Lecture 4 Cell Cycle.ppt -...

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CHAPTER 17 1 Cell Cycle
Table of contents 2 Cell Cycle Basic concepts in the cell cycle Classical methods to study cell cycle The cell cycle control system Checkpoints Cyclins and Cyclin-dependent kinases Controlling S phase Controlling M phase Sister-chromatid condensation Spindle assembly and function Spindle interaction with chromosomes Moving chromosomes to poles Forces Separation and segregation Cytokinesi Basic structures and concepts Regulation of cytokinesis Control of Cell Division and Cell Growth Mitogens Mitogen signaling pathways Mitogen suppressors Cell Growth PI 3-kinase and mTOR Division and growth coordination Limiting growth
The Cell Cycle 3 Cell Cycle Cell division necessary to build organisms Concepts: Cell cycle stages S and M phases critical stages of cell cycle M phase events
Figure 17-4 Molecular Biology of the Cell (© Garland Science 2015) The four stages of the cell cycle G1 Phase: growth phase after division S Phase: if growth factors are present, cell replicates DNA G2 Phase: second round of growth before division M Phase: division of DNA (mitosis) and cytoplasm (cytokinesis) to form two cells 4 Cell Cycle
Figure 17-2 Molecular Biology of the Cell (© Garland Science 2015) S and M phases are the main components of the cell cycle 5 Cell Cycle DNA replication generates identical sister- chromatids – sister chromatids remain attached to each other: centromere Mitosis: permits the even separation of the sister chromatids and organelles to daughter cells Cytokinesis: splits the cell into two daughter cells
Figure 17-3 Molecular Biology of the Cell (© Garland Science 2015) The sequence of events in M phase 6 Cell Cycle Prophase: nuclear envelope breakdowns and sister chromatids are disentangled and condensed Prometaphase: spindle microtubules attach and begin to align the condensed chromosomes Metaphase: chromosomes are aligned at the centre of the cell (spindle equator) Anaphase: sister chromatids lose cohesion and are segregated to opposite poles Telophase: chromatids decondense, nuclear envelope reforms and cell initiates cytokinesis
SELF-STUDY SECTION I: “Cell-cycle progression can be studied in various ways” 7 Cell Cycle Self-study section pg. 966-967. Figures 17-5 to 17-8
The cell-cycle control system 8 Cell Cycle Concepts: Cell cycle checkpoints Checkpoints controlled by CDKs CDKs are regulated by CAKs and CIKs CDKs are regulated by cyclins Cyclins are regulated by expression and degradation
Figure 17-9 Molecular Biology of the Cell (© Garland Science 2015) The cell-cycle checkpoints 9 Cell Cycle Cells have mechanisms to ensure conditions are ideal to enter a specific cell cycle phase or if a phase is completed.

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