Control of the Cell Cycle Flashcards Preview

AP Biology 2014 > Control of the Cell Cycle > Flashcards

Flashcards in Control of the Cell Cycle Deck (14):

Cell Cycle Control System


Cyclical set of molecules that triggers and coordinates main events in the eukaryotic cell cycle.  It makes sure events occur only once, at proper times, and in the correct order.

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Point where stop and go-ahead signals monitor process of cell cycle


(Signal trandsuction pathways launches the signals)


3 Major Checkpoints


G2 Checkpoint

M Checkpoint

(These checkpoints correspond to the 3 phases in the cell cycle)

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What does the G1 Checkpoint check?

1. Cell Size

2. Genetic Material

If the genetic material is NOT damaged.  If it is damaged, then the process is delayed and the genetic material is repaired.  If there is a stop signal, the cell exits and enters G0.


G0 Phase

State in which cells leave the cell cycle and do NOT divide


(Most cells in our bodies are in the G0 phase)


What does the G2 Checkpoint check?

1. Genetic Material Duplication

2. Cell Size

3. Genetic Material Completeness

If damage is detected, chromosomes are repaired




What does the M Checkpoint check?

1. Genetic Material Attachment

If all chromosomes are attached to spindle fibers from both poles


External physical factors that effect cell division

1. Growth Factors

2. Density-dependent Inhibition

3. Anchorage Dependence



Growth Factors

Proteins received in the plasma membrane that stimulate cells to divide


Density-dependent Inhibition

Contact with other cells causes an animal cell to stop dividing


Anchorage Dependence

Requirement that a cell must be attached to a substratum, such as the inside of a culture flask, in order for the cell to divide


Cancer Cells

Cancer cells do not respond to signals that trigger checkpoints in the control system; thus, they grow and divide rapidly. Density-dependent inhibition and anchorage dependence do not effect cancer cells.

(Cancer is a disease of the cell cycle.)




Cyclin-dependent kinases

Proteins that advance cells past checkpoints and through the cycle.

Kinases that phosphorylate other proteins



 Activate Cdks and help control progression from one stage of the cell cycle to the next. After the cell passes a checkpoint, the cyclins are destroyed, and  specific new cyclins for the next checkpoint emerge.