Cell Cycle
The cell cycle is series of event in cell which leads division of cell into daughter cell. Cell cycle occurs in four stages (G1, S phase, G2 and Mitotic phase). G1, S phase, and G2 comes under the interphase and they prepare itself for the cell division. S phase is synthesis phase in which the DNA replicates. In Mitotic or M phase the actual cell division starts it is divided in four stages first stage is prophase, second stage is metaphase, third stage is anaphase and the fourth stage of telophase then cell undergo cytokinesis.
Fig: CELL CYCLLE
INTERPHASE
Fig: Inter phase
Interphase consists of three phases: G1 phase, followed by S phase, followed by G2 phase after the completion of interphase Mitotic phase comes which includes the mitosis and cytokinesis and forms two daughter cells. Cell spends its 95% life in the interphase During interphase the cell acquires nutrition for cell division and forms protein and other molecule for the cell division and also DNA replication occurs.
G1 phase :
Gap phase 1 or Growth phase 1 it is the phase between mitosis and initiation of replication of DNA. In this phase the cell DNA do not replicates but this phase is metabolically active and helps in the growth of cell.
S PHASE:
Synthetic phase as name suggest synthesis of DNA so the replication of DNA replicates in this phase suppose the DNA contain is 2N initially the it becomes 4N after replication. But the number of chromosome remains same as in G1 phase if it is 2n then after the replication of DNA the chromosomes remains same always remember only the DNA gets replicated but chromosomes remains same.
G2 PHASE:
Cell prepare itself to go the mitotic phase in this phase there are need of RNA, protein and other macromolecule for the multiplication of cell organelles and the formation of cell division.
M PHASE:
Mitotic phase or M phase it is the phase of equational division means the chromosomes equally divides it means that two progeny are produces having same number of chromosomes. In this phase the actual cell division and nuclear division occurs. There four stages occurs in M phase :
- PROPHASE
- METAPHASE
- ANAPHASE
- TELOPHASE
PROPHASE:
In this stage of mitosis the condensation of chromatin it becomes compact and hence chromosomes begins to appears visible. The chromosome attached by Centromere and it starts moving to the opposite pools of nucleus by separating them self. Again the reassembly of cytoskeleton and forms the mitotic spindle movement of centrosome forms mitotic spindle. Nucleolus disappeared. The nuclei stars breakdown so the production of ribosomes disturbed but nuclear envelope remains attached during this process.
METAPHASE:
Metaphase is the stage of cell cycle in which the condensation of genetic material in chromosomes and they align on an axis called the metaphasic plate, Two sister chromatids of each chromosomes is separated microtubule from both opposite poles.
ANAPHASE:
In this stage of cell cycle two chromatids of each chromosome get separated by the structure called mitotic spindle and they move towards the pole. 
TELOPHASE:
It is the final stage of the mitosis the chromosome begin to decondense and uncoiling and form the chromatin, spindle breakdown, and the reformation of nuclear membrane and nucleoli. The division of cytoplasm for the formation of two daughter cells.
0 Comments