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LIMITS TO SIZE

LIMITS TO SIZE. 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. © 2010 Paul Billiet ODWS. Surface area.

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LIMITS TO SIZE

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  1. LIMITS TO SIZE

  2. 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 © 2010 Paul Billiet ODWS

  3. 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 © 2010 Paul Billiet ODWS

  4. 1µm 2µm 3µm 4µm 5µm 6µm Growing cells © 2010 Paul Billiet ODWS

  5. Size / µm Surface area / µm2 Volume / µm3 SA/V How are surface area and volume affected by growth? 1 2 3 4 5 6 6 24 54 96 150 216 1 8 27 64 125 216 6 3 2 1.5 1.2 1 © 2010 Paul Billiet ODWS

  6. Comparing Surface Area and Volume changes © 2010 Paul Billiet ODWS

  7. Surface Area:Volume Ratio © 2010 Paul Billiet ODWS

  8. Solving the problem • Bigger cells have a greater metabolism than smaller cells • BUT bigger cells have a proportionallyless surface for exchange • How to increase surface area with increasing size? © 2010 Paul Billiet ODWS

  9. Throw out extensions Microvilli of small intestine epithelium Image Credit www.cytochemistry.net/

  10. Flatten into a thin film Image Credits http://anatomia.uw.hu/ Chick blastodisc

  11. Divide the cytoplasm into smaller volumes 8-cell Embryo Early human embryos Zygote Image Credit http://www.rmfcfertility.com/ Image Credit http://www.advancedfertility.com/

  12. Image Credit http://ecomerge.blogspot.com Multicellular organisms show the same adaptations • Flowering plants have an extensive, branched rooting system to absorb water and minerals

  13. Image Credit C. Candalh, INSERM Multicellular organisms show the same adaptations • Mammals have a long small intestine with internal folding to absorb digested food

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