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Overview of Bacterial Binary Fission and Cell Cycle Phases

Understand the process of bacterial reproduction through binary fission and the phases of the cell cycle. Learn about DNA replication, mitosis, cytokinesis, and more. Discover exponential growth and the importance of genetic material in bacteria.

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Overview of Bacterial Binary Fission and Cell Cycle Phases

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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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