The Cell Cycle
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29 Terms
What is the cell cycle?
A highly ordered sequence of events that takes place in a cell.
What does the cell cycle results in?
The division of the cell and the formation of of two genetically identical cells.
What type of cells does the cell cycle occur in?
Eukaryotic cells.
What are the two main phases of thr cell cylce in eukaryotes?
Interphase and the mitotic phase.
What are the three stages of interphase?
G1, S and G2
What happens in G1?
The first growth phase: the cell grows in size and organelles (except the nucleus) are duplicated.
What happens in the S stage?
DNA is replicated in the nucleus.
What happens in G2?
The second growth phase: the cell continues to increase in size, energy stores are increased. The cell checks the DNA for any errors and makes any repairs. The cell prepares for division.
What is the mitotic phase?
The period of cell division.
What does the mitotic phase include?
Mitosis - where the nucleus divides.
Cytokinesis - where the cytoplasm divides and two cells are produced.
What is meant by G0?
It is the phase when the cell leaves the cycle, either temporarily or permanently. A resting state.
What are some reasons why a cell might enter G0?
Differentiation.
DNA damage.
Cell aging.
Why does a cell undergoing differentiation enter G0?
A cell that becomes specialised to carry out a particular function is no longer able to divide, it will carry out this function indefinetely and not enter the cell cycle again.
Why does a cell with DNA damage enter G0?
The DNA of a cell may be damaged, in whhich case is is no longer viable. A damaged cell can no longer divide so it enters G0. The majority of cells only divide a limited number of times and eventually become sensent.
Why do aging cells enter G0?
AS you age, the number of these (sensent) cells in your body increases. Growing numbers of sensent cells have been linked with many age related siseases, such as cancer and arthiritis.
What are the control mechanisms of the cell cycle?
Checkpoints.
What do checkpoints do?
They monitor and verify whether the processes at each phase of the cell cycle have been accurately completed nefore the cell is allowed to progress into the next phase.
When does the G1 checkpoint occur?
At the end of the G1 phase.
What does the G1 checkpoint check for?
Cell size.
Nutrients.
Growth factors.
DNA damage.
What happens if the G1 checkpoint passes?
DNA replication starts.
What happens if the G1 checkpoint fails?
The cell goes into G0 as DNA damage woud lead to disfunctional proteins and smaller cells.
When does the G2 checkpoint occur?
At the end of the G2 phase.
What does the G2 checkpoint check for?
Cell size.
DNA replication.
DNA damage.
What happens if the G2 checkpoint passes?
Mitosis begins.
What happens if the G2 checkpoint fails?
The cell goes into G0 as DNA damage woud lead to disfunctional proteins and smaller cells.
When does the spindle assembly checkpoint occur?
During metaphase (mitosis): when the chromosomes are attached to spindles and have aligned,
What does the spindle assembly checkpoint check for?
If the chromosomes are attached to spindles.
If the chromosomes are aligned.
What happens if the spindle assembly checkpoint passes?
Mitosis proceeds.
What happens if the spindle assembly checkpoint fails?
Mitosis would be paused.