Eukaryotic cell cycle

This slide describes the various stages of the Eukaryotic cell cycle. The diagrams included here explains the various changes that take place during the mitotic division of a eukaryotic cell.

1. EUKARYOTIC CELL CYCLE - Different Phases and Molecular Events Submitted To: Submitted By: SOS Biotechnology Deepti Maheshwari Jiwaji University M.Sc. 1 st Semester JIWAJI UNIVERSITY

2. CONTENTS : INTRODUCTION CELL CYCLE PHASES OF CELL CYCLE

3. INTRODUCTION : Cell is the structural and functional unit of life. All cells arise from the pre existing cells, that is, a new cell comes into existence when the old cell divides. Cell division is one of the fundamental characteristics of a cell. Cells of all living organisms, ranging from the prokaryotic bacteria to the eukaryotic mammal, show repeated rounds of cell growth and division in a cyclic manner.

4. CELL CYCLE : Cell cycle refers to the ordered series of events that lead to the cell division and the production of two daughter cells, each containing chromosomes identical to those of the parental cell. The cell cycle is marked by two major chromosomal events: Duplication of chromosomes (S phase) Segregation of chromosomes and division of cell into two (M phase) A. B.

5. PHASES OF CELL CYCLE : G 1 Phase S Phase G 2 Phase M Phase INTERPHASE

6. G 1 PHASE AND G 2 PHASE: These are collectively called as Gap Phase. In this phase cells grow and double their mass of proteins and organelles. G1 Phase lies between M and S phase while G2 lies between S and M phase. Extracellular and intracellular conditions are checked to confirm whether or not they are in appropriate stage for cell to enter in next phase. If the prevailing conditions are not appropriate, then cell enters a RESTING STATE called as G (G Zero)Phase. G Zero Phase

7. 2 . S PHASE (Synthesis Phase) : Accurate copying of the entire DNA molecule of each chromosome occurs. Chromatin protein associated with the DNA also gets duplicated. At the end of S phase, sister chromatids remain glued to each other by the help of COHESIN protein . Ring formed by cohesin (A) (B)

8. 3 ) M PHASE: Segregation of duplicated chromosomes takes place. It is consists of two major events : Mitosis Prophase Pro- Metaphase Anaphase Telophase metaphase B. Cytokinesis:

9. A) MITOSIS: PROPHASE: Initiates with two chromosomal changes: a) Chromosome condensation b) Sister chromatid resolution CONDENSIN protein brings about the above two changes. Movement of duplicated centrioles (in S phase) towards the polar site. Formation of mitotic spindle takes place, which is a bipolar array of microtubules. Microtubules are of three types: Astral microtubule Interpolar microtubule Kinetochore microtubule

10. FIG: Three classes of microtubules of mitotic spindle in animal cell

11. Fig A: Diagrammatic representation of PROPHASE stage Fig B: Micrographic representation of PROPHASE stage

12. PROMETAPHASE: Breakdown of the nuclear membrane occurs to allow the attachment of spindle to the chromatids. Fig A: Diagrammatic representation of PROMETAPHASE stage Fig B: Micrographic representation of PROMETAPHASE stage

13. METAPHASE: Chromosomes are aligned at the equator of the spindle poles by the microtubules of mitotic spindle. Formation of METAPHASE PLATE takes place. Fig A: Diagrammatic representation of METAPHASE stage Fig B: Micrographic representation of METAPHASE stage

14. ANAPHASE: Chromosome segregation occurs. Completes in two stages : Kinetochore microtubule Spindle pole

15. Fig A: Diagrammatic representation of ANAPHASE stage Fig B: Micrographic representation of ANAPHASE stage

16. TELOPHASE: Disassembly of the mitotic spindle occurs. Reformation of nuclear envelope takes place . Fig A: Diagrammatic representation of TELO PHASE stage Fig B: Micrographic representation of TELOPHASE stage

17. B) CYTOKINESIS: Cytoplasm and cell organelle get divided and distributed to the newly formed daughter cells. Fig A: Diagrammatic representation of CYTOKINESIS stage Fig B: Micrographic representation of CYTOKINESIS stage

18. Cytokinesis in plant cell: Cytokinesis in animal cell: Chromatids Contractile ring made of actin and myosin Microtubule (A) (B)

19. REFRENCES : Molecular Biology Of The Cell (5 th Edition) by Bruce Alberts (page no. 1054-1090) Molecular Cell Biology (7 th Edition) by Harvey Lodish (page no. 804) The Cell a molecular Approach (4 th edition) by Geoffrey M.Cooper (pg no 677- 680)

20. THANK YOU AND HAVE A NICE DAY