Guaranteed Pass Solutions.
What happens during G1? - Answer First growth phase; cell synthesizes proteins and produces
cytoplasmic organelles
What happens during the S phase? - Answer Synthesis; continues to grow as it copies chromosomes
What happens during G2? - Answer Second growth phase; cell completes preparation needed to divide
and continues basic life of the cell
What happens during mitosis? - Answer Subdivided into prophase, metaphase, anaphase, and
telophase; nuclear division
What happens during cytokinesis? - Answer Process of splitting the daughter cells apart; splitting of
cytoplasm and allocation of the organelles and cytoplasm into each new cell
How does the number of chromosomes compare between G1 and G2? - Answer Remains the same
How does the amount of DNA compare between G1 and G2? - Answer G2 has double the amount of
DNA (after S phase where chromosomes are duplicated)
What is the outcome of mitosis and why is this important? - Answer 2 diploid daughter cells; creates
more cells, regeneration, replenishes old cells when they die; essential for growth and repair in the body
What is the difference between a kinetochore microtubule and a non-kinetochore microtubule? -
Answer Kinetochore microtubules attach to the kinetochore of chromosomes whereas non-
kinetochore don't
What is the function of a kinetochore microtubule during mitosis? - Answer Where the spindle fibers
attach during division to pull chromosomes apart
,What is the function of a non-kinetochore microtubule during mitosis? - Answer Responsible for
elongation of cell during anaphase
Cytokinesis in animal cells - Answer Formation of a cleavage furrow which gradually "pinches" the cell
in half
Cytokinesis in plant cells - Answer Formation of cell plate that gradually divides the cell in half -
eventually thickens to form new cell wall
Why is cytokinesis different in plants and animals? - Answer Plant cells have cell walls which are
inflexible and cannot be "pinched in"
In an experiment, you fuse two cells, making 1 large cell with 2 nuclei. At the time of fusion, Cell 1 had
been in mitosis and Cell 2 had been in the G1 phase. Predict what will happen to each of the nuclei for
Cell 1 and for Cell 2 after they have fused. - Answer Cell 2 nucleus will immediately enter mitosis
because the cell cycle is driven by specific signaling molecules present in the cytoplasm and Cell 1 would
continue with mitosis
What is the link between cyclins and MPF? - Answer Cyclin is a regulatory protein that a kinase must be
attached to; MPF is made up of cyclin combined with a CDK (cyclin-dependent kinase)
On a molecular level, what does a MPF molecule do? - Answer "Maturating-promoting factor;" Triggers
the cell's passage past the G2 checkpoint into the M phase (accumulation of cyclin proteins combined
with CDK to form MPF)
When during the cell cycle does production of cyclin really increase? - Answer Accumulated during G1
and S phase; increased during G2 prior to M phase (needs to make enough MPF to pass G2 checkpoint
and enter M phase)
What impact does a high concentration of MPF have on a cell? - Answer Triggers onset of mitosis;
reduced at end of mitosis because it depends on cyclin concentration
, Interphase - Answer Contains G1, S, and G2 phase; chromosomes are not visible (instead in form of
chromatin), make a copy of themselves
Prophase - Answer Copies of chromosomes fasten together; nuclear membrane disappears; chromatin
condenses into chromosomes; centrosomes are pushed apart to opposite ends of the cell nucleus by
action of molecular motors acting on microtubules
Metaphase - Answer Chromosomes line up along the center metaphase plate; microtubules have
found and attached to kinetochores; centromeres convene themselves on metaphase plate equidistant
from 2 centrosome poles
Anaphase - Answer Chromosomes split apart and are pulled to opposite ends of the cell; break at
centromeres and sister chromatids move to opposite ends
Telophase - Answer Chromosomes become hard to see (unwind into chromatin); cells splits and 2
nuclear membranes form (2 daughter cells); nuclei reappear
List 4 external requirements for a cell to get past the G1 checkpoint - Answer (1) appropriate size
(2) adequate energy reserves (enough nucleotides to duplicate DNA)
(3) no DNA damage
(4) favorable environment
What are some ways in which a cell could divide even in the absence of the normally required growth
factor? - Answer Cancer cells, for example, can have defective cell cycle control systems and proceed
past the checkpoints even in this absence; can divide indefinitely
Imagine a scenario in which a point mutation occurs in the gene for a cell cycle protein allowing the cell
to ignore the requirements to pass the G1 checkpoint. What would be a likely outcome for the cell and
surrounding tissue? - Answer Cancer cells (abnormal growth and division)
Difference between benign and malignant tumor - Answer Benign: abnormal cells may remain at
original site if they have too few genetic and cellular changes to survive at another site