limits to size © 2007 paul billiet odwsodws. volume volume determines the amount metabolism in the...
DESCRIPTION
Surface area Surface area will determine the exchange of materials between the cell and its environment Bigger cells will metabolise more But they will need more surface to support that metabolism And the sites of metabolism in bigger cells will be further from the surface of the cell © 2007 Paul Billiet ODWSODWSTRANSCRIPT
Volume
Volume determines the amount metabolism in the cytoplasm
Metabolism will require import of precursors
Metabolism will result in the export of secretions
And the export of excretory products© 2007 Paul Billiet ODWS
Surface area Surface area will determine the exchange of
materials between the cell and its environment
Bigger cells will metabolise more But they will need more surface to support that
metabolism And the sites of metabolism in bigger cells will
be further from the surface of the cell
© 2007 Paul Billiet ODWS
Growing cells
1µm
2µm
3µm
4µm
5µm
6µm© 2007 Paul Billiet ODWS
How are surface area and volume affected by growth?
11.21.5236
216125642781
2161509654246
654321
SA/V
Volume / µm3
Surface area / µm2
Size / µm
© 2007 Paul Billiet ODWS
Comparing Surface Area and Volume changes
0100200300400500600700800900
1000
0 1 2 3 4 5 6 7 8 9 10Size / µm
Surface areaVolume
© 2007 Paul Billiet ODWS
Surface Area:Volume Ratio
0
1
2
3
4
5
6
0 1 2 3 4 5 6 7 8 9 10Size / µm
SA/V
© 2007 Paul Billiet ODWS
Solving the problem Bigger cells have a greater metabolism
than smaller cells BUT bigger cells have a proportionally
less surface for exchange How to increase surface area with
increasing size?
© 2007 Paul Billiet ODWS
Throw out extensions
Microvilli of small intestine epithelium
© copyright 2001 Gwen V. Childs, Ph.D., University of Arkansas for Medical Sciences
Flatten into a thin film
Chick blastodisc© Developmental Biology Online © Developmental Biology Online
Divide the cytoplasm into smaller volumes
Early human embryos
Zygote
8-cell Embryo
© Reproductive Medicine and Fertility Center
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
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 1918. This image is in the public domain because its copyright has expired
© Text 2007 Paul Billiet ODWS