Proteins are essential to most processes in the human body. Given your understanding of the M phase of the life cycle, please discuss two different protein dependent processes associated with this phase. Make sure you provide specific details about the chosen processes.
Cell Cycle and Phases Of Cell Cycle ---- The ordered sequences of events which takes place in the cell going to take part in cell division .Cells divide and grows by taking part in to cell division .
Interphase --Cell during this time grows ,replicate its chromosomes and prepare for cell division . After coping all the DNA and having extra pair of chromosomes, cell moves into G2 phase .
Time Taken During Cell Cycle to complete -- For most of human cell a single cell cycle takes 24 hours to complete and where there is a continuous need of removal and replacement . In the lining of intestine time taken is 9 hours .
Stages --- Cell cycle contains 4 stages
( i )Gap (G1 ) phase ( ii ) S phase synthesis phase ( jjj ) Gap ( G2 ) phase ( iv ) Mitosis ( M ) phase .
Interphase -- G1 , S and G2 phase all are referred as interphase , in which there is growth of cell and replication of its DNA .
In G1 phase -- Cell grows physically and increases the volume of both proteins and organelle , also determines that all conditions are favorable.
In S phase --- Cell copies its DNA to produce two sister chromatids and replicates its nucleosomes for cell division to proceed.
In G2 phase -- There is further cell growths and organization of cellular contents .
Components of proteins in cell cycles --- Cell cycle is controlled by various proteins which act in both stimulate and inhibit cell cycle . Following proteins takes part in cell cycle --
( i )Cyclin-- Most important proteins takes part in stimulation of the cycle .
With the alteration ( synthesis and degradation ) of cell cycle levels at various stages, stimulation of function of Cdks , who can function in presence of cyclins .
Cyclins are synthesized ,act as activating proteins and binds to Cdks forming a cyclin - Cdks complex .
This complex formation is signal to pass to next cell cycle phase .Degradation of cyclins causes deactivating the Cdks signal time to exit from the phase .
Types of Cyclins --Mainly two types of cyclins -- ( i )G1 Cyclins ( ii )Mitotic cyclins
( i ) G1 cyclins-- These proteins bind to Cdks proteins during G1 phase . When it is bounded with Cdks and become activated , Cdks signals the cell to exit from G1 phase and enters in to S phase .
When the cell reaction reaches appropriate size and cellular environment is correct for DNA replication .
When Cyclins begin to degrade . G1 Cyclins degradation deactivates the Cdks and leads to entry in to S phase .
( ii )Mitotic Cyclins -- Mitotic cyclins accumulate gradually during G2 , once high concentration of cyclins is achieved bind to cdks .
Mitotic Cyclins bind to cdks in G2 , resulting complex is called as mitosis - promoting factor ( MRF ) , indicating signals for G2 cell to enter mitosis .
Degradation of mitotic cyclins MPF is inactivated and cell exists mitosis by dividing and re entering G1 phase .
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