1. Cell Division
• All cells come from cells!
• Why do cells divide?
– Repair and growth - Mitosis
– Reproduction – Meiosis
• Two kinds of reproduction:
– Asexual
– Sexual

2. Which cell division is for growth and
repair?
A) Mitosis
B) Meiosis

3. Asexual Reproduction
• Asexual reproduction – An organism
duplicates its genetic material then splits into
two cells
• All offspring are genetically identical to each
other and the parent
• Ex: paramecium, hydra and sea stars

5. Sexual Reproduction
• Sexual reproduction – Genetic material from 2
parents combine
• Offspring are genetically unique (different
from parents)
• ½ of the genetic material comes from each
parent

6. Offsprings that are genetically
identical to their parents are
products of
A) Asexual reproduction
B) Sexual reproduction

7. DNA
• When a cell divides the genetic material in the
original cell is passed to the new cells
• DNA is the genetic material of all living organisms
• DNA appears as either chromatin or
chromosomes.
• DNA appears as chromatin during normal cell
activity.
• During cell division (mitosis and meiosis) DNA
forms structures called chromosomes.

8. Chromosomes
• Chromosomes are small condensed packages
that are easily moved around by the dividing
cell.

9. Chromosome Structure
• The two strands of a single chromosome are
called sister chromatids.
• They are connected by a structure called a
centromere.
• Sister chromatids are identical sequences of
DNA
Sister
chromatids
Centromere

10. Chromatin
The structure of
chromatin is
similar to a
bowl of
spaghetti.

11. Chromatin and Chromosomes

12. True or False
DNA can take the form of chromatin or
chromosome.

13. The black arrows are pointing at…
A) Centromere
B) Chromosome
C) Sister chromatids
D) Chromatin

14. The red box is…
A) Centromere
B) Chromosome
C) Sister chromatids
D) Chromatin

15. Stages of the Cell Cycle
• The cell cycle is composed of interphase and the
mitosis
G’s stand for gaps. M
stands for mitosis. S
stands for synthesis.
The G phases seemed
to be gaps in cell activity
during the cell cycle.

16. Interphase
• Interphase is in general a time of normal cell
activity. Cells carry out their normal metabolic
processes and perform their usual functions.
• DNA appears as chromatin in interphase.
• Interphase is composed of 3 stages:
– G1, S and G2.

17. Interphase
• G1: Cell grows
• S: DNA replicates
(synthesized)
• G2: Cell prepares
to divide

18. Interphase
• During late G2 two centrosomes appear outside
the nucleus.
• Spindle microtubules extend from the
centrosomes and connect to chromosomes.
• Microtubules move chromosomes around
during mitosis

19. S- phase
• DNA replicates itself
• This is done to provide each daughter cell a
complete set of DNA

20. During interphase…
A) The cell stops its normal functions
B) DNA replicates
C) The cell divides
D) The cell prepares to divide
E) Both B and D

21. M phase
• M phase is composed of mitosis and
cytokinesis
• A parent cell divides into 2 daughter cells
• Mitosis is composed of four stages
• Prophase, metaphase, anaphase and
telophase (PMAT)
• Cytokinesis is when the cytoplasm actually
divides into 2 new cells.

23. M Phase is:
A) part of interphase
B) when the cell does normal cell activity
C) mitosis and cytokinesis
D) only mitosis

24. Prophase
• Nucleus disappears
• Chromatin condenses into chromosomes
• Centrosomes migrate to opposite poles(ends) of the
cell.
• Spindle microtubules form
– They will eventually attach to the centromere of each
chromosome

26. Metaphase
• Chromosomes move to the middle of the cell
(metaphase plate)
• Microtubules pull chromosomes apart.
Anaphase

28. Telophase
• Nucleus reforms
• Chromosomes unwind into chromatin
• Microtubules disappear
• Centrosomes migrate near nucleus
• Telophase is the opposite of prophase!

30. Chromosomes line up in the middle
of the cell at which phase?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase

31. Sister chromatids are pulled apart
at which phase?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase

32. True or False
Microtubules disappear at Telophase.

33. Cytokinesis
• The actual division of the cytoplasm.
• Usually occurs with telophase, but may start
during anaphase.
• The first sign in animal cells is the indentation
around the middle of the cell.
• In plants, a cell plate forms inside the cell.
• The cell plate contains new cell wall material.

35. Plant Cytokinesis

36. True or False
Plant cytokinesis also occurs with the
indentation around the middle of the cell.

40. Cancer
• Cancer is caused by severe disruption of the
mechanisms that normally control the cell
cycle.
• This disruption leads to uncontrolled cell
division.

41. Cancer
• Benign tumor – an abnormal mass of
essentially normal cells.
• Cells remain at their original site.
• Can cause health problems depending on their
location, but can usually be completely
removed by surgery.

42. Cancer
• Malignant tumors – mass of cells resulting
from the reproduction of cancer cells.
• Malignant tumors displace normal tissue as
they grow.
• They are characterized by their ability to
rapidly spread.
• Metastasis – spread of cancer beyond its
original site.

43. Cancer

44. • Treatment involves surgery, radiation therapy
and/or chemotherapy.

45. Cancer involves
A) Treatment through surgery, radiation
therapy, and/or chemotherapy
B) Malignant tumors displacing normal
tissue
C) Severe disruption of the cell cycle
D) All of the above
E) None of the above