Cell Cycle Regulation and Cancer. Flashcards
Define cytokinesis?
The point of mitosis where the cytoplasm is divided, forming 2 identical daughter cells.
Define a kinase enzyme?
An enzyme which phosphorylates proteins.
Define meiosis?
A type of cell division that results in the formation of 4 haploid gametes.
Define mitosis?
Cell division that occurs in somatic cells and results in the formation of 2 daughter cells from 1 parent cell.
Define a phosphatase enzyme?
An enzyme that de-phosphorylates proteins.
Define a quiescent cell?
A cell that is not dividing but has the ability to divide.
Define a somatic cell?
Any cell within the body that is not a reproductive cell.
Define a transcription factor?
A protein that is involved in transcription.
What is the cell cycle defined as?
The time taken between 2 cell divisions.
What are the 3 primary stages that make up the cell cycle?
Interphase.
Mitosis.
Cytokinesis.
What are the 4 stages of mitosis?
Prophase.
Metaphase.
Anaphase.
Telophase.
What is cytokinesis?
The point of the cell cycle where the dividing cell is cleaved into 2 daughter cells.
How many pairs of chromosomes are found in a cell?
23 pairs.
The cell cycle is the time that is taken between waht 2 events?
The cell cycle is the time that elapses between the formation of cell and the division of the same cell.
What kind of cells are produced by mitosis?
Somatic cells.
What kind of cell division produces sex cells or gametes?
Meiosis.
What is the end product of meiosis?
4 non-identical daughter cells, all of which are haploid.
How is a diploid cell created from a haploid gamete?
A fertilisation, the zygote that is created by the union of egg and sperm will be diploid.
This is because it receives half its chromosomes from the mother and half from the father.
What is the major difference between mitosis and meiosis?
Mitosis results in the formation somatic cells and meiosis result the formation of gametes.
In meiosis chromosomes take part in step known as synapsis.
What is synapsis that occurs during meiosis?
Where the homologous chromosomes pair up and form tetrads.
Does synapsis and crossing over occur in mitosis?
No.
When does crossing over occur during meiosis?
During synapsis.
What is crossing over?
Where genetic information is exchanged between chromosomes.
How many cycles of cell division take place during meiosis?
2 separate cycles of cell division.
What happens during the first division of meiosis?
2 diploid cells are formed.
What happens during the second division of meiosis?
4 haploid cells are formed.
How many cell divisions occur in mitosis?
1.
What are the mitotic phase and cytokinesis collectively known as?
M phase.
What phase is the majority of the cell cycle dominated by?
Interphase.
What are the 3 sub-phases that interphase is divided into?
G1 phase (first growth phase).
S phase (synthesis phase).
G2 phase (second growth phase).
What is the main characterisitc of interphase?
The cell will grow much larger in size.
Does cellular growth occur in any particular stage of interphase?
Growth occurs in all 3 phases.
What happens in G1 phase of interphase?
The centrioles will replicate.
What happens in S phase of interphase?
The DNA will replicate.
What happens in G2 phase of interphase?
The final growth before meiosis occurs.
What is the only point in mitosis where DNA will be replicated.
S phase of interphase.
What are cell cycle checkpoints used for?
To ensure that cellular replication occurs properly.
What will cell cycle checkpoints mainly search for?
For mutations within DNA replication and to ensure that the cellular machinery is been correctly assembled.
What disease could DNA mutations lead to?
Cancer.
Is the the cell cycle regulated by intrinsic or extrinsic control mechanisms?
It is regulated by both internal and external control mechanisms.
Can the cell cycle stop part way through the cell cycle?
Yes, the cell cycle can stop at a particular checkpoint until a go-ahead signal is received.
What are the 4 checkpoints that are found in the cell cycle?
G1/S checkpoint.
G2/M checkpoint.
M checkpoint.
G0 quiescence.
What happens at the G1/S checkpoint?
The cell checks to see if the environment is favourable for division and it will monitor the size and integrity of DNA.
What happens if DNA is damaged during the G1/S checpoint?
Apoptosis will occur.
What happens at the G2/M checkpoint?
The cell monitors DNA replication and checks for any damage or mistakes in the newly synthesised DNA.
What happens at the M checkpoint?
The cell monitors the formation of the spindle and the attachment of the spindle to the kinetochores.
What happens during mitosis if the chromosomes are not properly aligned on the metaphase plate?
Then mitosis will not happen.
What is the G0 or quiescence checkpoint?
The G0 quiescence makes the final decision as to whether to exit the cell cycle or to start again.
Which scientists discovered the cell cycle in 2001?
Lee Hartwell.
Paul Nurse.
Tim Hunt.
What was Hartwells contribution to the discovery of the cell cycle?
He used budding yeast to to identify the various mutants that blocked the cell cycle.
What are cyclins and cyclin dependent kinase’s (CDK’s)?
A group of regulatory proteins that help to regulate the cell cycle.
What are cyclins?
Independent proteins.
What are CDKs?
Kinase enzymes which depend on cyclin proteins.
When does the intracellular concentrations of cyclin proteins tend to increase?
At the end of each stage of the cell cycle.
When will CDK enzymes be present in the cell?
They are always present in the cell.
What activates CDK enzymes?
The increase in cyclin proteins in the cell activates CDK’s and once activated they will bind to the cyclin proteins.
What is the complex that is created by the binding of the CDKs to the cyclin proteins known as?
The MPF (maturation promoting factor).
What happens as the cellular concentration of MPF rises?
It will trigger cell division to go on to the next stage.
What happens to MPF complexes after the cell cycle has moved on to the next stage?
The cyclin proteins are degraded until the next checkpoint where cyclin concentration will rise again.
What kind of cyclins bind to CDK’s at the end of G1/S phase?
They will bind to G1/S cyclins.