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The Cell Cycle

The Cell Cycle. Sections 5.1-5.2. The cell cycle is a regular pattern of growth, DNA replication, and cell division. Four Main Stages. The cell cycle has four main stages: Gap 1 (G1) Synthesis (S) Gap 2 (G2) Mitosis (M) Prophase Metaphase Anaphase Telophase Cytokinesis. Interphase.

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The Cell Cycle

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  1. The Cell Cycle Sections 5.1-5.2

  2. The cell cycle is a regular pattern of growth, DNA replication, and cell division.

  3. Four Main Stages • The cell cycle has four main stages: • Gap 1 (G1) • Synthesis (S) • Gap 2 (G2) • Mitosis (M) • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis Interphase

  4. First Stage: Gap 1 (G1) • Cell carries out normal functions • Ex: skeletal muscle cell contracts to move joints • Cells also continue to grow during this stage. • Cells spend most of their time in this stage. • Length of this stage depends on the type of the cell

  5. Second Stage: DNA synthesis (S) • DNA is copied • At the end of the synthesis stage, the cell nucleus contains two complete sets of DNA.

  6. Third Stage: Gap 2 (G2) • Cells continue to carry out their normal functions • Additional growth occurs

  7. Fourth Stage: Mitosis (M) • Includes two processes: • Mitosis • division of the cell and its contents • During mitosis, the nuclear membrane dissolves, the duplicated DNA condenses around proteins and separates, and two nuclei form. • Cytokinesis • Process that divides the cell cytoplasm • Result is two daughter cells that are genetically identical to the original cell.

  8. Mitosis occurs only if the cell is large enough and the DNA undamaged. • Cells divide at different rates. • The rate of cell division varies with the need for those types of cells. • Some cells are unlikely to divide (G0).

  9. Cell size is limited. • Volume increases faster than surface area. • Surface area must allow for adequate exchange of materials. • Cell growth is coordinated with division. • Cells that must be large have unique shapes.

  10. Condensed, duplicated chromosome Chromosomes telomere chromatid • DNA plus proteins is called chromatin. • One half of a duplicated chromosome is a chromatid. • Sister chromatids are held together at the centromere. • Telomeres protect DNA and do not include genes. • Chromosomes condense at the start of mitosis. centromere telomere

  11. Parent cell centrioles spindle fibers centrioles nucleus with DNA • Cells divide during mitosis and cytokinesis. • Mitosis and cytokinesis produce two genetically identical daughter cells. • Interphase (G1, S, G2) prepares the cell to divide. • During interphase, the DNA is duplicated.

  12. 4 Phases of Mitosis • Prophase • Metaphase • Anaphase • Telophase • PMAT Remember this… Please Make ATaco

  13. Prophase • Chromatin condenses into chromosomes (consisting of two identical sister chromatids). • Nuclear envelope breaks down • Nucleolus disappears • Centrosomes and centrioles begin to move to opposite sides of the cell • Spindle fibers form from the centrioles

  14. Interphase -> Prophase

  15. Metaphase • Spindle fibers attach to the centromere of each chromosome. • Chromosomes align along the cell equater • Meta=Middle

  16. Prophase -> Metaphase

  17. Anaphase • Sister chromatids separate from each other. • Spindle fibers begin to shorten, which pulls the sister chromatids away from each other and toward opposite sides of the cell.

  18. Metaphase -> Anaphase

  19. Telophase • Complete set of identical chromosomes is positioned at each pole of the cell. • Nuclear membranes start to form • Chromosomes begin to uncoil • Spindle fibers fall apart

  20. Anaphase -> Telophase

  21. Cytokinesis • Divides the cytoplasm into two daughter cells, each with a genetically identical nucleus • Completion of one full stage of the cell cycle • Differs in animal and plant cells • In animal cells, cleavage furrow forms pinching the membrane closed. • In plant cells, a cell plate forms. • Cells enter interphase and the cylces begins again

  22. Telophase -> Cytokinesis

  23. Formation of New Cells… • Critical in both multicellular and single-celled organisms • Single-celled organisms use cell division to reproduce • Multicellular organisms use it for growth, development, and repair.

  24. Cell Cycle Book Directions • Title Page: Your name • Interphase: picture, description, label…nucleus, chromatin, centrioles, and spindle fibers • Mitosis: definition • Prophase: picture, description, label…nuclear membrane, chromosomes, centrioles, and spindle fibers

  25. Cell Cycle Book Directions • Metaphase: picture, description, label… chromosomes, centrioles, and spindle fibers • Anaphase: picture, description, label…chromatid, centrioles, and spindle fibers • Telophase: picture, description, label…nuclear membrane, chromatid, centrioles, and spindle fibers • Cytokinesis: picture, description, label…nucleus, chromatin, and centrioles

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