Presentation is loading. Please wait.

Presentation is loading. Please wait.

WHY DO CELLS DIVIDE? 10-1. ITS ALL ABOUT SIZE WHY DO CELLS DIVIDE? (instead of just getting bigger) 1.Diffusion 2.DNA 3.Surface area-to-volume ratio.

Similar presentations


Presentation on theme: "WHY DO CELLS DIVIDE? 10-1. ITS ALL ABOUT SIZE WHY DO CELLS DIVIDE? (instead of just getting bigger) 1.Diffusion 2.DNA 3.Surface area-to-volume ratio."— Presentation transcript:

1 WHY DO CELLS DIVIDE? 10-1

2 ITS ALL ABOUT SIZE

3 WHY DO CELLS DIVIDE? (instead of just getting bigger) 1.Diffusion 2.DNA 3.Surface area-to-volume ratio

4 Diffusion Cells need: –food and oxygen –to eliminate wastes –to move all materials through cytoplasm

5 Diffusion Typical cell has a diameter of 20 µm –takes a fraction of a second for materials to move from cell membrane to the center of the cell If it had 20 cm diameter –would take months to move materials same distance The cell would die from starvation or poisoning from wastes before it got that big

6 DNA Cell needs: –to respond to changing conditions rapidly –to produce large amounts of proteins and enzymes

7 DNA DNA directs the production of proteins and enzymes –DNA makes an RNA copy –RNA leaves the nucleus and travels to a ribosome –RNA directs protein production at the ribosome

8 DNA If there is not enough DNA to control the cell the metabolism will slow and the cell will die

9 WHY DO CELLS DIVIDE? (instead of just getting bigger) 2. DNA Larger cell = Greater metabolism

10 DNA Greater metabolism = More DNA needed to direct metabolism

11 Surface area-to-volume ratio As size of a cell increases, volume increases at a much greater rate than does surface area

12 Surface area-to-volume ratio Cell needs: –materials for processes obtains materials through its cell membrane –larger organisms (or cells) need more stuff more and more materials as its volume increases –surface area for absorbing required materials (not enough surface area to supply the needs for larger cells)

13 Surface area-to-volume ratio Example: Surface area of a cube = area of 1 side x 6 1 inch Area of 1 side = length x width = 1 in x 1 in Surface area = 1 in 2 x 6 = 6 in 2 = 1 in 2

14 Surface area-to-volume ratio Example: Volume of a cube = length x width x height 1 inch = 1 in x 1 in x 1 in = 1 in 3

15 Surface area-to-volume ratio Example: Surface area : Volume ratio = 6 : 1 1 inch Surface area = 6 in 2 Volume = 1 in 3

16 Surface area-to-volume ratio Example: Surface area of a cube = area of 1 side x 6 4 inches Area of 1 side = length x width = 4 in x 4 in Surface area = 16 in 2 x 6 = 96 in 2 = 16 in 2

17 Surface area-to-volume ratio Example: Volume of a cube = length x width x height = 4 in x 4 in x 4 in = 64 in 3 4 inches

18 Surface area-to-volume ratio Example: Surface area : Volume ratio = 96 : 64 Surface area = 96 in 2 Volume = 64 in 3 = 3 : 2 4 inches

19 Surface area-to-volume ratio Example: Surface area : Volume ratio = 3 : 2 4 inches Surface area : Volume ratio = 6 : 1 1 inch


Download ppt "WHY DO CELLS DIVIDE? 10-1. ITS ALL ABOUT SIZE WHY DO CELLS DIVIDE? (instead of just getting bigger) 1.Diffusion 2.DNA 3.Surface area-to-volume ratio."

Similar presentations


Ads by Google