Cell cycle regulation ppt

A cell cycle is a series of events that takes place in a cell as it grows and divides. The process has to be correct and regulated. This slide illustrated Cell cycle and its regulation. Check the slides to know more.

1. A Presentation on Cell Cycle Regulation Presented By:- ABHISHEK NAYAN M.SC LIFE SCIENCE Central University of south bihar

2. Cell Cycle Ordered series of events that lead to cell division and the production of two daughter cells, each containing chromosomes identical to those of the parent cell . Q:-When does cell starts to divide? When cell have reached the appropriate size and have synthesized the required proteins,they enter the cell cycle by crossing a point called START in yeast and RESTRICTION POINT in mammals.

3. Phases in Cell cycle G1 PHASE- Cell organelles increase in cell. synthesis of different types of proteins for DNA synthesis S PHASE- DNA synthesis phase. synthesis of histone proteins. G2 PHASE- 2 nd gap phase/pre mitotic phase preparation for M phase i.e synthesis of proteins, cell growth continues M PHASE- Starts with nuclear division separation of daughter chromosome(KARYOKINESIS) Ends with division of cytoplasm(CYTOKINESIS)

4. What is cell cycle regulation? Any process that controls the series of events by which a cell goes through the cell division. Importance- In unicellular organisms, cell division must be balanced with cell growth so that cell size is properly maintained. If several division occur before parent cells have reached the proper size, the daughter cells eventually become too small to be viable If cell grow too large before cell division the cells function improperly and the number of cells increase slowly. Loss of normal controls on cell replication results in development of cancer

5. REGULATION BY CHECKPOINTS Cell cycle is regulated by SURVEILLANCE MECHANISMS that monitor the order, integrity and fidelity of cell cycle. these include – growth to appropriate cell size replication and integrity of chromosomes their accurate segregation at mitosis The central mechanisms that drive cell cycle progression are CYCLIN DEPENDENT KINASES(CDKs). these are serine/threonine protein kinases that phosphorylates substrates to promote DNA and mitotic progressions.

6. CHECKPOINTS IN CELL CYCLE

7. G1 checkpoint G2 checkpoint spindle assembly checkpoint

8. DNA Damage Checkpoint Ensures that incomplete or damaged chromosomes are not passed on to daughter cells.

9. Spindle Assembly Checkpoint • Monitors assembly of the spindle and its attachment to Kinetochores • The kinetochore is the spindle-fiber attachment site on the Chromosome • Incorrect or unbalanced attachment to the spindle activates spindle checkpoint proteins, triggers a block in the separation of the sister chromatids by preventing activation of the anaphase promoting complex (APC/C)

10. Cyclins and their role in cell cycle Cyclins are a group of proteins that control cell cycle activities. Cyclin activate CDKs, which combine with the cyclins to modify certain proteins. These proteins that they modify are supposed to regulate the cell cycle. When a cyclin has finished modifying proteins, it is destroyed . If the cyclins malfunction through, the cell cycle will go wrong and a tumor could form.

11. Cyclin -CDK complex

12. Rb regulation of cell cycle The retinoblastoma protein is an inhibitor of cell cycle progression from the G1 to the S phase of the cell cycle. It acts through its ability to interact with cellular target molecules such as E2F transcription factors. The function of pRB is negatively regulated by a cell-cycle dependent phosphorylation catalyzed by cyclin -dependent kinases in the late G1 cell cycle phase.

13. Mitosis Promotion Factor

14. DEVELOPMENTS IN CELL CYCLE Hartwell both identified a particular class of genes that control the cell cycle, including the gene that controls ‘ start’,and introduced the concept of checkpoints. Nurse identified, cloned and characterized cyclin dependent kinase (CDK) in yeast and showed that the function of CDK is conserved in higher eukaryotes. Hunt discovered the cyclins and demonstrated that cyclins are degraded during the cell cycle. They were awarded Nobel Prize in Physiology or Medicine 2001 for their experiments that elucidated the master regulators of cell division in eukaryotes.

15. References- Karp, J.G. Cell and Molecular Biology. John Wiley & Sons, USA. Lodish , H., Berk , A., Zipursky , S.L., Matsudaria , P., Baltimore, D. and Darnell, J.( Eds ). Molecular Cell Biology Wikipedia NCBI- cell cycle regulation by checkpoints

16. Acknowledgements In preparation of my assignment, I had to take the help and guidance of some respected persons, who deserve my deepest gratitude. As the completion of this assignment gave me much pleasure, I would like to show my gratitude to Dr. Gautam Kumar  for giving me a good guidelines for assignment. I would also like to expand my gratitude to all those who have directly and indirectly guided me in writing this assignment. In addition, a thank you to Mr. Sameer Kumar- Helped with PowerPoint. Abinash Swain- Helped in understanding the topic. Abhisek Singh - Moral support.