NE102 Lecture Notes 2

The cell cycle check points role of cyclins and

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The cell cycle Check points: role of cyclins and cyclin-dependent kinases during the cell cycle. The role for the cell cycle and related proteins in neurodegeneracy THE CELL CYCLE Cells reproduce by duplication their content and by generating 2 identical cells during  the cell cycle The phases of the cell cycle Interphase Cells make sure that everything is there in content and size G1 phase – vary from cell to cell Cell makes sure that the environment is correct to undergo mitosis Centrosomes are duplicated G1 checkpoint – is environment favorable? S phase DNA duplication Chromosomes are attached G2 phase  Cell makes sure that everything that has happened so far is correct G2 checkpoints Is all DNA replicated?
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Cell Division  Guest Lecture: Lucia Pastorino 19:00 Is all DNA damage repaired? M Mitosis and cytokinesis Mitosis checkpoints Are all chromosomes properly attached to the mitotic spindle? CYCLINS AND CYCLIN-DEPENDENT KINASES Cyclins and cyclin dependent kinases to regulate the progression of the cell cycle Cyclin activates CDK so that CDK can accept a phosphate group Specific binding between cyclin and cyclin-dependent kinas (CdK) S-Cyclins  Help cell go through G1-G2 phases Levels drop when M phase begins M-Cyclins Help cells go through M phase Levels low until cell enters M phase Deactivation of specific Cdks occurs by degradation of the partner cyclin Ubiquitinate the cyclin to degrade the cyclin-Cdk complex DNA damage: checkpoint in G2 phase to stop progression of the cell cycle X-rays causes DNA damage Activates protein kinases that phosphorylate p53, stabilizing and activating it. 
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Cell Division  Guest Lecture: Lucia Pastorino 19:00 MITOSIS During mitosis, chromosomes segregate into two newly formed cells, moving on the  mitotic spindle The chromosomes are pulled to the extremities of the spindles: a mechanism necessary  to allow cell division What generates the mitotic spindle? When does it form? Centrosomes duplicate during interphase and form the two poles of the mitotic spindle Mitotic spindle is formed when the polar microtubules organize and stabilize interacting  with one another Tubules of the mitotic spindle attach to the kinetochores around the centromere region  of the chromosomes.  Different phases Prophase  When the centrosomes separate and give origin to the mitotic spindle Prometaphase When the nuclear membrane breaks and chromosomes attach to the spindle Metaphase: when the chromosomes align on the spindle Anaphase: when the sister chromatids separate and chromosomes segregate Anaphase A: chromosomes are pulled pole-ward Anaphase B: poles are pushed and pulled apart
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