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LEQ: How do eukaryotic cells divide?

LEQ: How do eukaryotic cells divide?. Key terms – interphase, chromosome, chromatin, phases of mitosis (various), cytokinesis Reading 5.3. LEQ: How do eukaryotic cells divide?. Activator: During which stage of the cell cycle is DNA copied? Explain how this process occurs. DNA and histones.

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LEQ: How do eukaryotic cells divide?

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  1. LEQ: How do eukaryotic cells divide? • Key terms – interphase, chromosome, chromatin, phases of mitosis (various), cytokinesis • Reading 5.3

  2. LEQ: How do eukaryotic cells divide? • Activator: • During which stage of the cell cycle is DNA copied? Explain how this process occurs.

  3. DNA andhistones DNA doublehelix SupercoiledDNA Chromatin Chromosomes condense at the start of mitosis. • A chromosome is a DNA molecule associated with protein. • DNA wraps around histone proteins that condense it. • Chromosomes come in duplicated and unduplicated forms

  4. chromatid telomere centromere telomere Condensed, duplicated chromosome • Chromatin – DNA coiled around histone proteins • Chromatid - One half of a duplicated chromosome • Sister chromatids (duplicated, right) - are held together at the centromere. • Telomeres (ends) - protect DNA and do not include genes.

  5. Focus on Mitosis: • The nucleus – when is it disassembled, when does it reappear? • Chromosomes – how do they move, when do chromatids separate? • Mitotic Spindle – how does it assist in mitosis?

  6. Parent cell centrioles spindle fibers centrosome nucleus with DNA Mitosis and cytokinesis produce two genetically identical daughter cells in many eukaryotes. • Interphase prepares the cell to divide. • G1 • S • G2

  7. Prophase - chromosomes condense, nucleus disassembles, spindle fibers form. • Mitosis divides the cell’s nucleus in four phases:

  8. Metaphase - chromosomes line up in the middle of the cell.

  9. Anaphase: sister chromatids separate, move to opposite sides of the cell.

  10. Focus: Anaphase chromosomes

  11. Telophase - nuclei form, spindle disassembles and chromosomes begin to uncoil.

  12. Animals: the membrane pinches closed. • Plants: a cell wall forms. • Cytokinesis differs in animal and plant cells.

  13. Parent cell centrioles spindle fibers centrosome nucleus with DNA A look ahead: Lab • Interphase • “I-ball”

  14. Prophase • “pile”

  15. Metaphase • “middle”

  16. Anaphase • “apart”

  17. Telophase • “two piles”

  18. Summary: • Briefly explain why the daughter cells resulting from binary fission and mitosis are genetically identical to each other and to the original cell. • How does mitosis accomplish the production of daughter cells. • Be sure to address how genetic information is acquired

  19. Answers: • Daughter cells are clones, the genetic information of the parent cell was copied and condensed into duplicated chromosomes, each consisting of two identical DNA molecules (sister chromatids). The chromatids are then separated during metaphase so that when the daughter cells begin to assemble their nuclei, each will have received a complete copy of the parent cell’s genetic information. • Prophase and telophase are opposites. The nuclear envelope fragments, chromosomes condense, and spindle fibers start to assemble in prophase. In telophase, the reverse occurs: the nuclear envelope reforms, chromosomes uncoil, and spindle fibers disassemble.

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