ap biology
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AP Biology. Chapter 12: The Cell Cycle. One cell becoming two. Chromatin vs. Chromosomes appearance within the cell. Fig: 19.4 Coiling up of Chromatin. Somatic cells vs. Germ cells The egg surrounded by sperm. Fig: 12.4 Before and after the S phase. - PowerPoint PPT PresentationTRANSCRIPT
AP Biology
Chapter 12:The Cell Cycle
One cell becoming two
Chromatin vs. Chromosomes appearance within the cell.
Fig: 19.4Coiling up of Chromatin
Somatic cells vs. Germ cellsThe egg surrounded by sperm.
Fig: 12.4Before and after the S phase
Mitosis (1 Division) vs.Meiosis (2 Divisions)
Interphase
Interphase cell (Look at the chromatin in the blue nucleus and the
yellow cytoskeleton.)
Fig: 12.6 a
Cell in Prophase
Fig: 12.6 b
Cell in Metaphase
Cell in Anaphase
Cell in Telophase and starting Cytokinesis
LE 12-8b
Chromosomemovement
Microtubule Motorprotein
Chromosome
Kinetochore
Tubulinsubunits
Animal vs. Plant
LE 12-10
NucleusCell plateChromosomesNucleolus
Chromatincondensing 10 µm
Prophase. The chromatin is condensing.The nucleolus is beginning to disappear.Although not yet visible in the micrograph, the mitotic spindle is starting to form.
Prometaphase. Wenow see discrete chromosomes; each consists of two identical sister chromatids. Laterin prometaphase, the nuclear envelope will fragment.
Metaphase. The spindle is complete, and the chromosomes, attached to microtubules at their kinetochores, are all at the metaphase plate.
Anaphase. The chromatids of each chromosome have separated, and the daughter chromosomes are moving to the ends of the cell as their kinetochore micro- tubules shorten.
Telophase. Daughter nuclei are forming. Meanwhile, cytokinesis has started: The cell plate, which will divide the cytoplasm in two, is growing toward the perimeter of the parent cell.
Microscopic view of Mitosis in Onion root tips.Can you identify the stages?
LE 12-11_3Origin ofreplication
Cell wall
Plasmamembrane
Bacterialchromosome
E. coli cell
Two copiesof origin
Chromosome replication begins. Soon thereafter, one copy of the origin moves rapidly toward the other end of the cell.
Replication continues. One copy of the origin is now at each end of the cell.
Origin Origin
Replication finishes. The plasma membrane grows inward, and new cell wall is deposited.
Two daughtercells result.
Checkpoints(Is all going according to plan?)
LE 12-15
G1
G1 checkpoint
G1
G0
If a cell receives a go-ahead signal at the G1 checkpoint, the cell continues on in the cell cycle.
If a cell does not receive a go-ahead signal at the G1 checkpoint, the cell exits the cell cycle and goes into G0, a nondividing state.
LE 12-16a
MPF activity
G1 G2S MS MG2G1M
Cyclin
TimeFluctuation of MPF activity and cyclin concentrationduring the cell cycle
Rel
ativ
e c o
ncen
t rat
ion
LE 12-16b
Degradedcyclin G2
checkpoint
S
M
G 2G 1
Cdk
Cyclin isdegraded
MPF Cyclin
Cdk
Molecular mechanisms that help regulate the cell cycle
accumulation
Cyclin
LE 12-8b
Chromosomemovement
Microtubule Motorprotein
Chromosome
Kinetochore
Tubulinsubunits
LE 12-18aCells 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
LE 12-18b
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.)