change

10.2 The process of Cell DivisionA. Chromosomes:◦ Bundled packages of DNA carrying cells genetic info

B. Prokaryotic chromosomes‣ Single circular DNA strand in cytoplasm1. Cell Cycle: rapid growth/DNA replication/division‣Division regulated by cell size‣Binary fission: cell pinches in (two geneticallyidentical cells)

C. Eukaryotic Chromosomes:‣ More DNA w/multiple chromosomes (humans=46)‣ Chromatin: material making up chromosomes (DNAcoiled around proteins called histones)‣ Nucleosomes: beadlike structure of chromosomes‣ Condense & become visible during division‣ Chromosomes ensure precise division of DNA

1. Eukaryote Cell Cycle◦ Stages cell goes thru (grows copies DNA divides)◦ Includes Interphase (G 1 , S, G 2 ), Mitosis & Cytokinesis

a) Interphase— “in-between”-majority of cell’s life1) G 1 (Gap 1 ) - cell growth size w/protein/organelles2) S (Synthesis) - chromosomes replicate, copying DNA3) G 2 - shortest phase, prep for division

) Mitosis:division of nucleus (quick process)1) Prophase—P is for poles, packing, & pieces‣Poles: centrioles to poles-form spindle fibers to sepchromosomes‣Packing: DNA condenses-duplicated sister chromatidsattached at centromere become visible‣Pieces: Nuclear envelope breaks up

2) Metaphase—M for “middle”‣Centromeres line up across center of cell‣Spindle fibers connect to dubl chrom centromere

3) Anaphase—A is for apart‣Centromeres split sister chromatids becomedaughter chromosomes

c) Cytokinesis: division of cytoplasm‣Occurs during telophase‣Plants: cell plate forms between nuclei dividing cells‣Animals: membrane pinches in until cytoplasm &organelles equally divided

Mitosis Visual Summary

10.3 Regulating Cell CycleA. Controls on Cell Division‣Skin, blood, bones cells divide thru out life‣W/injury: cells divide until contact other cells1. Cyclins: Proteins that regulating cell cycle‣Internal regulatory proteins: respond inside events(wastes build-up; chromo replctn before mitosis)‣External regulatory proteins: respond outside events• Ex: Growth factors (embryonic dev, wound healing)‣Apoptosis: programmed cell death (shapes bone,fingers)

B. Cancer: uncontrolled cell growth‣Division not regulated by cyclins‣Tumor – mass of cells (benign or malignant-spread)‣Block nerve connectn, steal nutrients, stop orgn functning‣Most cancers have defect in gene p53‣Halts cell cycle till all chromos replicated‣Damaged p53 cause cells to lose info for normal controls‣Treatmnt: removal (skin cancer), radiatn, chemothrpy

10.4 Cell DifferentiationA. Stem cells‣ Unspecialized cells which become differentiated cells1. Totipotent stem cells: can develop into any cell type‣ Fertilized egg/also cells of first few divisions2. Blastocyst: early hollow ball of cells‣ Pluripotent cells (inner cells): can become mostcell types (can not become placenta)‣ Embryonic Stem Cells: are pluripotent-can becomeall cells of body

3. Adult Stem Cells‣ Body contains pool of stem cells (skin, blood)‣ Are multipotent (more limited)‣ Cells of an organ/tissue typically become thatorgan/tissue