Cell Reproduction: Mitosis and Cancer
February 6, 2002

Readings: Starr Ch. 12, 196-197, Ch. 8, 126-133, and Essay 8.6 (p 135)
CD-ROM: excellent diagrams and a cool mitosis movie!
Don't Forget! This week's WarmUp is due TODAY at 9:30!

"To understand the things that are at our door is the best preparation for understanding those things that lie beyond"- Hypatia, c. 370-415

I. Cell Division: How does one cell become two cells?

Life is based on the ability of cells to reproduce,

• For multicellular organisms (
  • Somatic Cells: (Mitosis, today)
  • Germ Cells: (Meiosis, Monday)
• For one-celled organisms, c
  

II. The Cell Cycle: How does the cell spend its time?

Phases of the Cell Cycle

G1	G
S	S
G2	G
M	M

 

Some terms:
Chromosomes:

Humans have 23 pairs of chromosomes,

Diploid:

Haploid:

 

 

III. Mitosis: how 1 cell divides into 2 identical cells

CObviously, some SERIOUS organizational skills are needed to make sure this process runs smoothly......

Overview: Before DNA Replication (S Phase) - one chromosome

After DNA Replication (but before mitosis) - a duplicated chromosome, made up of 2 sister chromatids

VI. DNA replication - a closer look

DNA before replication: 1 double helix

DNA after replication: 2 identical double helixes

The DNA double helix is perfectly suited for replication because each strand can serve as a template (mold) to produce a shape opposite to itself.

A cast of enzymes and proteins accomplish DNA replication:

1.

2.

3.

4.

5.

6.

V. Stages of Mitosis: How 1 cell becomes 2

The overall process:

VI. Cancer cells escape the controls on cell division:

1. What is cancer?

2. Tumors - Good Cells gone Bad...?

Benign:

Malignant: t

So, why do chemotherapy drugs cause a person's hair to fall out? See this week's WarmUp!

3. Unusual features of Cancer Cells.

(1) Cancer cells are frequently "immortal":

(2) Cancer cells often have unusual numbers

(3) Cancer cells may also have an abnormal cell surface

(4) Cancer cells ignore the usual density-dependent inhibition of growth

Objectives: After this lecture, your should be able to:

1. Draw or describe the phases of the cell cycle (and what happens in each)

2. Describe a chromosome and contrast it with a sister chromatid.

a. How did it get to BE a sister chromatid?

b. Why do the sister chromatids stay joined together?

3. Explain how DNA is 'unzipped' and replicated. What is the function of DNA helicase, DNA ligase, DNA polymerase, and DNA repair enzymes? What do Histone proteins do?
4. Draw and describe each phase of mitosis (you will see this again, hint hint...)

5. Describe how a normal cell can be transformed into a cancer cell

6. Explain the 4 unusual features of cancer cells.