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what are the four essential functions of the cell cycle?
1) to copy and pass on its genetic information to the next generation of cells, 2) to produce 2 genetically indentical daughter cells, where the DNa in each chromosome is accurately replicated, 3) the replicated chromosomes must be correctly segregated into the two daughter cells so that each receives a copy of the entire genome, and 4) ordinarily, cells must also duplicate their organelles and macro-molecules.
what are the names of the 4 phases involved in mitosis?
Prophase, Metaphase, Anaphase, Telophase
what key event occurs during cytokinesis?
the cytoplasm and its contents separate in two
which phase, G1, G2, S, or M, is cytokinesis a part of?
M phase
what are the 3 phases which compose interphase?
G1, S, G2
during which part of interphase is the DNA replicated in preparation for M phase?
S phase (synthesis)
the length of G1 is proportional to what in most cells?
the rate of cell division
what is the name of the quiescent phase that cells can opt into if they do not have the resources or proper environment for M phase?
G0 phase.
for which kinds of cells is G0 phase a permanent state?
skeletal muscle and nerve cells
what is morphogenesis?
how organisms acquire their unique shape.
what does cdk stand for? upon the presence of which proteins is the activation of cdk's dependent?
cyclin-dependent kinase; cyclins
what action do cdk's perform in initiate certain events in the cell cycle?
phosphorylation of key proteins.
what are the names of the two major cdk's and by which cyclins are they each controlled?
mitotic cdk and s-phase cdk; m-cyclin and s-cyclin
which, cdk's or cyclins, are always present in the cell?
cdk's
how does the positive feedback work with cdk-cyclin complexes?
each activiated cyclin-cdk complex will activate more of the same complex in a geometric fashion.
how are cyclins destroyed after they have performed their job?
by being tagged with ubiquitin and being fed to proteosomes.
for what does MPF stand?
maturation promoting factor
what are 4 events triggered by M-cyclin?
1) chromatin condensation, 2) nuclear envelope breakdown, 3) fragmentation of Golgi and ER, and 4) spindle formation.
what are the 3 categories of extracellular signal molecules?
1) mitogens, 2) growth factors, and 3) survival factors
what is the role of mitogens?
stimulate cell division
what is the role of growth factors?
to stimulate cell growth and increase cell mass
what is the role of survival factors?
to promote cell survival by suppressing apoptosis
what events characterize interphase?
cell growth, replication of DNA, duplication of the centrosome and centrioles
what events characterize prophase?
condensation of chromatin into mitotic chromosomes, and initial growth of the mitotic spindle apparatus.
which are the 3 categories of microtubules compose the spindle apparatus?
1)polar, 2)astral, and 3)kinetochore
what is the role of dynein and kinesin
microtubule motors
which events characterize prometaphase?
breakdown of nuclear envelope, attachment of spindle microtubules to kinetochores on chromosomes
what events characterize metaphase?
chromosomes arranged in equitorial plane, spindle completed, disappearance of nuclear envelope and nucleolus
what events characterize early anaphase?
longitudinal spilitting of chromatids and migration to poles
what events characterize late anaphase?
aggregation of chromosomes at the poles, beginning of cell division, intiation of cleavage furrow
what events characterize telophase?
nuclear restitution, nuclear envelope and nucleolar formation, end of cell division
which end, + or -, is anchored to the centrosome during mitosis? and which type of microtubules are responsible for this anchoring?
-; gamma tubules
what does it mean to say the free end of the microtubules in the spindles are 'dynamically unstable'?
they are rapidly growing and simultaneously shrinking.
when 2 microtubules from spindles overlap in the overlap zone, which proteins are responsible for cross-linking the two microtubules?
motor proteins (kinesin and dynein) and other microtubule-associated proteins.
what is the point of connecting overlapping spindles?
to stabilize the + end by decreasing probability of their depolymerization
during which 2 phases of mitosis are chromosomal abnormalities most likely to take place?
prophase, metaphase
what are deletions in terms of chromosomal abnormalities?
when a part of a chromosome is missing, or part of the DNA genome is missing
what are inversions in terms of chromosomal abnormalities?
when a chromosome breaks and a piece reverses and reattaches itself
what are duplications in terms of chromosomal abnormalities?
when part of a chromosome is present in 2 copies
what are nondisjunctions in terms of chromosomal abnormalities?
an error in cell division where the chromosomes fail to separate, so that both pass to the same daughter cell - this results in monsomy and trisomy)
what are translocations in terms of chromosomal abnormalities?
when a location of a specific chromosome material attaches to another chromosome
what is trisomy 21?
when 3 copies of chromosome 21 result -- Down's syndrome
what is the karyotype of a cell?
the number and visual appearance of chromosomes in the nuclei.
the presence of what in interphase cells is useful in determining the sex of an individual?
Barr bodies
which family of proteases mediate most of the apoptosis that occurs in the human body?
caspases
what is necrosis?
unintentional cell death that requires the action of lymphocytes and a consequent immune response (swelling)
what is apoptosis?
organized, intentional cell death that also requires lymphocytes but since the death is planned, there is no immune response.
what kind of protein is responsible for dephosphorylation?
phosphorylase
where are the 3 major checkpoints in the cell cycle?
G1, G2, M
what questions are asked at G1 checkpoint?
DNA damage?
Favorable environment to grow?
what questions are asked at G2 checkpoint?
DNA damage?
Is cell big enough for division?
what questions are asked at M checkpoint? when does M checkpoint occur?
are all chromosomes aligned properly on metaphase plate?; metaphase
in which checkpoint does p53 play a role? what does it do?
G1; monitors DNA for damage
what events does p53 trigger to stop cell cycle?
regulates transcription of p21 gene. p21 protein binds to s-cyclin-cdk complex and makes repairs before cell can continue
what are cohesins and condensins?
proteins that package the chromosomes for mitosis.
what is another term for the centrosome?
MTOC
what shape relative to each other do centrioles take up?
right angle
of what is a centriole composed
9 triplets of alpha-beta tubulin
where do chromosomes attach to spindles?
at kinetochores
nuclear envelope disappearance in mitosis is related to what event?
phosphorylation of lamins by m-cdk
at what point on the cell is the kinetochore located?
centromere
which enzyme is involved in telomere shortening?
telomerase
in which role are cohesins especially important?
keeping sister chromatids together.
for what does APC stand?
anaphase promoting complex
what does APC do?
triggers a proteosome to destroy cohesins and triggers the separation of sister chromatids
of what is the contractile ring in cytokinesis composed?
actin, myosin, and other proteins.
what is the name for the invaginating area between 2 cells in cytokinesis?
cleavage furrow
what is amniocentesis?
when cells are taken from fetal fluid to determine genetic birth defects, etc.