Chapter 5 Cell Division

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1 Chapter 5 Cell Divisio 5.1 Cell Icrease ad Decrease Cell divisio icreases the umber of somatic cells (body cells) Zygote Adult huma (sigle cell) (trillios of cells) The Cell Cycle 5.1 Cell Icrease ad Decrease Orderly set of stages that occur betwee the time a cell divides ad the time the resultig daughter cells divide The Cell Cycle 5.1 Cell Icrease ad Decrease Iterphase G 1 S DNA replicatio G 2 Mitotic Stage Mitosis divisio of the ucleus Cytokiesis divisio of the cytoplasm

2 S growth ad DNA replicatio G 2 G 1 growth ad fial growth preparatios for M divisio Cytokiesis Aaphase Telophase Iterphase Metaphase Late prophase Prophase 5.2 Cotrol of the Cell Cycle ad Cacer Cell Cycle cotrolled by Iteral sigals has cell followed ormal sequece of stages? Exteral sigals should cell divide or ot? a. 5.2 Cotrol of the Cell Cycle ad Cacer Checkpoits are critical for prevetig cacer developmet A damaged cell should ot complete mitosis, but istead should udergo apoptosis (cell suicide) 5.2 Cotrol of the Cell Cycle ad Cacer Carciogeesis - developmet of cacer Multi-stage process Ivolves disruptio of ormal cell divisio ad behavior Mutatio iitiates cacer Proto-ocogees Tumor suppressor gees

5.2 Cotrol of the Cell Cycle ad Cacer growth factor

cell cycle ad prevet apoptosis Gas pedal of car cell

causig gees Gas pedal is always pressed dow Proteis for

pathway DNA Proteis for cell divisio Mutated Ras protei

2 Cotrol of the Cell Cycle ad Cacer Tumor suppressor gees

apoptosis Brakes of a car ihibit progressio through cell

3 5.2 Cotrol of the Cell Cycle ad Cacer growth factor receptor Proto-ocogees Ecode proteis that promote the cell cycle ad prevet apoptosis Gas pedal of car cell cotiues through cycle Mutate to become ocogees Cacer causig gees Gas pedal is always pressed dow Proteis for cell divisio Activatio Activated Ras protei Sigalig pathway DNA Proteis for cell divisio Mutated Ras protei Sigalig pathway DNA a. b. 5.2 Cotrol of the Cell Cycle ad Cacer Tumor suppressor gees Ecode proteis that stop the cell cycle ad promote apoptosis Brakes of a car ihibit progressio through cell cycle Mutatio causes the brakes ot to work Gee products do o ihibit cell cycle 5.3 Maitaiig the Eukaryotic s are composed of chromati Combiatio of DNA ad protei Dispersed i ucleus of o-dividig cell Codeses ito compact form for cell divisio

5.3 Maitaiig the Each species has a characteristic

type of Huma body cells = 46 i 23 pairs Haploid (1):

which umber stays costat Oe 2 cell becomes two 2

duplicated is composed of 2 sister chromatids held

divides ad each chromatid becomes a daughter cetriole

INTERPHASE replicatio cetromere cetromere duplicated

4 5.3 Maitaiig the Each species has a characteristic umber Diploid (2): Cells have two (a pair) of each type of Huma body cells = 46 i 23 pairs Haploid (1): Cells have half the diploid umber of s Huma eggs or sperm = 23 or 1 member of each pair 5.3 Maitaiig the Overview of Mitosis Nuclear divisio i which umber stays costat Oe 2 cell becomes two 2 cells DNA replicatio produces duplicated s Each duplicated is composed of 2 sister chromatids held together by a cetromere Durig mitosis, the cetromere divides ad each chromatid becomes a daughter cetriole sister chromatids 2 = 4 DNA REPLICATION DURING INTERPHASE replicatio cetromere cetromere duplicated cosistig of two sister chromatids cosistig of oe chromatid divisio duplicated MITOSIS 2 = 4 2 = 4 2 = 4

S growth ad DNA replicatio G 2 G 1 growth ad fial growth preparatios for M divisio Cytokiesis

3 Maitaiig the Mitosis i aimal cells Prophase Nuclear membrae disappears, cetrosomes migrate,

Cetrosomes have duplicated. Chromati is codesig ito s, ad the uclear evelope is fragmetig. 20!

!m pole cetromere cetromere spidle fibers formig cetromeric spidle fiber polar spidle fiber

Cetrosomes begi movig apart, ad spidle is i process of formig.

Late Prophase The cetromere of each chromatid is attached to a cetromeric spidle fiber.

5 S growth ad DNA replicatio G 2 G 1 growth ad fial growth preparatios for M divisio Cytokiesis Aaphase Telophase Iterphase Metaphase Late prophase Prophase 5.3 Maitaiig the Mitosis i aimal cells Prophase Nuclear membrae disappears, cetrosomes migrate, spidle fibers appear Chromati codeses ad s ow visible Each composed of 2 sister chromatids Cetromeres attach to spidle fibers a. MITOSIS uclear evelope fragmets chromati codeses ucleolus disappears aster Early Prophase Cetrosomes have duplicated. Chromati is codesig ito s, ad the uclear evelope is fragmetig. 20!!m duplicated 20!!m spidle 9!!m pole cetromere cetromere spidle fibers formig cetromeric spidle fiber polar spidle fiber Prophase Nucleolus has disappeared, ad duplicated s are visible. Cetrosomes begi movig apart, ad spidle is i process of formig. (early prophase, prophase): Ed Reschke; (late prophase): Michael Abbey/Photo Researchers, Ic. Late Prophase The cetromere of each chromatid is attached to a cetromeric spidle fiber. Polar spidle fibers stretch from each spidle pole ad overlap. 5.3 Maitaiig the Metaphase Chromosomes lie up at metaphase plate Aaphase Cetromeres divide, sister chromatids pulled to opposite poles by fibers Telophase Nuclear membrae reforms, spidle disappears, cytokiesis occurs Chromosomes become more diffuse agai

cetromeric spidle fiber 6.2!m 6.2!m 6.2!m 25!

6 s at metaphase plate 20!m daughter 20!m cleavage furrow 16!m MITOSIS i Plat Cells Prophase Metaphase Aaphase Telophase ucleolus cetromeric spidle fiber 6.2!m 6.2!m 6.2!m 25!m cell wall Chromosomes spidle fibers cell plate Metaphase Cetromeres of duplicated s are aliged at the metaphase plate (ceter of fully formed spidle). Cetromeric spidle fibers attached to the sister chromatids come from opposite spidle poles. Aaphase Sister chromatids part ad become daughter s that move toward the spidle poles. I this way, each pole receives the same umber ad kids of s as the paretal cell. Telophase Daughter cells are formig as uclear evelopes ad ucleoli reappear. Chromosomes will become idistict chromati. (metaphase, aaphase, telophase)): Ed Reschke 5.3 Maitaiig the cleavage furrow Cytokiesis i Aimal Cells Cleavage furrow forms betwee daughter uclei Cotractile rig cotracts deepeig the furrow Cotiues util separatio is complete cotractile rig

7 5.4 Reducig the 5.4 Reducig the Meiosis Occurs i the life cycle of sexually reproducig orgaisms Reduces the umber Provides offsprig with a differet combiatio of traits from that of either paret Overview of Meiosis Begi with 1 diploid cell 2 divisios Ed with 4 haploid daughter cells Pairs of s are called homologues 5.4 Reducig the Overview of Meiosis Meiosis I Homologues lie up side by side at equator syapsis Whe pairs separate, each daughter cell receives oe member of the pair Cells are ow haploid 5.4 Reducig the Overview of Meiosis Meiosis II No replicatio of DNA occurs betwee meiosis I ad meiosis II Cetromeres divide ad sister chromatids migrate to opposite poles to become idividual s Each of the four daughter cells produced has the haploid umber Each is composed of oe chromatid

8 cetromere ucleolus cetrioles homologous pair syapsis sister chromatids MEIOSIS I Homologues syapse ad the separate. MEIOSIS II DNA REPLICATION Sister chromatids separate, becomig daughter s. homologous pair 2 = 4 2 = Reducig the Overview of Meiosis Fertilizatio Daughter cells of meiosis become gametes Sperm ad eggs Fertilizatio restores the diploid umber + = 2 = 2 = Reducig the Meiosis helps esure geetic variatio Geetic recombiatio occurs i two ways Crossig Over Idepedet Assortmet Crossig Over Durig Prophase I sister chromatids syapsis of homologues crossig- over betwee osister chromatids chromatids after exchage recombiat daughter s

9 Idepedet Assortmet Durig Metaphase I 5.4 Reducig the Phases of Meiosis I Prophase I Syapsis occurs, uclear membrae breaks dow Homologues lie up side by side ad crossig over occurs Metaphase I Homologous pairs lie up at metaphase plate such that materal or pateral member may be orieted toward either pole 5.4 Reducig the 2 = 4 DNA REPLICATION MEIOSIS I Prophase I Homologous s pair durig syapsis. Metaphase I Homologous pairs alig at the metaphase plate. Phases of Meiosis I Aaphase I Homologous s (each still cosistig of 2 chromatids) udergo idepedet assortmet ito daughter cells Telophase I may or may ot happe Nuclear evelope may re-form Cytokiesis may happe producig 2 daughter cells which are haploid

Aaphase I Homologous s separate, pulled to opposite poles by

4 Reducig the Iterkiesis Period of time betwee Meiosis I ad

4 Reducig the Phases of Meiosis II Prophase II Cells have oe

the metaphase plate Aaphase II Cetromeres divide ad daughter s

occurs MEIOSIS II = 2 = 2 Prophase II Cells Metaphase II

Aaphase II Daughter s Move toward the poles.

10 Aaphase I Homologous s separate, pulled to opposite poles by cetromeric spidle fibers. 5.4 Reducig the Iterkiesis Period of time betwee Meiosis I ad Meiosis II No replicatio of DNA = 2 Telophase I Daughter cells have oe from each homologous pair. = 2 Iterkiesis Chromosomes still cosist of two chromatids. 5.4 Reducig the Phases of Meiosis II Prophase II Cells have oe from each homologous pair Metaphase II Chromosomes lie up at the metaphase plate Aaphase II Cetromeres divide ad daughter s migrate toward the poles Telophase II Nuclei form, cytokiesis occurs MEIOSIS II = 2 = 2 Prophase II Cells have oe from each homologous pair. Metaphase II Chromosomes alig at the metaphase plate. Aaphase II Daughter s Move toward the poles. Telophase II Spidle disappears, uciel form, ad cytokiesis takes place. = 2 Daughter Cells Meiosis results i four haploid daughter cells. = 2

5.4 Reducig the Meiosis produces haploid cells Not idetical to paret cell Combiig of s from geetically differet gametes at fertilizatio esures offsprig are ot idetical to parets This geetic

11 5.4 Reducig the Meiosis produces haploid cells Not idetical to paret cell Combiig of s from geetically differet gametes at fertilizatio esures offsprig are ot idetical to parets This geetic variability is the mai advatage of sexual reproductio 5.5 Compariso of Meiosis With Mitosis DNA replicatio occurs oly oce prior to either meiosis ad mitosis Meiosis requires two divisios, mitosis oly oe Meiosis produces four daughter cells, mitosis produces two 5.5 Compariso of Meiosis With Mitosis 4 daughter cells from meiosis are haploid, 2 from mitosis are diploid Daughter cells from meiosis are geetically variable, while those from mitosis are geetically idetical Meiosis oly occurs at certai times of the life cycle while mitosis is almost cotiual. Meiosis II Meiosis I MEIOSIS Prophase I Syapsis ad crossig- overoccur. Metaphase I Homologues alig idepedetly. Aaphase I Homologues separate. Telophase I Daughter cells form. Sister chromatids separate. Daughter uclei are ot geetically idetical to paretal cell. MITOSIS Prophase No syapsis. Metaphase Chromosomes alig at the metaphase plate. Aaphase Sister chromatids separate. Telophase Daughter cells form. Daughter uclei are geetically idetical to paretal cell.

TABLE 5.1 Compariso of Meiosis I with Mitosis Meiosis I Prophase I Pairig of homologous s Metaphase I Homologous duplicated s at metaphase plate Aaphase I Homologous s separate.

Telophase/Cytokiesis Two daughter cells, idetical to the paretal cell TABLE 5.

12 TABLE 5.1 Compariso of Meiosis I with Mitosis Meiosis I Prophase I Pairig of homologous s Metaphase I Homologous duplicated s at metaphase plate Aaphase I Homologous s separate. Telophase I Two haploid daughter cells Mitosis Prophase No pairig of s Metaphase Duplicated s at metaphase plate Aaphase Sister chromatids separate, becomig daughter s that move to the poles. Telophase/Cytokiesis Two daughter cells, idetical to the paretal cell TABLE 5.2 Compariso of Meiosis II with Mitosis Meiosis II Prophase II No pairig of s Metaphase II Haploid umber of duplicated s at metaphase plate Aaphase II Sister chromatids separate, becomig daughter s that move to the poles. Telophase II Four haploid daughter cells, ot idetical to paretal cell Mitosis Prophase No pairig of s Metaphase Duplicated s at metaphase plate Aaphase Sister chromatids separate, becomig daughter s that move to the poles. Telophase/Cytokiesis Two daughter cells, idetical to the paretal cell MITOSIS 5.6 The Huma Life Cycle MITOSIS Requires both mitosis ad meiosis 2 Meiosis i the female is called oogeesis Meiosis i the male is called spermatogeesis At fertilizatio, the resultig zygote divides by mitosis for the processes of growth ad developmet MEIOSIS 2 = 46 diploid (2) haploid () = 23 zygote FERTILIZATION Mitosis is used for repair throughout life egg sperm

5.6 The Huma Life Cycle Spermatogeesis Occurs i testes Begis at puberty ad cotiues throughout life Primary spermatocytes (2) divide i meiosis I to form two secodary spermatocytes (1) Secodary

13 5.6 The Huma Life Cycle Spermatogeesis Occurs i testes Begis at puberty ad cotiues throughout life Primary spermatocytes (2) divide i meiosis I to form two secodary spermatocytes (1) Secodary spermatocytes divide i meiosis II to produce four spermatids Spermatids the mature ito sperm (spermatozoa) SPERMATOGENESIS Meiosis I Meiosis II Metamorphosis ad maturatio primary spermatocyte 2 secodary spermatocytes spermatids sperm 5.6 The Huma Life Cycle Oogeesis Begis i the fetus Primary oocytes are arrested i prophase I At puberty, oe primary oocyte cotiues the process of meiosis durig each mestrual cycle 5.6 The Huma Life Cycle Oogeesis (cot.) Primary oocyte (2) divides i meiosis I to produce oe secodary oocyte (1) ad oe polar body (1) Divisio is uequal as secodary oocyte receives most of the cell cotets ad half the s

14 5.6 The Huma Life Cycle Oogeesis (cot.) If the secodary oocyte is fertilized, meiosis II will proceed Aother uequal divisio will occur, the egg receivig most of the cytoplasm A secod polar body is also formed If the secodary oocyte is ot fertilized, it disitegrates OOGENESIS Meiosis I Fertilizatio Meiosis II first polar body secod polar body sperm ucleus primary oocyte 2 secodary oocyte Meiosis II is completed after etry of sperm egg zygote 2

Interphase. Chapter 10 Notes. Objective 1: Summarize the events that occur during mitosis

Interphase. Chapter 10 Notes. Objective 1: Summarize the events that occur during mitosis Chapter 10 Notes Ratio of Surface Area to Volume i Cells 10 1 Cell Growth A. Limits to Cell Growth 1. DNA Overload 2. Exchagig Materials 3. Ratio of Surface Area to Volume 4. Cell Divisio Cell Size Surface