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AP Biology. Chapter 12: The Cell Cycle. Checkpoints (Is all going according to plan?). G 1. S. G 2. G 1. M. M. M. S. G 2. MPF activity. Cyclin. Relative concentration. Time. Fluctuation of MPF activity and cyclin concentration during the cell cycle. G 1. Cyclin. S. Cdk. M. - PowerPoint PPT Presentation
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AP Biology
Chapter 12:The Cell Cycle
Checkpoints(Is all going according to plan?)
.
MPF activity
G1 G2S MS MG2G1
M
Cyclin
Time
Fluctuation of MPF activity and cyclin concentrationduring the cell cycle
Rel
ativ
e co
nce
ntr
atio
n
.
Degradedcyclin
G2
checkpoint
S
M
G 2G 1
Cdk
Cyclin isdegraded
MPFCyclin
Cdk
Molecular mechanisms that help regulate the cell cycle
accum
ulatio
nC
yclin
.
Chromosomemovement
Microtubule Motorprotein
Chromosome
Kinetochore
Tubulinsubunits
.Cells anchor to dish surface anddivide (anchorage dependence).
When cells have formed a completesingle layer, they stop dividing(density-dependent inhibition).
If some cells are scraped away, theremaining cells divide to fill the gap andthen stop (density-dependent inhibition).
25 µmNormal mammalian cells
.
Cancer cells do not exhibitanchorage dependenceor density-dependent inhibition.
Cancer cells25 µm
Malignant cancer cells from the breast(See the ABNORMAL “crab” shape of the cells.)
Mutations and Cancer
Activeformof p53
DNADNA damagein genome
UVlight
Protein kinasesMUTATION
Defective ormissingtranscriptionfactor, such as p53, cannotactivatetranscription
Protein kinases(phosphorylationcascade)
Cell cycle-inhibitingpathway
Cell cycle-stimulatingpathway
Protein thatstimulatesthe cell cycle
NUCLEUS
DNA
Gene expression
Transcriptionfactor (activator)
Receptor
G protein
Growthfactor
MUTATIONHyperactiveRas protein(product ofoncogene)issues signalson its own
Protein thatinhibitsthe cell cycle
• 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)
•
• 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