2. CYCLE
CELL

3. Cell division results in two new cells identical to the original cell
The original cell is called the parent cell.

4. Chromosomes – Rod-shaped structures that contain DNA and proteins
Chromosomes become darkly-colored when stained
Chromosomes carry the genetic material that is copied and passed from generation to generation of cells.
What is an example of genetic material???

5. Supercoil within chromosome
The structure of eukaryotic chromosomes
Sister chromatids
Centromere
Supercoil within chromosome
Chromosome
Continued coiling within supercoil
Histone (protein)
DNA
Section 8.2 Summary – pages

6. The DNA (chromatin) wraps tightly around proteins called histones.
Purpose? Histones help maintain the shape of the chromosome.

7. Chromosomes consist of two identical halves
Chromosomes consist of two identical halves. Each half is called a chromatid.
Centromere – attachment point of the 2 chromatids

8. Each species has a certain number of chromosomes in each cell.
For example, humans have 46 chromosomes in each cell.

10. 2 types of chromosomes
1. Autosomes – all chromosomes that aren’t sex chromosomes. (#)
2. Sex chromosomes – determine the sex of an organism, but can also carry other traits. (Human sex chromosomes are X and Y)
Females normally have 2 X chromosomes
Males normally have 1 X and 1 Y

11. Karyotype: What do you notice about the X and Y?
Each body cell of an organism produced by sexual reproduction has 2 copies of each autosome.
Karyotype:

12. Haploid or diploid?
Haploid – cells that contain only one set of chromosomes. These have half the number of chromosomes found in diploid cells
Ex: sex cells 1n
Diploid – cells that contain 2 chromosome sets.
Ex: body (somatic) cells 2n
* Note: meaning of somatic

13. Cell Division in Prokaryotes
…called binary fission.
The result is new material that is identical to the original cell.

15. Cell division in eukaryotes is called MITOSIS and is part of the larger CELL CYCLE
Cell division is only one phase of the cell cycle. The cell spends the rest of its life in other phases.
The CELL CYCLE refers to the processes of interphase and cell division in eukaryotes

16. Cell Cycle
The majority of a eukaryotic cell’s life is spent in the growth period known as interphase.
In INTERPHASE the cells grow, copy DNA, and prepare for cell division.
eukaryotes

18. Interphase, the busiest phase of the cell cycle, is divided into four parts – three growth parts and one dormant period.
What’s a dormant period?

19. Four Phases of Interphase
G1 – cell growth – cells grow to mature size
S – DNA copied
G2 – preparation for cell division
G0 – dormant period – cells have reached maturity and never divide again
*** Not all cells will go into the G0 phase.

20. Following interphase, a cell enters its period of nuclear division called mitosis.

22. The four phases of mitosis are prophase, metaphase, anaphase, and telophase.

23. Prophase: The first phase of mitosis
During prophase, the chromatin coils to form visible chromosomes.
Spindle fibers
begin to form
Nuclear envelope begins to disappear
Chromosomes are doubled

24. Chromatin – the uncoiled (loosely-packed) DNA in cells NOT undergoing cell division
Sister Chromatids - the two halves of the doubled structure.
Sister chromatids

25. Remember…
Sister chromatids are held together by a structure called a centromere, which plays a role in chromosome movement during mitosis.
Centromere – attachment point of sister chromatids
Centromere

26. More about the Spindle...

27. Explain the terms:
Spindle
mIcrotublues
Centrioles
Kinetochore

28. Prometaphase (step 1.5) Nuclear envelope finishes breaking down
Spindle finishes forming:
Kinetochores
Microtubules
Spindle fibers arrive at poles

29. Metaphase: The second stage of mitosis
During metaphase, the chromosomes line up on the equator of the spindle.
Centromere
Spindle fibers
Sister chromatids

31. Anaphase: The third phase of mitosis
During anaphase, the centromeres split and the sister chromatids are pulled apart to opposite poles of the cell.

33. Telophase: The fourth phase of mitosis
During telophase, two distinct daughter cells can be seen.
Nuclear envelope reappears
Two daughter cells

34. Cytokinesis
Following telophase, the cell’s cytoplasm divides in a process called cytokinesis.
After this, the cells go on to do interphase again.
Cytokinesis differs between plants and animals.
Toward the end of telophase in animal cells, the plasma membrane pinches in along the equator.

35. Cytokinesis – plant vs. animal
Animal Cell - the area of the cell membrane that pinches in and eventually separates the dividing cell into two cells is called the cleavage furrow

36. Cytokinesis – plant vs. animal
Plant cells have a rigid cell wall, so the plasma membrane does not pinch in.
A cell membrane forms around each cell, and new cell walls form on each side of the cell plate until separation is complete.

39. Do you think that cell cycle length can vary or is it always the same?

40. What controls cell division?
A cell spends most of its time in interphase…so how does it know when to move on to cell division?
PROTEINS regulate at certain checkpoints:
G1 – cell growth checkpoint
G2 – DNA synthesis checkpoint
Mitosis checkpoint

41. checkpoints
G1 (cell growth) checkpoint – if the cell has grown enough, proteins initiate the S Phase

42. checkpoints
G2 (DNA synthesis) checkpoint – DNA repair enzymes check the results of the DNA replication. If inspection is passed, cell can proceed to mitosis

43. checkpoints
Mitosis checkpoint – if mitosis has occurred correctly, proteins signal the cell to exit mitosis and re-enter G1.

44. What if a cell fails inspection?
That cell passes into the G0 phase. Most cells that go to this phase stay there permanently.

45. When Control is Lost…
The proteins that regulate cell growth and division are coded for by genes.
Mutations occur and the cell doesn’t function properly
A disruption could lead to cancer – uncontrolled growth of cells

46. How might proteins be connected to cancers?

47. Results of Mitosis
When mitosis is complete, unicellular organisms remain as single cells.
In multicellular organisms, cell growth and reproduction can result in groups of cells that work together as tissue to perform a specific function.

48. Tissues organize in various combinations to form organs that perform more complex roles within the organism.
Multiple organs that work together form an organ system.

49. Let’s watch…
2:47

52. Question 1 A. centromeres B. chromosomes C. genes D. chlorophylls
The stringy, rod-like structures in the cell nucleus that contain DNA are __________.
A. centromeres
B. chromosomes
C. genes
D. chlorophylls
Section 2 Check

53. Question 2 A. prophase C. anaphase B. metaphase D. telophase
Look at the diagram and identify the stage of mitosis that is depicted.
Centromere
Sister chromatids
A. prophase
C. anaphase
B. metaphase
D. telophase

54. Question 3 A. cytokinesis B. telekinesis C. meiosis D. mitosis
What is the process by which a cell's cytoplasm divides?
A. cytokinesis
B. telekinesis
C. meiosis
D. mitosis
Section 2 Check

55. Question 4 A. organ systems B. organs C. tissues D. cell cycles
In multicellular organisms, groups of cells that work together to perform a specific function are called __________.
A. organ systems
B. organs
C. tissues
D. cell cycles

56. Question 5
Magnification of a plant cell reveals centromeres that have split and sister chromatids being pulled to opposite poles of the cell. This cell is in which phase of mitosis?
A. prophase
B. metaphase
C. anaphase
D. telophase
Chapter Assessment

57. Disappearing nuclear envelope
Question 6
Which phase of mitosis is depicted in this diagram?
Spindle Fibers
Doubled chromosome
Disappearing nuclear envelope
A. prophase
C. anaphase
B. metaphase
D. telophase

58. Question 7
What is the term used for the period of the cell cycle represented by the red arrow in this graph?
A. prophase
DNA synthesis and replication
B. metaphase
Centrioles replicate; cell prepares for division
Rapid growth and metabolic activity
C. centrophase
D. interphase
Mitosis
Cytokinesis
Chapter Assessment

59. Question 8
What is the level of organization that is missing in this diagram? ?
Cell
Organ
(muscle cell)
Organ System
Organism
(stomach)
(digestive tissue)
(Florida Panther)
A. mass
C. tissue
B. cluster
D. cycle
Chapter Assessment

60. Question 9 Which structure represents a cell in prophase of mitosis?B C D
A. A
C. C
B. B
D. D
Chapter Assessment