1. AP Biology
The Cell Cycle
Part 1

2. One cell becoming two

3. Binary Fission in Prokaryotes
Cell wall
Origin of
replication
Plasma
membrane
E. coli cell
Bacterial
chromosome
Chromosome replication begins.
Soon thereafter,
one copy of the origin moves rapidly toward the other end of the cell.
Two copies
of origin
Origin
Origin
Replication continues. One copy of the origin is now at each end of the cell.
Replication finishes.
The plasma membrane grows inward, and
new cell wall is deposited.
Two daughter
cells result.

4. Chromatin vs. Chromosomes appearance within the cell.

5. Coiling up of Chromatin using histones

6. Somatic cells vs. Germ cells The egg surrounded by sperm.

7. Sister Chromatids

8. Mitosis (1 Division) vs. Meiosis (2 Divisions)

9. AP Biology
The Cell Cycle
Part 2

10. Centrioles

12. Interphase

13. Before and after the S phase

14. Interphase cell (Look at the chromatin in the blue nucleus and the yellow cytoskeleton.)

15. Start of Mitosis

16. Cell in Prophase

17. Mitosis “Division of the nucleus”

18. Cell in Metaphase

19. Cell in Anaphase

20. Cell in Telophase and starting Cytokinesis

21. One cell becoming two

22. Motor Protein and the Spindle Fibers
Chromosome
movement
Kinetochore
Tubulin
subunits
Motor
protein
Microtubule
Chromosome

23. Animal vs. Plant

24. LE 12-10 Chromatin condensing Nucleus Chromosomes Cell plate 10 µm
Nucleolus
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. We
now see discrete chromosomes; each
consists of two identical sister chromatids. Later
in 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.

25. Microscopic view of Mitosis in Onion root tips
Microscopic view of Mitosis in Onion root tips. Can you identify the stages?

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

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

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

29. 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

30. 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

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

32. 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

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

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

35. 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

36. Cell Communication (Signaling) Part 1
AP Biology
Cell Communication (Signaling)
Part 1

37. Direct Contact

38. Local and Long Distance within an organism.

39. Phermones

40. Earl Sutherland

41. Step 1: Reception

42. Step 2: Transduction

43. Step 3: Response

44. See the CONFORMATION SHAPE CHANGE by the receptor protein caused by the ligand binding.
Signal
molecule
(ligand)
Gate
closed
Ions
Plasma
membrane
Ligand-gated
ion channel receptor
Gate open
Cellular
response
Gate closed

45. Cell Communication (Signaling) Part 2
AP Biology
Cell Communication (Signaling)
Part 2

46. Phosphorylation and Hydrolysis

47. Receptor Protein

48. G protein Receptor

49. Tyrosine – Kinase Receptor

50. Ion Channel Receptors Signal molecule (ligand) Gate closed Ions Plasma
membrane
Ligand-gated
ion channel receptor
Gate open
Cellular
response
Gate closed

51. Intracellular receptors

52. Secondary Messenger cAMP
Adenylyl cyclase
Phosphodiesterase
Pyrophosphate
H2O P P i
ATP
Cyclic AMP
AMP

53. First messenger
(signal molecule
such as epinephrine)
Adenylyl
cyclase
G protein
G-protein-linked
receptor
GTP
ATP
Second
messenger
cAMP
Protein
kinase A
Cellular responses

54. Secondary Messenger Calmodulin
EXTRACELLULAR
FLUID
Signal molecule
(first messenger)
G protein
DAG
GTP
G-protein-linked
receptor
PIP2
Phospholipase C
IP3 (second
messenger)
IP3-gated
calcium channel
Cellular
re-
sponses
Various
proteins
activated
Endoplasmic
reticulum (ER)
Ca2+
Ca2+
(second
messenger)
CYTOSOL

55. Cell Communication (Signaling) Part 3
AP Biology
Cell Communication (Signaling)
Part 3

56. Kinases “turn on” processes Phosphotases “turn off” processes

57. Small signal produces a BIG response

58. The Big picture Growth factor Reception Receptor Phosphorylation
cascade
Transduction
CYTOPLASM
Inactive
transcription
factor
Active
transcription
factor
Response P
DNA
Gene
NUCLEUS
mRNA

59. Scaffolding Proteins Signal Plasma molecule membrane Receptor Three
different
protein
kinases
Scaffolding
protein

60. Tyrosine – Kinase Receptor (Evolution – Change over TIME)