1. Copyright Pearson Prentice Hall
Prentice Hall Biology
Copyright Pearson Prentice Hall

2. Copyright Pearson Prentice Hall
10-2 Cell Division
Photo Credit: © CAMR/A.B. Dowsett/Science Photo Library/Photo Researchers, Inc.
Copyright Pearson Prentice Hall

3. Copyright Pearson Prentice Hall
The Cell Cycle
During the cell cycle:
a cell grows
prepares for division
divides to form two daughter cells, each of which begins the cycle again
Copyright Pearson Prentice Hall

4. Copyright Pearson Prentice Hall
The Cell Cycle
Cell Cycle
The cell cycle is the series of events that cells go through as they grow and divide.
Interphase is the period of growth that occurs between cell divisions.
Copyright Pearson Prentice Hall

5. Copyright Pearson Prentice Hall
The Cell Cycle
The cell cycle consists of four phases:
G1 (First Gap Phase)
S Phase
G2 (Second Gap Phase)
M Phase
G0 Phase (Resting
phase)
Copyright Pearson Prentice Hall

6. Events of the Cell Cycle
During G1, the cell
increases in size
synthesizes new proteins and organelles
Copyright Pearson Prentice Hall

7. Events of the Cell Cycle
During the S phase,
chromosomes are replicated
DNA synthesis takes place
Once a cell enters the S phase, it usually completes the rest of the cell cycle.
Copyright Pearson Prentice Hall

8. Copyright Pearson Prentice Hall
Cell Division
DNA to Chromatin to Chromosomes
Copyright Pearson Prentice Hall

9. Copyright Pearson Prentice Hall
Chromatin: consists of DNA tightly coiled around proteins called histones
Copyright Pearson Prentice Hall

10. Chromosomes
Chromosomes
Genetic information is passed from one generation to the next on chromosomes.
Before cell division, each chromosome is duplicated, or copied.

11. Copyright Pearson Prentice Hall
Chromosomes
Each chromosome consists of two identical “sister” chromatids.
Each pair of chromatids is attached at an area called the centromere.
Sister chromatids
Photo Credit: © Gunther F. Bahr/AFIP/Stone
Centromere
Copyright Pearson Prentice Hall

12. Copyright Pearson Prentice Hall
Chromosomes
DNA
Copyright Pearson Prentice Hall

13. Events of the Cell Cycle
The G2 Phase (Second Gap Phase)
Preparing for Cell Division
organelles and molecules required for cell division are produced
Once G2 is complete, the cell is ready to start the M phase—Mitosis
Copyright Pearson Prentice Hall

14. Events of the Cell Cycle
During the cell cycle, the cell grows, replicates its DNA, and divides into two daughter cells. DNA synthesis takes place during the S phase. Cell division takes place during the M phase. G1 and G2 are gap phases.
Copyright Pearson Prentice Hall

15. Copyright Pearson Prentice Hall
Cell Division
In eukaryotes, cell division occurs in two major stages.
The first stage, division of the cell nucleus, is called mitosis.
The second stage, division of the cell cytoplasm, is called cytokinesis.
Copyright Pearson Prentice Hall

16. Copyright Pearson Prentice Hall
Chromosomes
When the cell divides, the chromatids separate.
Each new cell gets one chromatid.
Copyright Pearson Prentice Hall

17. Copyright Pearson Prentice Hall
Mitosis
Mitosis
Biologists divide the events of mitosis into four phases: (PMAT)
Prophase
Metaphase
Anaphase
Telophase
Copyright Pearson Prentice Hall

18. Copyright Pearson Prentice Hall
Mitosis
Most eukaryotic cells go through a regular cycle of interphase, mitosis and cytokinesis. Mitosis has four phases: Prophase, Metaphase, Anaphase and Telophase. The events shown here are typical of animal cells.
Mitosis
Copyright Pearson Prentice Hall

19. Chromosomes (paired chromatids)
Mitosis
Section 10-2
Spindle forming
Prophase
Prophase
Chromosomes (paired chromatids)
Centromere
Most eukaryotic cells go through a regular cycle of interphase, mitosis and cytokinesis. Mitosis has four phases: Prophase, Metaphase, Anaphase and Telophase. The events shown here are typical of animal cells.
Click to Continue
Copyright Pearson Prentice Hall

20. Copyright Pearson Prentice Hall
Mitosis
Spindle
forming
Prophase
Prophase is the first and longest phase of mitosis.
The centrioles separate and take up positions on opposite sides of the nucleus.
Centromere
Chromosomes
(paired chromatids)
Copyright Pearson Prentice Hall

21. Copyright Pearson Prentice Hall
Mitosis
Spindle
forming
The spindle is forming and the pairs chromosomes are visible.
The centrosome helps to organize the spindle, a fanlike microtubule structure that helps separate the chromosomes.
Centromere
Chromosomes
(paired chromatids)
Copyright Pearson Prentice Hall

22. Copyright Pearson Prentice Hall
Mitosis
Spindle
forming
Chromatin condenses into chromosomes.
The centrioles separate and a spindle begins to form.
The nuclear envelope breaks down.
Centromere
Chromosomes
(paired chromatids)
Copyright Pearson Prentice Hall

23. Copyright Pearson Prentice Hall
Mitosis
Metaphase
Centriole
Spindle
Centriole
Metaphase
Click to Continue
Copyright Pearson Prentice Hall

24. Copyright Pearson Prentice Hall
Mitosis
Centriole
Metaphase
The second phase of mitosis is metaphase.
The chromosomes line up across the center of the cell.
Microtubules connect the centromere of each chromosome to the poles of the spindle.
Spindle
Copyright Pearson Prentice Hall

25. Individual chromosomes
Mitosis
Anaphase
Individual chromosomes
Anaphase
Copyright Pearson Prentice Hall

26. Copyright Pearson Prentice Hall
Mitosis
Anaphase
Anaphase is the third phase of mitosis.
The sister chromatids separate into individual chromosomes.
The chromosomes continue to move until they have separated into two groups.
Individual
chromosomes
Copyright Pearson Prentice Hall

27. Nuclear envelope reforming
Mitosis
Telophase
Nuclear envelope reforming
Telophase
Copyright Pearson Prentice Hall

28. Copyright Pearson Prentice Hall
Mitosis
Telophase
Telophase is the fourth and final phase of mitosis.
Chromosomes gather at opposite ends of the cell and lose their distinct shape.
Copyright Pearson Prentice Hall

29. Copyright Pearson Prentice Hall
Mitosis
A new nuclear envelope forms around each cluster of chromosomes.
Copyright Pearson Prentice Hall

30. Copyright Pearson Prentice Hall
Cytokinesis
Cytokinesis
Cytokinesis
Copyright Pearson Prentice Hall

31. Copyright Pearson Prentice Hall
Cytokinesis
During cytokinesis, the cytoplasm pinches in half.
Each daughter cell has an identical set of duplicate chromosomes
Copyright Pearson Prentice Hall

32. Copyright Pearson Prentice Hall
Cytokinesis in Plants
In plants, a structure known as the cell plate forms midway between the divided nuclei.
Cell plate
Cell wall
Copyright Pearson Prentice Hall

33. Copyright Pearson Prentice Hall
The G0 Phase (resting phase)
The cell leaves the cell cycle and quits dividing.
This may be a temporary resting period or more permanent.
Ex: Nerve cells and heart muscle cells no longer divide after reaching maturity.
Copyright Pearson Prentice Hall

34. Copyright Pearson Prentice Hall
10-2
- or -
(must have QuickTake software installed on the computer you are using for this presentation)
Copyright Pearson Prentice Hall

35. Copyright Pearson Prentice Hall
10-2
The series of events that cells go through as they grow and divide is called
the cell cycle.
mitosis.
interphase.
cytokinesis.
Copyright Pearson Prentice Hall

36. Copyright Pearson Prentice Hall
10-2
The phase of mitosis during which the chromosomes line up across the center of the cell is
prophase.
metaphase.
anaphase.
telophase.
Copyright Pearson Prentice Hall

37. Copyright Pearson Prentice Hall
10-2
Cytokinesis usually occurs
at the same time as telophase.
after telophase.
during interphase.
during anaphase
Copyright Pearson Prentice Hall

38. Copyright Pearson Prentice Hall
10-2
DNA replication takes place during the
S phase of the cell cycle.
G1 phase of the cell cycle.
G2 phase of the cell cycle.
M phase of the cell cycle.
Copyright Pearson Prentice Hall

39. Copyright Pearson Prentice Hall
10-2
During mitosis, “sister” chromatids separate from one another during
telophase.
interphase.
anaphase.
metaphase.
Copyright Pearson Prentice Hall

40. END OF SECTION