Protein control of cell division Flashcards
What is the role of the cytoskeleton
It gives mechanical support and shape to cells
What does the cytoskeleton consist of
Different protein structures including microtubules
What are microtubules made of and where do they radiate from
Tubulin
The centrosome
What do microtubules do
Control the movement of membrane-bound organelles and chromosomes
What form the spindle fibres that are active during cell division
Microtubules
What does interphase involve and name the phases
Growth and DNA synthesis
G1: growth
S phase: DNA is replicated
G2: further growth
What phase makes up mitosis and cytokinesis
The mitotic (M) phase
Describe prophase
DNA condenses into chromosomes
Nuclear membrane breaks down and spindle microtubules extend from centrosome and attach to chromosomes via their kinetochores
What is a kinetochore
the region of centrosome that the spindle microtubules attach to
What is metaphase
chromosomes align at the metaphase plate
What is anaphase
spindle microtubules separate by depolymerisation
sister chromatids are separated, chromsomes are pulled to opposite poles
What is telophase
chromosomes decondense and nuclear membranes are formed around them
What is the purpose of checkpoints
Assess the condition of the cell during the cell cycle and halt profession to next phase until requirements are met
What is the role of cyclins
They combine with CDK’s which phosphorylate proteins that regulate progression through the cycle. Progression is dependent on sufficient phosphorylation
What the role of retinoblastoma protein in G1
Acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for DNA replication
What is the role of the p53 protein
It responds to DNA damage by stimulating DNA repair, arresting the cell cycle or causing cell death
What phase is the p53 protein produced/when is this checkpoint
G2
Describe the metaphase checkpoint
Progression is halted until chromosomes are aligned correctly on the metaphase plate and chromosomes are attached properly to the spindle microtubules
What is the cause of a degenerative disease
An uncontrolled reduction in the rate of the cell cycle
What could be the cause of a tumour?
An uncontrolled increase in the rate of the cell cycle
What is a proto-oncogene
a normal gene which can mutate to form a tumour promoting oncogene
Name an example of apoptosis caused by external death signals
in response to death signal molecules from lymphocytes
Name an example of apoptosis caused by internal death signals
in response to DNA damage
what causes external death signal apoptosis
death signal binds to surface receptor protein, protein cascade within cytoplasm
what causes internal death signal apoptosis
DNA damage causes the activation of the p53 protein
How does apoptosis work
Activation of capsizes that cause destruction of the cell
When might cells initiate apoptosis
in the absence of growth factors
