Good morning! Please get a computer and start logging on, andtake out this assignment…..

1. Identify two problems that growth causes for cells and explain how cell division solves those problems.

a. Too many demands on DNAb. Too far to transport important materials.

oxygen

Carbondioxide

oxygen

Carbondioxide

oxygen

Carbondioxide

Cell division makes smaller cells, each with its own DNA.

How is a cell’s DNA like the books in a library?

• DNA is like a book of instructions for a cell.• The bigger the cell, the more demands there will be on the

DNA.• The bigger the town/city, the more demands there will be

for a library book.

InstructionBook (DNA)

What do cells need DNA for….?

to make proteins

• Building materials (muscle, bone, etc.)

• Control what goes in and out of cell membranes

• Control chemical reactions (enzymes)

• Fight infections (antibodies)

2. If a plant cell is 3 micrometers wide, 5 micrometers long, and 2 micrometers thick, what is its surface area, volume, and surface area to volume ratio? (1 micrometer = 1/1,000,000 m) Show your work!

V = l x w x h = 5 µm x 3µm x 2µm= 30 µm3

3

52SAtot = SAT+B + SAR+L + SAF+B

= 2(3 µm x5 µm) + 2(5 µm x 2 µm) + 2(3 µm x2 µm) = 30 µm2

+ 20 µm2 + 12 µm2 = 62 µm2

SA:V = 62:30 = 62:30 = 2:1 30 30

2. If a plant cell is 7 micrometers wide, 7 micrometers long, and 7 micrometers thick, what is its surface area, volume, and surface area to volume ratio? (1 micrometer = 1/1,000,000 m) Show your work!

V = l x w x h = 7 µm x 7µm x 7µm= 343 µm3

7

77SAtot = (SA of 1 side) x no. of sides

= (7 µm x7 µm) x 6 = 294 µm2

SA:V = 294:343 = 0.9:1 = 1:1 343 343

Cells divide because as they get bigger, their volume increases faster than their surface area…..

3. Explain the roles of mitosis and interphase in the cell cycle.

• Mitosis = when body cells divide, making more body cells.

• Interphase = when cells grow, make copies of DNA, and get ready for mitosis.

4. What are chromosomes?

• Bundles of DNA in nucleus formed before mitosis..

5. Draw a simple diagram showing the four stages of mitosis. Label each stage and describe what happens to the chromosomes at each step.

Prophase: Chromosomes form

Metaphase: Chromosomes line up across middle.

Anaphase: Chromosomes pulled apart by spindles.

Telophase: Cell splitting into 2 cells, each with set of chromosomes.spindles

Interphase

How to memorize mitosis steps:

• Prophase-Metaphase-Anaphase-Telophase• Professionals Meet At Ten o’clock• Got a better one?

6. In mitosis, do daughter cells have the same number of chromosomes as the parent cell? Explain why or why not.

• Yes.• DNA is copied (replicated) before mitosis, so each daughter cell

gets complete set.

Parent cell

Daughter cells

Mitosis is how you make more body cells.

Parent cell

Daughter cells

Mitosis = “My toes-ees”. How you make more toe cells, body cells.

7. How are cancer cells different from normal cells?

Normal cells stop dividing when they come in contact with other cells. Cancer cells don’t.

8. What problems are likely to happen if cancer cells are left untreated?

• Tumors will keep growing, interfere with organ function.

• Cancer cells will get into blood and spread to other body parts.

9. What are the three most common treatments for cancer?

• Surgery• Chemotherapy• Radiation therapy

10. Give two reasons why cancer has been such a difficult disease to cure.

• Hard to kill cancer cells without killing normal, healthy cells.

• Really hard to get rid of it once it spreads.

• Many types of cancers with many different causes.

• Hard to cure genetic diseases.

• Constant exposure to chemicals that can cause cancer.

Questions?

HW: Study for test tomorrow!