6.1 (2.1.6) The cell cycle

define cell cycle

a highly ordered sequence of events that takes place in a cell, resulting in division of the cell, and the formation of two genetically identical daughter cells

describe steps of G1

1) the cell checks that the chemicals needed for replication are present and for any damage to the DNA before entering S phase

2) cellular contents (excluding chromosomes) are replicated

3) cell increases in size

describe steps of S phase

DNA is replicated in the nucleus

describe steps of G2

1) cell checks that all DNA has been replicated without errors

2) cell continues to increase in size

3) energy stores are increased

why do some cells undergo G0

1) a differentiated cell is no longer able to divide so it will carry out this function indefinitely and not enter the cell cycle again

2) the DNA of the cell is damaged and no longer viable

define G0

permanent cell arrest

define checkpoints

the control mechanisms of the cell cycle

what does G1 checkpoint check for

cell size, nutrients, growth factors, DNA damage

what does G2 checkpoint check for

cell size, DNA replication, DNA damage

what does spindle assembly checkpoint check for

chromosome attachment to spindle

where in the cell cycle is G1 checkpoint

end of G1 before entry into S

when in the cell cycle is G2 checkpoint

end of G2 before start of mitosis

when in the cell cycle is spindle assembly checkpoint

metaphase