2.4 1bio

Question 1

what are the happens during interphase ?

Answer 1

-This is period of no cell division ,the cell increases in mass and size and replicate their DNA ready for cell division .

Question 2

what are the phases for the cell cycle

Answer 2

G1 ,S,G2,Mitosis ,Cytokinesis

Question 3

what happens during g1 phase

Answer 3

Its the start of chromosmal duplication .The cell assimlates material ,grows ,develops .In actively dividing cells the G1 phase is very short .

Question 4

what happens during the s stage of the cell cycle

Answer 4

The chromosomes replicate and become double stranded chromatids ready for the next cell division

Question 5

what happens during the G2 phase of the cell cycle

Answer 5

The organelles and materials needed for the cell division are sythesised (everything is duplicated)

Question 6

what is the cell cycle controlled by

Answer 6

a number of chemical signals made in response to different genes .

Question 7

what are checkpoints and why are they important in controlling the cell division

Answer 7

The control chemicals are small proteins called cyclins ,these build up and attach to enzymes called cyclin dependent kinases

Question 8

what are cyclin dependent kinases

Answer 8

They are complexes that is formed phosphorylates other proteins chaning their shape and bringing about the next stage of the cycle

Question 9

what are histones

Answer 9

they are positively charged proteins involved int eh coiling of DNA to form dense chromsosmes in cell division