1. Surface Area to Volume Ratio Concept
Glucose
Nutrients
Amino acids
Carbon dioxide
Metabolic waste
eg. urea
Volume determines the amount metabolism in the cytoplasm
Metabolism will require inputs that will need to enter the cell
Metabolism will result in production of
Waste products which will need to be removed from the cell and excreted.
Secretions that will need to be exported from the cell
Oxygen

2. Surface Area to Volume Ratio Concept
Metabolism occurs here
Uptake and removal occur via the membrane
Volume determines the amount metabolism in the cytoplasm
Metabolism will require inputs that will need to enter the cell
Metabolism will result in production of
Waste products which will need to be removed from the cell and excreted.
Secretions that will need to be exported from the cell

3. Surface area
Exchange of materials with the environment occurs across the cell surface
Surface area will effect the rate of the exchange
Bigger cells would generally have more metabolically active site
But they will would have a relatively small surface area across which to supply the metabolic needs
And the sites of metabolism in bigger cells will be further from the surface of the cell

4. Investigating effect of size on rate of diffusion into a cell
Let practise working this out
Investigating effect of size on rate of diffusion into a cell    
Let practise working this out
Size of cube
Side length (mm)
Surface Area
Volume
Surface area: volume
1mm
SA=lxlx6
  = 1X1x6
=6 mm2
V= l x l x l
=1x1x1
= 1mm3
SA:V
6: 1
Or 6 units of SA per unit of Volume
2mm
  SA=2x2x6
  =24 mm2
 V= 2x2x2
= 8mm3
 24: 8
Or 3 units of SA per unit of Volume
3 mm
  SA=3x3x6
  =54 mm2
 V= 3x3x3
= 27mm3
 54: 27
Or 2 units of SA per unit of Volume
Time taken to turn yellow

5. Comparing Surface Area and Volume changes
Side length of cubic cell(µm) 1 2 3 4 5 6
Surface Area (µm2) 24 54 96
150
216
Volume
(µm3) 8 27 64
125
SA:VOL
6:1
3:1
2:1
3:2
1.5:1
150:125
6:5
1.2:1
1:1

6. Comparing Surface Area and Volume changes
Length of cube side (um) Surface area( um2) Or Volume (um3)
© 2007 Paul Billiet ODWS

7. Surface Area:Volume Ratio
© 2007 Paul Billiet ODWS

8. Surface Area to Volume Ratio Concept
Why are cells so small?

9. Increasing surface area when a faster rate of uptake is needed

10. Throw out extensions Microvilli of small intestine epithelium
© copyright 2001 Gwen V. Childs, Ph.D., University of Arkansas for Medical Sciences
Microvilli of small intestine epithelium

11. Flatten into a thin film
© Developmental Biology Online
© Developmental Biology Online
Chick blastodisc

12. Divide the cytoplasm into smaller volumes
8-cell Embryo
Early human embryos
Zygote
© Reproductive Medicine and Fertility Center

13. Multicellular organisms show the same adaptations
Flowering plants have an extensive, branched rooting system to absorb water and minerals
© Illinois Enviromental Protection Agency
© Text 2007 Paul Billiet ODWS

14. Multicellular organisms show the same adaptations
Mammals have a long small intestine with internal folding to absorb digested food
lithograph plate 20th U.S. edition of Gray's Anatomy of the Human Body, originally published in This image is in the public domain because its copyright has expired
© Text 2007 Paul Billiet ODWS

15. Breaking up big things to speed rates of movement up