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Chapter 6-

Chapter 6-. Cell cycle-growth. Reproduction of Bacteria. BINARY FISSION. Completed. Bacteria dividing. Reproduction of Bacteria. The time of reproduction depends on how desirable the conditions are. (example- leaving milk out vs keeping them in the refridgerator )

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Chapter 6-

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  1. Chapter 6- Cell cycle-growth

  2. Reproduction of Bacteria BINARY FISSION Completed Bacteria dividing

  3. Reproduction of Bacteria • The time of reproduction depends on how desirable the conditions are. (example- leaving milk out vs keeping them in the refridgerator) • Some can reproduce every 20 minutes • (one bacteria could be an ancestor to millions in less than a day) • “EXPONTENTIAL GROWTH”

  4. Bacterial Cell & Nucleiod DNA Ring Step 1 DNA replicates Step 2 DNA (chromosomes) move to opposite ends and attach to cell membrane Binary Fission Step 3-Cell grows in the middle Step 4 – Cell wall forms between the two daughter cells

  5. Cell Cycle • Stages in growth & division • G1 Phase • S Phase • G2 Phase • M Phase • Cytokinesis

  6. G1 Phase • First growth stage • Cell increases in size • Cell copies all of its organelles

  7. Synthesis Phase (Replication) • Copying of all of DNA’s instructions • Chromosomes duplicated

  8. CHROMOSOMES- preparing for cell division- make copies of itself CHROMATIDS- identical copies of DNA (each chromosome will turn into 2 chromatids) CENTROMERE- center where the two identical halves are attached

  9. G2 Phase • Time between DNA synthesis & mitosis • Cell continues growing • Needed proteins produced • Organelles move to opposite ends of cell

  10. M Phase (MITOSIS) division of the nucleus- in 4 steps • Cell growth & protein production stop • Cell’s energy used to make 2 daughter cells • Called mitosis or karyokinesis (nuclear division)

  11. PROPHASE • CHROMATIN condenses into CHROMOSOMES- two identical chromosomes are attached at the center called a CENTROMERE • CENTRIOLES- move to opposite poles and produce SPINDLE FIBERS • SPINDLE FIBERS appear and attach to centromeres • NUCLEAR MEMBRANE- starts to disintegrate • NUCLEOLUS disappears

  12. METAPHASE SPINDLE FIBERS align the chromosomes in the middle of the cell ( “meet” at the equator)

  13. ANAPHASE Individual chromosomes get pulled apart at the centromere and are carried to opposite poles via spindle fibers (pulled “apart”)

  14. TELOPHASE • CHROMOSOMES thin out into chromatin again • SPINDLE FIBERS disappear • NUCLEAR MEMBRANE- starts to form making two new nuclei • NUCLEOLUS reappears

  15. Cytokinesis • Occurs after chromosomes separate • Forms two, identical daughter cells

  16. CYTOKINESIS CLEAVAGE FURROW develops- Cell membrane begins forming and grows outwardly to meet the rest of the cell membrane-

  17. G 0 cycle • Cells exiting the cell cycle • DNA is no longer copied • there is no growth • Example-fully developed brain cells (neurons)

  18. Human Chromosomes

  19. KARYOTYPE (Pg 147) • A photomicrograph of the chromosomes in a dividing cell. • Chromosomes are paired up and arranged in order from longest to shortest

  20. HOMOLOGOUS CHROMOSOMES • Two copies of each chromosome. • (one copy of each chromosome from each parent)

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