Cell Cycle 6.1 Flashcards
What is the cell cycle?
The cycle that a cell goes through from the cell dividing to the formation of two genetically identical daughter cells.
What are the main phases of the cell cycle?
The interphase and the mitotic phase
Interphase
The phase where the cell is not actively dividing, although it is doing a lot of other things. This is the longest phase
What kind of things happens during interphase?
DNA is being replicated and checked for errors.
Proteins are being synthesised
Mitochondria are growing and dividing.
Chloroplasts are growing and dividing
G1 phase
This is the first growth phase where organelles are being synthesised, proteins are being synthesised and the cell is getting bigger.
S phase
DNA is being replicated
G2 phase
This is the second growth phase, the cell is still getting bigger and energy stores are increasing. DNA is also checked for any errors.
Mitotic Phase
This the period when the cell is dividing. It undergoes mitosis and cytokenesis
Go Phase
This is when the cell will leave the cell cycle, either temporarily or permanently.
Why would a cell enter Go phase
The cell could be differentiated into a specialised cell.
The cell could be damaged and there might be a mistake in the DNA which means it will be put in cell arrest and won’t be replicated.
Could just be an ageing person or a person with a disease.
What are the things needed for the cell to begin replication
Has to have the correct DNA sequence
The chromosomes are in the correct position
That they have grown to the right size
Why are checkpoints used in DNA replication?
They are used to monitor and check between each phase to make sure everything is working correctly before it can move onto the next stage.
G1 checkpoint
This is at the end of the G1 phase before the cell can enter the S phase it must go through this checkpoint. The cell must be the correct size and have no DNA damage, as well as sufficient organelles and proteins. If not it will enter a resting state (Go)
G2 checkpoint
This is the end of the G2 phase before the mitotic phase can begin. It checks if the cell is big enough, if the DNA has been replicated and if there are any errors in it. If it doesn’t match the standards, it will enter Go.
Spindle Assembly Checkpoint
This is the point in the mitotic phase where the chromosomes have been attached to the spindles and mitosis cannot begin until this checkpoint is passed.
