Cell cycle

Cell Biology

1. SEMINAR PRESENTED ON Cell Cycle IN SESSION 2016-17 SUBMITTED BY: Mr. Prasannjeet Saha M.Sc. Semester 1 st Microbiology GUIDED BY: Miss. Chitra Bhattacharya (Asst. Prof) Dept. of MB/BT Department of Biotechnology & Microbiology Rungta College of Science & Technology, Durg 1

2. Contents Introduction Definition Phases of cell cycle Interphase Mitosis Cytokinesis Cell Cycle Checkpoints Conclusion Reference 2

3. Introduction Cell cycle presence in all living organism. The division cycle of most cells consists of four coordinated processes: Cell growth, DNA replication, distribution of the duplication chromosomes to daughter cell and cell division. The cell cycle is a sequence of cell growth and division. The time is takes to complete one cell cycle is the generation time. 3

4. Phases of cell cycle Cell cycle is process from the end of a cell division to the start of the next cell division. Eukaryotic cell cycle is divided approximately every 24 hours. The cell cycle is developed in two basic parts:- I n terphase And Mitosis. 4

5. Phases of Growth G 1 - Primary growth phase S - Synthesis; DNA replicate G 2 - Secondary growth phase *c ollectively these 3 stages are called “Interphase” M - Mitosis C - Cytokinesis 5

6. Fig. : Cell Cycle 6

7. Sketch of Cell Cycle DNA Copied Cells prepare for Division Cells Mature Daughter Cells Cell Divides into Identical cells 7

8. Interphase Interphase is the stage between two divisions. It is the longest phase. Interphase lasts for 89 hours. The interphase consists of three sub-stages. They are G 1 - Phase, S- Phase and G 2 -Phase. 8

9. Characters of Interphase It is the resting phase of the cell. It is the longest phase. The phase prepare the cell for mitosis. No division occurs in the phase. The metabolic activities are high in this phase 9

10. G1 - Phase The G1-phase is the gap period between a mitotic phase and the S-phage of the subsequent cycle. It is the Gap period & first growth period. Generally, this stage lasts for 25 to 50 % of the total interphase. During this phase RNAs(mRNA , rRNA and tRNA ) and proteins are synthesized. Nucleous produse rRNA . mRNA and tRNA . Cell growth . 10

11. S - Phase During this phase, DNA synthesis occurs. The DNA molecule duplicates. This period lasts for 35 to 40% if interphase. DNA replication occurs. Histones are synthesized. The histones cover each DNA strands. 11

12. G2 - Phase The G2-phaseis the gap period between S-phase and mitotic phase of a cell cycle. G2 is the second growth phase . The G2-phase is followed by mitotic phase. Intensive cellular synthesis. Mitochondria and Chloroplasts divide. Energy stores increase. 12

13. Mitotic Phase or M-Phase This is the division phase. M stands for mitosis . This phase is the short duration. Of this the M-phase has a duration of 45 minutes to one hour. Division of the nucleus. Also called Karyokinesis . Only occurs in eukaryotes. Has four stages. 13

14. Stages of M - Phase Prophase Metaphase Anaphase Telophase 14

15. 15 Stages Of Mitosis

16. Cytokinesis Cytokinesis is the process of cell division. Which divides the cytoplasm of a parental cell into two daughter cell. It occurs with two types of nuclear division called mitosis and meiosis. Which occur in animal cell . 16

17. Fig. : Cytokinesis 17

18. Regulation of the cell cycle of budding yeast The cell cycle of “ Saccharomyces cerevisiae ” is regulated primarily at a point in late G 1 called start. Passage trough start is controlled by the availability of nutrients, matting factors and cell size. These yeasts divide by budding buds from just after start. 18

19. Regulation of the cell cycle of budding yeast 19

20. Cell Cycle Checkpoint Several checkpoints function to ensure that complete genomes are transmitted to daughter cells. DNA damage checkpoints G1, S, and G2 lead to cell cycle arrest in response to damaged or unreplicated DNA. Another checkpoint, called the spindle assembly checkpoint, arrests mitosis if the chromosomes are not properly aligned on the mitotic spindle. 20

21. Fig : Cell Cycle Checkpoints 21

22. Conclusion Cell cycle present in all living organism, all cell are reproduce by dividing in to two with each parental cell giving rise to two daughter cell on completion of each cycle of cell division. 22

23. Reference Arumugam N., Biochemistry (2012), Fourth edition, Saras Publication, Camp road Periavilai , Kanyakumari Powar C.B., Cell Biology (2011), 23 th edition, Himalaya Publishing House, Girgaon , Mumbai 23

24. Thanks You 24