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How do cells grow & reproduce?

How do cells grow & reproduce?. In the Beginning – One Cell. Most of the organisms start out as one cell Humans start out as a single cell, the zygote , formed by uniting a sperm and egg The zygote divides to make trillions of cells

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How do cells grow & reproduce?

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  1. How do cells grow & reproduce?

  2. In the Beginning – One Cell • Most of the organisms start out as one cell • Humans start out as a single cell, the zygote, formed by uniting a sperm and egg • The zygote divides to make trillions of cells • During the process of dividing, cells become specialized to function in the various tissues and organs of the body = differentiation • Mitosis is the process of cell division in eukaryotic cells

  3. S G2 G1 Interphase M The Cell Cycle = Sequences of growth and division of a cell Two main parts: • Interphase – growth phase; takes most of the time • Mitosis – cell division phase

  4. Gap 1 - Doubling of cell size, increase in the number of organelles, regular cellular activities S - Synthesis of DNA S Gap 2 - Final preparation for division G1 G2 M Mitosis - Cell division The Cell Life Cycle G1, S, & G2 = Interphase = busy time

  5. S phase – DNA replication Fig. 3.26

  6. nucleolus is still visible INTERPHASE: nuclear envelope is clearly visible chromatin = uncoiled DNA http://www.fed.cuhk.edu.hk/~johnson/photomicrographs/mitosis/animal/animal_interphase.htm

  7. Interphase • Metabolic phase • Cell growth • DNA replication • Protein synthesis • Visible nucleus with CHROMATIN

  8. Nucleus with chromatin Condensed chromosomes Equator of the cell Interphase Poles of the cell Disappearing nuclear membrane Two daughter cells Prophase Mitotic spindle Metaphase Anaphase Telophase Stages of Mitosis Mother cell

  9. PROPHASE nuclear envelope disappears nucleolus disappears chromosomes become visible http://www.ac-dijon.fr/pedago/svt/documents/mitose/prophase.gif

  10. Prophase • Centrioles move to the opposite sides of cell • Spindle fibers from centrioles connect with chromosomes

  11. Prophase

  12. METAPHASE http://iccbweb.med.harvard.edu/mitchisonlab/Pages/mt.html

  13. METAPHASE chromatids Chromosomes line up at the equator of the cell spindle centriole http://www.chembio.uoguelph.ca/educmat/chm736/cycletx.htm Each chromatid is attached to a separate spindle fiber by its centromere

  14. Metaphase

  15. chromatids spindle centriole Nature (408. 423, 2000). http://www.blc.arizona.edu/courses/181gh/Lectures_WJG.01/mitosis_F.01/mitosis.html

  16. ANAPHASE http://www.univ-orleans.fr/SCIENCES/BIOCHIMIE/MMC/accueil.htm

  17. ANAPHASE early late Conly Rieder http://www.wadsworth.org/BMS/SCBlinks/WEB_MIT2/HOME.HTM

  18. ANAPHASE Chromatids separate and migrate to opposite poles http://www.blc.arizona.edu/courses/181gh/Lectures_WJG.01/mitosis_F.01/mitosis.html

  19. Anaphase

  20. TELOPHASE Daughter Nucleus Daughter Nucleus Spindles dissolve

  21. Telophase • Chromosomes uncoil • Two identical nuclei are formed (DNA is in the chromatin form) • Nuclear membrane & nucleolus reappear

  22. Cytoplasmic Division: Cytokinesis • Division of a cell’s cytoplasm to form two identical cells • Usually begins in late anaphase • Interphase begins when cytokinesis is complete

  23. A packaged chromosome Chromatid Identical chromatid (sister chromatid) Replication Anaphase Chromosomes, Chromatids & Centromeres Chromosome arm Two identical chromosomes Centromere Joins sister chromatids DNA doubling during S-phase Chromosome arm

  24. Results of Mitosis: Two new diploid cells with chromosomes that are identical to those of the parent cell Hmm… Why is it necessary for a cell’s chromosomes to be distributed to its daughter cells in such a precise manner?

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