Unit 1: Protein control of cell division Flashcards
(25 cards)
Describe the function of the cytoskeleton?
The cytoskeleton provides mechanical support and shape to cells
Describe the function of microtubules?
Microtubules control the movement of membrane-bound organelles and
chromosomes
Microtubules also form the spindle fibres that are active during cell division
What type of cells are present in cytoskeleton?
Eukaryotic cells
What are the two parts of the cell cycle?
Interphase
Mitotic phase
Describe the three sub-phases within the interphase in the cell cycle?
G1:This is a growth period where proteins and organelles are synthesised
S:This is where the cell continues to grow and where DNA replication occurs
G2: this is another growth period
Describe the two sub-phases within the mitotic phase in the cell cycle?
Mitosis: the chromosomal material is separated by the spindle microtubules
Cytokinesis: The separation of the cytoplasm into two daughter cells
Describe the 4 stages of mitosis?
Prophase: The DNA condenses into chromosomes with each consisting of two sister chromatids. Spindle microtubules attach to chromosomes via their kinetochore in the centromere.
Metaphase: chromosomes are aligned across the metaphase plate
Anaphase: spindle microtubules shorten and sister chromatids are separated and chromosomes are pulled to opposite poles of the cell
Telophase: Chromosomes decondense and nuclear membranes form around each of the two daughter cells.
Describe the function of cyclin-CDK’s?
They phosphorylate proteins that regulate progression in the cell cycle. In G1 this phosphorylation inhibits Rb protein allowing the cell cycle to progress.
Describe the function of Retinoblastoma?
retinoblastoma protein (Rb) acts as a tumour suppressor by
inhibiting the transcription of genes that code for proteins needed for DNA replication
At which stages are there checkpoints in the cell cycle?
G1, G2, M
Describe the G1 checkpoint and what proteins regulate it?
If there is sufficient phosphorylation by G1 cyclin-CDK’s, the cell cycle moves onto the next stage, if there isn’t then the cell is held at the checkpoint
Describe the G2 checkpoint?
At this checkpoint the success of DNA replication is assessed and any damage to DNA is assessed
What does DNA damage trigger?
DNA damage triggers the activation of several proteins including p53 that can stimulate DNA repair, arrest the cell cycle or initiate apoptosis
Describe the metaphase checkpoint?
At the metaphase checkpoint, progression is halted until the chromosomes are aligned correctly on the metaphase plate and attached to the spindle microtubules.
What can cause a degenerative disease?
An uncontrolled decrease in the rate of the cell cycle
What can cause a tumour to form?
An uncontrolled increase in the rate of the cell cycle
What is a proto-oncogene?
A proto-oncogene is a normal gene, usually involved in the control of cell growth or division, which can mutate to form a tumour-promoting oncogene
What types of cell death signals are there that can trigger apoptosis (programmed cell death)?
Apoptosis is triggered by cell death signals that can be external or internal
What’s an example of an external death signal?
The production of death signal molecules from lymphocytes is an example of an external death signal.
Whats an example of an internal death signal?
DNA damage is an example of an internal death signal.
Describe the function of external death signals?
External death signal molecules bind to a surface receptor protein and trigger a protein cascade within the cytoplasm
Describe the function of internal death signals?
An internal death signal resulting from DNA damage causes activation of p53 tumour-suppressor protein
What do both types of death signals result in?
Both types of death signal result in the activation of caspases (types of protease enzyme) that cause the destruction of the cell
Why is apoptosis necessary?
Apoptosis is essential during development of an organism to remove cells no longer required as development progresses or during metamorphosis. for example cells between fingers of animals.
