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35 Cards in this Set

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what does the process of propagation consist of?
growth and division
what is mitosis?
a process of cell division
what is interphase?
the interval of quiet growth between mitoses
what is the cell cycle?
progression through mitosos, interphase, mitosis, interphase, etc
how long is mitosis typically? what is the range?
24hrs normally
can be 8min-1year
which stage of the cycle does the cell spend most of it's time in?
interphase
what happens during interphase?
the cell duplicates organelles, grows, and prepares for division
what is the S phase?
when the cell duplicates its chromosomes and synthesizes new DNA
where is G2?
after S, before M
where is G1?
before S
where are most of the cell's normal functions carried out?
G1
what phase do cells enter when they are no longer actively dividing?
G-zero
at which stage is a cell considered "committed" to division?
once it has entered S phase
what happens at the G1 checkpoint?
determines whether of not contidions are right before entering S
what happens at the G2 checkpoint?
determines whether DNA, centrioles, etc are duplicated and ready for mitosis
is there a checkpoint in metaphase?
yes- to determine whether the chromosomes are lined up on the metaphase plate before entering anaphase
which checkpoint has been most heavily studied?
G2
what is MPF?
M-phase Promoting Factor
what are the subunits of MPF?
CDK (cyclin dependent kinase) and Cyclin
what is CDK?
an enzyme that phosphorylates other enzymes or proteins involved in mitosis and thus regulates their activities
what is cyclin?
the regulator of CDK
binds to CDK to activate it
what are the normal concentrations of CDK and cyclin in the cell?
CDK- present at concentrations
cyclin- concentrations vary throughout the cycle, peaks at G2 and then drops off
how powerful is MPF?
very... if injected into a cell it will divide even if it not ready to
how is proliferation regulated?
by a number of environmental factors including food availability
what is density-dependent inhibition of cell division?
when a certin density is reached cells will stop dividing... due to GF's or nutrients not available
what is cancer?
uncontrolled cell proliferation that cause an imbalance among an individual's cell population, which can lead to premature death
in a microenvironment, what is essential for cell division?
GF's
what happens if a GF is mutated?
start dividing without stimulation, divide in excess
what are oncogenes?
mutated genes that lead to uncontrolled growth
what are protooncogenes?
normal, unmutated versions of oncogenes
what is the role of oncogenes and protooncogenes?
involved in stimulating and regulating the cell cycle
what are growth inhibitory factors?
factors that act on cells to slow or stop cell division
what is another name for growth inhibitory factors?
tumor-supressor genes
what are tumor supressor genes?
their products act to stop cell division and thereby supress tumor growth
what is the result of a mutation of tumor supressor genes?
wild cell growth or the inability for a cell to replace cells that are lost... depends on the type of mutation