4.5-4.7: Feedback/Cell Cycle Regulation

predict the result of a mutation that allows a cell to move past checkpoint a M even though the chromosomes we're not prepared for division **apoptosis**

-disfunctional cells with wrong copies/#'s of chromosomes **apoptosis**

predict the result of a mutation that allows a cell to move past a checkpoint G1 even though the cell has not grown sufficiently

-may get stopped at G2 or M -may not form properly (too small to survive)

predict the result of a mutation that allows a cell to move past checkpoint G2 even though DNA replication has not been completed

-may get stopped at M -cell wont have proper DNA *apoptosis*

suggest two or more combinations of mutations that would tend to allow the cell cycle to become unregulated

-mutation in eirher above gene and p35 gene (no apoptosis) -change in DNA repair mechanisms and add mutation in either above Gene

would the effects of chemotherapy be seen first in organs that have quickly dividing cells (like intestine and hair follicles) or in organs that have slow or nondividing cells (like muscles and the nervous system)

-quick dividing cells won't divide (cancer. cells are quick dividing) -non dividing cells have no impact -slow dividing cells (probably in G0) so it wont have that not much impact in time

propose an explanation for the change in the maturation promoting factor (MPF) Concentration throughout the cell cycle based on your knowledge of the concentration of Cdk and cyclin

-when there is the most cyclin, there is the most MPF because the more substrate (cyclin) the more the MPF.

negative feedback

A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation.

Homeostasis

A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level

Chromatin

Clusters of DNA, RNA, and proteins in the nucleus of a cell

S

DNA replication occurs

positive feedback

Feedback that tends to magnify a process or increase its output.

what phase of the cell cycle are these cells said to be in when they are not diving or planning to divide?

G0

There is adequate room in the environment for more cells in what checkpoint?

G1

Which checkpoint appears to regulate whether the cell is in G0 or not?

G1

at which checkpoint in the cell cycle would a tumor suppressor Gene check adequate room for more cells?

G1

There is ample supply of energy and raw materials available in what check point?

G1 and G2

which of the phases of the cell cycle fall into the "interphase" time frame?

G1, S, G2

Name the three checkpoints

G1,G2, M

indicate the phase of the cell cycle and what part of the phase (early or later), where each point occurs

G1-->S phase (later) G2--> M phase (later) M--> anaphase (later)

at which checkpoint in the cell cycle would a tumor suppressor Gene repair DANA function?

G2

the DNA has been completely replicated and checked for errors in what checkpoint?

G2

which checkpoint in the cell cycle is regulated by the concentration of MPF?

G2: end of interphase has the highest concentration of MPF

All chromosomes are attached to the spindles in what checkpoint?

M

which checkpoint in the cell cycle is affected by paclitaxel?

M: microtubles are centrioles and spindle fibefs in metaphase and anaphase

G2

The cell prepares for cell division with the appearence of centrosomes

table:

accelerator (proti-oncogenes): regulate cell cycle & allow passing from G2 to cell division brake (tumor suppresor):slows down if its too croded

how does paclitaxel inhibit the growth of cancer?

cell division does not finish

describe the changes in concentration of cyclin as the cell moves through different phases of the cell cycle

high in interphase, low in mitosis

how might a cell be affected by the development of a degradation- resistant cycling mutant?

it cant break cyclin, MPF would always be active and might skip checkpoints

M

mitosis and cytokinesis occurs

can the change in cyclin concentration during mitosis be explained by the fact that the cell divides in two and thus divides the material in the cell into two smaller volume?

no, cyclin concentration goes down as its used up

Chromatid

one half of a duplicated chromosome

describe the changes in the concentration of cycle dependent kinase (cdk) as the cell moves through different phases of the cell cycle

stays the same

if cycling was always available in the cell at high concentrations, what effect would this have on the cell cycle?

the cell cycle would continue unchecked fhrouvh mitosis withoug using the checkpoint

G1

the cell grows by producing more proteins and organelles

Chromosomes

threadlike structures made of DNA molecules that contain the genes