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Cell Reproduction

Cell Reproduction. Eukaryotic Cell Cycle. Cell cycle: repeating sequence of cellular growth and division during the life of the cell Interphase Mitosis Cytokinesis. Interphase. Cell is growing and preparing to divide G1 (First Gap) phase Cell grows rapidly S (synthesis) phase

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Cell Reproduction

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  1. Cell Reproduction

  2. Eukaryotic Cell Cycle • Cell cycle: repeating sequence of cellular growth and division during the life of the cell • Interphase • Mitosis • Cytokinesis

  3. Interphase • Cell is growing and preparing to divide • G1 (First Gap) phase • Cell grows rapidly • S (synthesis) phase • Cell’s DNA is copied • Each chromosome now has 2 identical chromatids • G2 (Second Gap) phase • Cell continues to grow and prepare for division • Microtubules form

  4. Mitosis • Process of dividing the nucleus into two daughter nuclei • Prophase • Metaphase • Anaphase • Telophase

  5. Prophase • Chromosomes condense • Nuclear membrane dissolves • Centrosomes (centrioles) move to opposite poles and spindle forms

  6. Metaphase • Condensed chromosomes line up at cell’s equator • Spindle fibers link the individual chromatids to opposite poles

  7. Anaphase • Spindle fibers shorten • Chromatids pulled to opposite poles of cell giving each pole identical sets of chromosomes

  8. Telophase • New nuclear envelope forms at each pole • Spindle dissolves • Chromosomes uncoil (chromatin)

  9. Cytokinesis • Cell membrane grows into the center of the cell and divides it into two daughter cells of equal size • each daughter cell has about half of the parent’s cytoplasm and organelles

  10. Cytokinesis • Animal cells: cell is pinched in half by a belt of protein threads • Plant cells: vesicles holding cell wall material line up in the middle to fuse into a cell plate which separates the new cells

  11. End Results • Two identical cells • New daughter cells half the size of the parent cell • Each cell enters G1

  12. Types of Cell Reproduction • Asexual: single parent passes a complete copy of its genetic information to each of its offspring • Offspring look identical to parent (MITOSIS)

  13. Types of Cell Reproduction • Sexual: two parents give genetic material to produce offspring that are genetically different from their parents (MEIOSIS) What are some advantages of sexual reproduction?

  14. Meiosis • Process in which a cell is divided and produces gametes (sperm or eggs): 2 rounds of division (P-I, M-I, A-I, T-I, then P-II, M-II, A-II, and T-II) • end with 4 haploid cells

  15. Homologous Chromosomes • Chromosomes that are similar in size, shape, and in kinds of genes that they contain • Each chromosome in a homologous pair comes from one of the two parents • Each species has a different number

  16. Chromosome Number • Gametes are haploid • Somatic cells are diploid Example: • Horse skin cell = 64 chromosomes = diploid (2n) • Horse egg cell = 32 chromosomes = haploid (n)

  17. Chromosome Number • Species: a population of organisms that are able to breed and produce fertile offspring • Same number of chromosomes

  18. Crossing Over • Prophase I • Chromatids exchange genetic material between homologous chromosomes during meiosis • What is the advantage of crossing over?

  19. Meiosis Two divisions to get 4 haploid cells

  20. Comparing Mitosis and Meiosis

  21. Comparing Mitosis and Meiosis

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