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Ch. 9.1: Cell Reproduction

Ch. 9.1: Cell Reproduction. Objectives: Describe how cell reproduction contributes to repair and to growth. Contrast asexual and sexual reproduction. Vocab.: asexual reproduction; sexual reproduction. Why do cells need to reproduce?. Repair and replacement of dead or damaged cells.

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Ch. 9.1: Cell Reproduction

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  1. Ch. 9.1: Cell Reproduction Objectives: Describe how cell reproduction contributes to repair and to growth. Contrast asexual and sexual reproduction. • Vocab.: asexual reproduction; sexual reproduction

  2. Why do cells need to reproduce? • Repair and replacement of dead or damaged cells. • Growth = increase in size

  3. Asexual Reproduction • Single cell duplicates its genetic material and then splits into 2 genetically identical cells. • 1 parent • Parent & offspring are identical • Most single celled organisms • Many multicellular have option (plants, marine organisms)

  4. Sexual Reproduction • Genetic material from 2 parent combines. • Offspring genetically different fr. parents • Involve sperm & egg • Meiosis involved

  5. Ch. 9.2: The Cell Cycle Objectives: Describe the structure of a chromosome. Name the stages of the cell cycle and explain what happens during each stage. • Vocab.: chromatin, chromosome, sister chromatid, centromere, cell cycle, interphase, mitotic phase, mitosis, cytokinesis

  6. 9.2: Cell Cycle

  7. 9.2: Chromosomes & Cell Division Chromatin = long fibers of DNA + proteins Chromatin --> Chromosomes before cell divides Chromosomes: Condensed threads of genetic material formed fr. Chromatin as a cell prepares to divide. Humans: 46 chromosomes (23 pair)

  8. 9.2: Chromosomes & Cell Division Sister Chromatids: 1 pair of identitical chromosomes created before a cell divides. Centromeres: Where 2 sister chromatids are joined.

  9. 9.2: Cell Cycle Interphase: When cell is not dividing. Carrying out metabolic fxns, grow, etc. ~ 90% of cell life S: DNA duplicated

  10. 9.2: Mitosis Mitosis Stage of the Cell cycle where cell is DIVIDING. (M phase) Mitosis: Nucleus & duplicated chromosomes divide. Cytokinesis: Cytoplasm divides into 2.

  11. Ch. 9.3: Mitosis • Division of somatic cells (body) Daughter Cells Somatic Cell

  12. Chromosomes • Strands of DNA • Each human has 23 pair (diploid or 2n) • One from your mother • One from your father

  13. Chromosome DNA molecule with attached proteins Sister chromatids One from Mom One from Dad Look at figure 8.2

  14. Mitosis • First you duplicate DNA • Why? • You have 2 pairs of 23 chromosomes • If cell splits, you will only have 1 pair • Duplicate DNA, cell splits, still have 2 pair Sex chromosomes- X and Y: XX is female in humans, XY is male

  15. Interphase • Prior & After Mitosis • G1 period • 90% of cell life spent here • Cell goes about it’s business • S period • DNA is duplicated • G2 period • Cell prepares to divide • Cannot see DNA- uncoiled as chromatin

  16. 1. Prophase • DNA becomes visible as chromosomes • Nuclear membrane dissolves • Centrioles migrate to opposite poles • Spindle fibers form Easy to remember- Prophase- proceeding into mitosis

  17. 2. Metaphase Pole • Spindle fibers attach to centromeres • Chromosomes line up at midline of the cell Spindle Equator Pole Easy to remember- metaphase, DNA at middle

  18. 3. Anaphase • Spindle fibers pull apart centromeres • One chromatid goes to each centriole (they look like V’s) Easy to remember- anaphase, apart they go

  19. 4. Telophase • Chromatids reach centrioles • Mitosis ends when new nuclear membranes form • Some evidence of cell dividing Easy to remember- telophase, terminal phase

  20. Last part- Cytoplasmic division • Technically not in mitosis • Animal cell- pinching of cell membrane- cleavage • Plant cell- formation of new cell wall- cell plate • DNA becomes non-visible, back to chromatin • Daughter cells enter G1 period of interphase

  21. Cancer • Uncontrollable mitosis (no G1) • Cells cease to do what they are supposed to be doing in favor of dividing. • Pancreatic cancer- no longer in interphase • Cease production of insulin • Incomplete digestion of food • Diabetes, abdominal pain, weight loss • Cancer does not “poison” your body…

  22. Henrietta Lacks • 1951, a poor 31 Year old African American mother of 4 was dying of cervical cancer @ Johns Hopkins Hospital • Dr. George Gey- sampled some of the cancerous cells, found they could live indefinitely and multiply outside the body • She died 6 months later, but cells live on • HeLa cells • Used to study many different diseases • Cure for Polio

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