Cell Cycle (Biology) Powerpoint Presentation, Slides of Biology

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CELL CYCLE

Definition

◦ The sequence of events by which a Cell duplicates its genome. Synthesizes other constituents of the cell and eventually divides into two daughter cells is termed as cell cycle.

Interphase

• Interphase is a phase between two successive M phase, where the cell prepares itself for cell division. It is the biosynthetic phase in which the cell duplicates its organelles and replicates its DNA.
• It consumes more than 95% duration of cell cycle.

Interphase division:

◦ Interphase is further dividied into three phases:

1. Gap 1 phase- It is the gap between previous mitosis and DNA replication of the next cell cycle.
2. S phase- In this phase DNA replication takes place. The DNA content of the cell doubles and centriole duplicates.
3. Gap 2 phase- Cell continues to grow and prepares for mitosis. Protein synthasis takes place.

stages of mitosis

Mitosis consists of 4 basic stages:

◦Prophase

◦Metaphase

◦Anaphase

◦telophase

During metaphase :

◦ Spindle fibres attach to kinetochores of chromosomes.

◦ Chromosomes are moved to spindle eqyator to fprm metaphasic plate.

During anaphase the following events occur:

◦ Centrosomes split and chromatids separate.

◦ Chromatids move to opposite poles.

CYTOKINESIS

Definition

◦ Cytokinesis is a stage where the cytoplasm of parent cell divides

into two daughter cells. This process is different in plants and animals. Hence, it is the final stage of cell divison.

Conclusion

◦ It thereby ensures that chromosomes number are maintained from parent cell to daughter cell. It differs from animal cytokinesis partly because of the rigidity of plant cell walls.

SIGNIFICANCE OF

MITOSIS

In plants

◦ # It is responsible for growth of leaves, stem, roots etc.

◦ # helps in overall development of plant.

◦ # Here centrioles are absent.

In animals

◦ # It helps in growth and repair of cells.

◦ # It gives rise to new identical cells in place of old worn out cells.

◦ # It undergo open mitosis.

◦ # It also leads to change in shape of cell.