2.6.1- The Cell Cycle And Its Regulation Flashcards
Define interphase.
Phase of cell cycle where the cell is not dividing; it is subdivided into growth and synthesis phases.
Define ‘mitosis’.
Type of nuclear division that produces daughter cells generically identical to each other and to the parent cell.
Define ‘cytokinesis’.
Cytoplasmic division that follows nuclear division, resulting in two new daughter cells.
What is apoptosis?
Programmed cell death.
What is senescence?
Where the cell can no longer divide.
To reproduce cells, what do cells do in simple terms?
They duplicate and split into two daughter cells.
Mitosis is a type of _________ _________.
Nuclear division.
Mitosis is made up of what two general parts?
Nuclear division and cytokinesis (cytoplasmic division).
Between phases of mitosis is what?
Interphase.
What is generally happening in interphase as a whole?
Elaborate preparations are born made for cell division- it is a carefully controlled and ordered sequence of events with checkpoints.
List in order the stages of the cell cycle.
Gap1- G1 phase (GapO- G0 phase) S Phase- Synthesis Gap2- G2 Phase Mitosis
What are the two main checkpoints in the cell cycle, in interphase?
The G1/S phase- also known as the restriction point. G2/M checkpoint.
Aside from the two main checkpoints in the cell cycle, what are two other, less dominant checkpoints?
Early G1 and halfway through mitosis.
What are the four purposes of the checkpoints in the cell cycle?
- ensure the cell cycle can’t be reversed
- prevent uncontrolled division that could cause tumours
- ensure DNA’s only duplicated once in each cycle
- detect and repair any damage caused to the DNA
At the M phase of the cell cycle, list the three events that take place in the cell.
- cell growth stopped
- cytokinesis
- nuclear division that’s split into four stages- prophase/ metaphase/ anaphase/ telophase
At the G0 phase of the cell cycle, what are the two events that the place within the cell?
- cells undergo apoptosis/ senescence/ differentiation
* some cells stay in the G0 phase for a v long time or indefinitely- eg neurones
List the five events that take place inside the cell at the gap1- G1 phase of the cell cycle.
- organelles duplicate
- cells grow and increase in size
- transcription of genes to make RNA
- P53 tumour suppressor gene controls the phase
- biosynthesis (eg protein synthesis) incl making enzymes needed for DNA replication in the S phase
The P53 gene is a ________ _________.
Tumour suppressor.
The P53 gene controls which phase of the cell cycle?
The G1 phase.
The G1 phase is also known as what?
The growth phase.
The synthesis phase is a _______ phase.
Rapid.
Explain why the S phase of the cell cycle is a rapid phase.
The DNA bad pairs are more susceptible to mutagenic agents, so the fast speed reduces the chances of spontaneous mutations.
What is the event that takes place in the cell during the S Phase of the cell cycle?
*DNA replication
Once in the S phase, the cell is committed to what?
Completing the cell cycle.
When is the cell committed to completing the cell cycle?
Once it has entered the S phase.
In the S phase, explain the result when all the chromosomes are duplicated.
Each duplicated chromosome consists of a pair is identical sister chromatids.
What event takes place in the cell at the G2 phase?
The cell grows.
In the M phase, what does the checkpoint chemical trigger?
The condensation of the chromatin.
Explain the checkpoint that takes place in the M phase of the cell cycle.
Half way through the M phase, the metaphase checkpoint ensures the cell is ready to complete mitosis.
Some cells do not have what phase of the cell cycle?
The G0 phase.
Give an example of a cell that doesn’t have the G0 phase.
The epithelial cells that line the gut.
The G0 phase is a ________ _________.
Resting phase.
How does a cell enter the G0 phase?
It is triggered by a checkpoint chemical during early G1 phase at the restriction point.
Explain the G1 phases checkpoint function.
The checkpoint control mechanism ensures the cell is ready to enter the S phase of the cell cycle and to begin DNA synthesis.
Explain the checkpoint that is in the G2 phase of the cell cycle.
Special chemicals ensure the cell is ready for mitosis by stimulating proteins that will be involved in making the chromosomes condense and the spindles form.
Give a reason as to why every DNA molecule is replicated in the S Phase of the cell cycle.
Crates the chromosomes are u would and the DNA Is diffuse.
What is a housekeeping gene?
A gene that’s active in all types of cells.
In the S phase, there is a specific sequence for the gene replication- explain what that is.
Housekeeping genes are duplicated first and genes that are normally inactive in specific cell types are replicated last.
