Cells

50 TRILLION!!! (50,000,000,000,000) cells in the human body

• http://www.cellsalive.com/howbig.htm

• You shed millions of skin cells per hour

• By one month you have completely replace the outer layer of your skin

• The dust that settles on your furniture is a grey color, 70% is tiny flakes of mostly human skin.

Every minute the body produces ~300 million new cells

• Predict which cells in our body reproduce more frequently & which is less?

Red blood cells Stomach Lining cells

Liver cells Intestinal Lining cells

Brain cells Skin cells

20 days

200 days

120 days 2 days

3 days

30- 50 years

20-30 trillion RBC in the body

Cells divide and make more cells to help us grow and repair in a process called mitosis.Calculate how many skins cells will result from just 1 cell that continually divides during a period of 30 days

Day Number of Cells Day Number of Cells Day Number of Cells

1 2 11 2,048 21 2,097,152

2 4 12 4,096 22 4,194,304

3 8 13 8,192 23 8,388,608

4 16 14 16,384 24 16,777,216

5 32 15 32,768 25 33,554,432

6 64 16 65,536 26 67,108,864

7 128 17 131,072 27 134,217,728

8 256 18 262,144 28 268,435,456

9 512 19 524,288 29 536,870,912

10 1,024 20 1,048,576 30 1,073,741,824

1. A mass of cells would become just visible to the eye at about 1 mm in width, which is 250, 000 cells. On which day would the cell mass be visible? Explain.

The mass would be visible on day 19 (between 18 and 19 would be 250,000)

2. If a tumor was detected when it was about 1 cm in width, how many days would the cells have to divide for the tumor to reach this size?

1 cm = 10 mm; therefore, 10 times 250,000 cells = 2, 500, 000, which would be day 22.

3. What do you think would happen if certain cells in the human body continually divided without stopping? These cells would form a tumor.

4. Look at the pattern in the numbers you entered in the chart. How could you quickly calculate the number of cells that would be present after a particular number of days had passed, for example, 50 days?

2 to the power of the number of days = 2n. 250 = 1.12589991 x 1015.

Day Number of Cells Day Number of

Cells Day Number of Cells1 2 11 2,048 21 2,097,1522 4 12 4,096 22 4,194,3043 8 13 8,192 23 8,388,6084 16 14 16,384 24 16,777,2165 32 15 32,768 25 33,554,4326 64 16 65,536 26 67,108,8647 128 17 131,072 27 134,217,728

8 256 18 262,144 28 268,435,456

9 512 19 524,288 29 536,870,912

10 1,024 20 1,048,576 30 1,073,741,824

Debate

• Read the statement on the screen. Think for a few moments about whether you Strongly Disagree, Disagree, Agree, Strongly Agree.

• Once Mr. Cadman tells you to, get up and go to a section. • Pair up and discuss with a partner what your reason is. • Volunteers to state their reasoning.• If you hear something that changes your mind, you can switch

corners once they finish speaking.

Debate Questions

1. We should clone extinct species. (e.g. dinosaurs)

2. We should clone humans and/or organs.3. We should be able to select what traits

our children will have.4. Researchers should be allowed to

combine the genomes of two different speices. (e.g. mate giraffe and hippo, aka “giro”)