Block 2 Lecture 9 : The Cell Cycle & Cancer Flashcards
During which specific phase does the cell duplicate organelles and cytostolic components
G1 phase of Interphase
during which phase does the cell replicate DNA and centrosomes
S phase of interphase
during which phase are enzymes and other proteins synthesised
G2 phase
which phase: nuclear envelope breaks down, nucleolus dissolves, mitotic spindle connects to kinetochores
prometaphase
during which phase does the centromere split, with chromatids being dragged to either centrosome
anaphase
which phase: chromatin condenses into chromosomes and mitotic spindle starts to form
prophase
which phase: microtubules align chromosomes on metaphase plate
metaphase
which phase: chromosomes revert to chromatin, nuclear envelope reforms, nucleolus reappears, mitotic spindle breaks down
telophase
what is the name of the ring that pinches the plasma membrane during cytokinesis to separate the two cells?
actin-myosin ring
what is an example of a cell cycle regulatory molecule and how does it act to regulate the cell cycle
MPF, mitosis promoting factor, induces mitosis
what are the two polypeptide subunits of an MPF?
CDK protein kinase, cyclin
what is the function of CDK
cyclin dependent kinase catalyses the phosphorylation of a target protein by ATP
how do the concentrations of CDK and cyclin vary during the cell cycle
CDK remains much the same, cyclin concentration increases during interphase, peaks during Mitosis and then decreases
because of the dependency of a CDK on _____, the levels of phosphorylation of the CDK and hence the activity of the MPF and hence the incidence of mitosis are controlled by ______
cyclin
is MPF activated when cyclin is phosphorylated or unphosphorylated
unphosphorylated cyclin is the activated form
what are three things that an activated MPF phosphorylates in order to kickstart mitosis
phosphorylates: chromosomal proteins to initiate the M phase, lamins to initiate nuclear envelope degradation, microtubules to initiate mitotic spindle
MPF activates a protein which catalyses the _____ of the MPF cyclin
degradation
MPF is disassembled when ____________ polyubiquitinates cyclin B/ CDK1
APC, anaphase promoting complex
when does cyclin degradation begin
shortly after the beginning of anaphase
what is the mechanism that degrades MPF
negative feedback
In our bodies, without effective _________, cells will keep growing and form a tumour
cell cycle checkpoints
protooncogenes normally function by promoting appropriate progression through the cell cycle. However they can be mutated rendering them active, a ______
oncogene
This mutated oncogene will produce a hyperactive _____, which gives its own cell growth signals
Ras protein
The Ras protein will result in the ______ of a protein that stimulates the cell cycle
transcription
Tumour supressor proteins ____ cell division but when mutated may lose this ability
inhibit
tumour suppressor protein mutation occurs when there is a defective or missing form of transcription factor _____, so transcription of the inhibits protein does not continue
p53
APC degrades MPF therefore is a _____ gene
tumour supressor
name the three stages of tumour growth from smallest to largest
polyp - adenoma - carcinoma
which of the three stages of tumour growth is malignant?
carcinoma
what is metastatic cancer
cancer that has spread via the blood or nymph to other parts of the body
