1. Bellwork
Domestic horses have 64 chromosomes. How many chromosomes should be in an egg cell of a female horse? A. 16 B. 32 C. 64 D. 128

2. Agenda 12/4- Cell Cycle, Division (Mitosis)
Bellwork
Lab: DNA extraction from strawberries
New Information: Cell Cycle, Mitosis
Homework: Identifying Stages of the Cell Cycle- virtual lab

3. DNA Extraction Lab We’ll read through the lab procedure together.
You can use this same procedure to extract DNA from any living thing (including your own DNA!)
Safety is critical! No gum, no food, no drinks. Always assume chemicals are dangerous! (even though these are relatively safe if you don’t consume them).

4. Bellwork 12/7 What are the 4 phases of the cell cycle?
What are the 4 phases of mitosis?
What phases are shown below?

5. Agenda 12/7- Cell Cycle and Mitosis
Bellwork
New Information: Cell Cycle and Mitotic Cell Division (mitosis)
Lab/Activity: start cell cycle and mitosis lab- drawings

6. Cell Cycle and Cell Division (Mitosis)
What is mitosis? Why is it important?

7. Cell Division 3 reasons for mitotic cell division (mitosis):
Growth
Repair
Replacement
Parent cell divides into two identical daughter cells

8. Cell Division
Cells divide to make new cells- DNA is replicated so each daughter cell gets an exact copy.
DNA condenses into chromosomes during mitosis. 8

9. Cell Division Humans have 46 chromosomes, 23 from each parent.
Haploid cells: only one of each chromosome (n)
Diploid cells: two of each chromosome (2n)

10. Cell Cycle (click for video clip)
G1 phase
M phase
S phase
G2 phase

11. Interphase- longest G1 Phase Cell growth S Phase DNA replication
preparation for mitosis
M Phase
mitosis and cytokinesis
Allium G1
M phase S G2

12. Interphase Nucleus and nuclear envelope are visible.
One or more nucleoli are visible.
The rest of the nucleus is filled with chromatin.

13. Figure 10-5 Prophase Interphase Cytokinesis Metaphase Telophase
Anaphase

14. Prophase pro- = first; first stage of mitosis
Nuclear envelope breaks down
Chromatin condenses into chromosomes
Centrioles move to opposite poles of the cell
Spindle fibers attach to chromosomes at the centromere.
(plant cells have microtubule organizing centers instead of centrioles)

15. Metaphase Chromosome line up in the Middle of the cell
Chromosome centromeres are attached to the spindle at the poles of the cell

16. Anaphase
Chromosome centromeres separate and sister chromatids move Apart to the opposite ends of the cell

17. Telophase Chromosomes precipitate back into strands of DNA (chromatin)
A new nuclear envelope begins to form around each of the two new clumps of DNA

18. Cytokinesis Same time as Telophase Animal Cells:
(“cell splitting”)
Same time as Telophase
Animal Cells:
cytoplasm splits as the cell membrane draws inward (cleavage furrow) and splits the cell in two
Plant Cells:
cytoplasm splits as a cell plate forms between the two new nuclei, then a new cell membrane

19. Cell Cycle and Mitosis I P M A T C I Protect Mothers And Their
Children
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

20. Cell Cycle and Mitosis Virtual Lab
Go to
Make a table like the one you’ll see before the activity begins.
Answer the following questions:
Which phase of the cell cycle is longest? How do you know? Which is shortest, and how do you know?

21. Agenda 12/8- Cell Cycle and Cancer
Bellwork
Notes- Cell Cycle Control and Cancer
Lab- Mitosis in Onion Root Tip Cells
HW- finish lab questions, study for test (Thurs)- DNA structure and replication, cell cycle, and mitosis

22. Binary Fission
Prokaryotes (bacteria) reproduce by a type of cell division called binary fission.
In binary fission the single bacterial chromosome replicates and the two daughter chromosomes actively move apart.

23. G1 phase
M phase
S phase
G2 phase

24. The Cell Cycle Control System
The events of the cell cycle are directed by a cell cycle control system, similar to a clock.
Figure 12.14
Control system
G2 checkpoint
M checkpoint
G1 checkpoint G1 S G2 M

25. The Cell Cycle Control System
There are specific checkpoints where the cell cycle stops until a go-ahead signal is received.
G1 checkpoint G1 G0
(a) If a cell receives a go-ahead signal at the G1 checkpoint, the cell continues on in the cell cycle.
(b) If a cell does not receive a go-ahead signal at the G1checkpoint, the cell exits the cell cycle and goes into G0, a non-dividing state.
Figure A, B

26. Control of Cell Division
In density-dependent inhibition crowded cells stop dividing.
Most animal cells also exhibit anchorage dependence in which they must be attached to a substratum to divide.
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).
Normal mammalian cells. The availability of nutrients, growth factors, and a substratum for attachment limits cell density to a single layer.
(a)
25 µm
Figure A

27. Control of Cell Division
Cancer cells: no density-dependent inhibition or anchorage dependence.
Do not respond normally to the body’s control mechanisms and form tumors.
Loss of the cell cycle controls.
25 µm
Cancer cells do not exhibit anchorage dependence or density-dependent inhibition.
Cancer cells. Cancer cells usually continue to divide well beyond a single layer, forming a clump of overlapping cells.
(b)
Figure B

28. Control of Cell Division
Malignant tumors invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body where they may form secondary tumors.

29. Cancer Risk Factors Quiz

30. Lab Objectives
To list the phases of the cell cycle in the order in which they occur.
To list the phases of the M-phase of the cell cycle (Mitosis) and explain what happens during each.
To illustrate/draw what happens during each phase of Mitosis.
To identify the role of cell structures during cell division (centrioles, chromatin, chromosomes, nucleus).
To learn the importance of cell division for organisms (asexual reproduction, growth, repair).

31. Mitosis in Allium Root
Interphase
Prophase
Metaphase

32. Mitosis in Allium Root
Anaphase
Telophase

34. Prophase
Interphase
Metaphase
Telophase
Anaphase

35. Eukaryotic Cell Division
Mitosis- normal cell division
Parent cell divides into two identical daughter cells (diploid = 2n)
n = number of types of chromosomes
Meiosis- cell division resulting in reproductive cells (gametes)
Parent cell divides into 4 daughter cells, each with half the number of chromosomes (haploid = 1n)

36. Agenda 12/9- Sexual vs. Asexual Reproduction
Discuss lab, finish
New information: Sexual vs. Asexual Reproduction
Activity: Cell Cycle, Mitosis Review Worksheet
Quiz tomorrow, Cancer Brochure Research Project due Monday

37. Agenda 12/11- Cell Division and Reproduction
Bellwork- none
Types of Cell Division and Reproduction
Pros/Cons of Sexual vs. Asexual Reproduction
Video- Life’s Greatest Miracle

38. Mitosis
2 diploid daughter cells formed, just like parent cell (two of each chromosome)
Preceded by interphase (G1, S, G2 phase)
Mitosis:
Prophase
Metaphase
Anaphase
Telophase

39. Figure 10-5 Prophase Interphase Cytokinesis Metaphase Telophase
Anaphase

40. Why don’t you look exactly like your parents or siblings?
A different form of cell division: Meiosis!
Sexual reproduction increases genetic variation in a population, which increases a species’ ability to adapt to changes in their environment.

41. Sexual Reproduction
Male gamete (sperm) and female gamete (egg) are haploid (1n)
Fertilization occurs when an egg and a sperm fuse to form a zygote (2n).
Meiosis is the form of cell division that results in gametes.

42. Meiosis occurs in somatic cells to produce reproductive cells
4 haploid daughter cells formed (only one of each chromosome)
Preceded by interphase and DNA replication
Two Divisions:
Meiosis I
Meiosis II

43. Why Sex? The Evolution of Sexual Reproduction
offspring are a combination of parents
introduces variety in population
Asexual Reproduction
offspring are identical to parents
little variety in population

44. The Evolution of Sexual Reproduction

45. The Red Queen Hypothesis The Evolution of Sexual Reproduction
The leading hypothesis for why sexual reproduction has persisted
Refers to Lewis Carroll’s Through the Looking Glass
The Red Queen says to Alice:
“It takes all the running you can do, to stay in the same place.”

46. The Red Queen Hypothesis The Evolution of Sexual Reproduction
As species that live at each other's expense co-evolve, they are engaged in a constant evolutionary struggle for a survival advantage. They need "all the running they can do" because the landscape around them is constantly changing. (predator/prey, disease/host)
In other words, hosts change the locks, and parasites, etc invent new keys.
Sexual reproduction is necessary to fight disease, avoid predation, get food, etc.

47. Why Sex? Advantages and Disadvantages of Asexual Reproduction
Pass on all of your genes
No mating behavior costs (don’t have to spend time or energy looking for a mate, no energy wasted on showy displays)
Disadvantages:
Little or no variation
More susceptible to parasites, viruses, etc.
Sexual Reproduction
Advantages:
Variation
More rapid rate of adaptation in a changing environment
Disadvantages:
Costs of mating behavior: competition, no mating
Only pass on half your genes

48. Costs of Sexual Reproduction: Displays, Competition for Mates

49. Life’s Greatest Miracle
Video with worksheet.
Answer all questions- classwork grade.