1. Chapter 12: The Cell Cycle
AP Biology
Chapter 12:
The Cell Cycle

2. Checkpoints (Is all going according to plan?)

3. Relative concentration. M G1 S G2 M G1 S G2 M
MPF activity
Cyclin
Relative concentration
Time
Fluctuation of MPF activity and cyclin concentration
during the cell cycle

4. Molecular mechanisms that help regulate the cell cycle. G1
Cyclin S
Cdk
Degraded
cyclin M G2
accumulation G2
checkpoint
Cdk
Cyclin is
degraded
Cyclin
MPF
Molecular mechanisms that help regulate the cell cycle

5. Chromosome movement Kinetochore Tubulin subunits Motor Microtubule.
Chromosome
movement
Kinetochore
Tubulin
subunits
Motor
protein
Microtubule
Chromosome

6. Cells anchor to dish surface and divide (anchorage dependence).
When cells have formed a complete
single layer, they stop dividing
(density-dependent inhibition).
If some cells are scraped away, the
remaining cells divide to fill the gap and
then stop (density-dependent inhibition).
25 µm
Normal mammalian cells

7. Cancer cells do not exhibit anchorage dependence .
Cancer cells do not exhibit
anchorage dependence
or density-dependent inhibition.
25 µm
Cancer cells

8. Malignant cancer cells from the breast (See the ABNORMAL “crab” shape of the cells.)

9. Mutations and Cancer MUTATION Cell cycle-stimulating pathway NUCLEUS
Growth
factor
MUTATION
Hyperactive
Ras protein
(product of
oncogene)
issues signals
on its own
G protein
Cell cycle-stimulating
pathway
Receptor
Protein kinases
(phosphorylation
cascade)
NUCLEUS
Transcription
factor (activator)
DNA
Gene expression
Protein that
stimulates
the cell cycle
Cell cycle-inhibiting
pathway
Protein kinases
MUTATION
Defective or
missing
transcription
factor, such as
p53, cannot
activate
Active
form
of p53 UV
light
DNA damage
in genome
DNA
Protein that
inhibits
the cell cycle

10. Question: Lectins are naturally occurring plant proteins that help promote increased mitosis within plant root tips. These proteins influence the normal production of MPF within the root cells and thereby speed up the cell cycle. In no more than three sentences, state ONE similarity and TWO differences between Lectin influenced cells and cancer cells. (5 Points)

11. Scoring Rubric: 1pt. Discussion of one similiarity
Possible discussion points: Increased cell cycle rate.
Cyclin production rate is altered.
1pt. Discussion of difference number 1
1pt. Discussion of difference number 2
Possible discussion points: Cancer does not respond to checkpoints.
Cancer does not have density dependent.
Cancer does not have anchorage dependence.
Cancer not normal function for cells.
Cancer affects normal cyclin production.
Cancer being caused by carcinogens, etc.
1pt. Correct use of scientific terms.
1pt. Answer has no more than three sentences. (Following Directions.)
This question addresses Essential Knowledge: 2.D.3