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Size Matters!

Size Matters!. Size Matters!. Size Matters!. Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit. A molecule. 1nm. http://mendosa.com/glucose_molecule.jpg. Glucose (1nm). A molecule. 10nm.

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Size Matters!

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  1. Size Matters! Size Matters! Size Matters!

  2. Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit. A molecule 1nm http://mendosa.com/glucose_molecule.jpg

  3. Glucose (1nm) A molecule 10nm http://www.biolibogy.com/images/structure_of_plasma_membrane.JPG

  4. A virus – the T bacteriophage 100nm 10nm http://oceanworld.tamu.edu/resources/oceanography-book/Images/BacteriophageCartoon.jpg

  5. Bacteriophage (virus) E.coli (bacteria cell) 100nm 0.1µm 1000nm1µm http://bio1903.nicerweb.com/doc/class/bio1903/Locked/media/ch18/18_01T4PhageEColi_LP.jpg

  6. Bacteria (1µm) Organelle (10µm) Eukaryote Cell (100µm) http://www.cic-caracas.org/departments/science/images/08eukaryote.jpg

  7. In the last sequence of slides every thing increased by a magnitude of 10x each time. The IB requires you to remember the sizes. • Make up a mnemonic to help you to remember the order! • My Crazy Mum Visits BieberOutside Concerts. • My Money Vanishes Beautifully On Cars. • My Most Valued subject is BiO ! Cool!

  8. Lets look at Surface areas and volumes……… • Fill in the table below: a a a

  9. What trend did you notice? • What happened to the area as side size increased? The area increased much faster than the side size. • What happened to the volume? The volume increased much faster than the side size • Which one (area or volume) increased the fastest?

  10. Why is this important? • The surface area relates to how much material can enter a cell at a time. The bigger the area is the more material can enter in an amount of time

  11. The volume relates to how much material is needed at a time. The bigger the volume is the more material is needed to maintain it for an amount of time.

  12. Assume that a volume of 1 needs 1 lot of material to sustain it….And an area of 1 can provide 1 lot of material: a a • Look at cell size where a=1. Is it able to supply its needs? • Look at cell size where a=6. Is it able to supply its needs? • What about a=7? a Area = 6 Volume =1 ….It can provide 6x as much material than it needs Area = 216 Volume =216 ….It can just provide as much material than it needs

  13. The same idea is relevant for heat and waste needing to be given out by an organism.

  14. Can you think of some organisms that have to deal with this problem? • Elephant – a very big organism produces lots of heat. How does it get rid of all the heat with a relatively low SA : Vol ratio? • Find out about elephant ears. • The Shrew – A very small organism with a relatively large SA : Vol ratio. How does it manage to stay warm in winter? • Find out about changes in metabolism.

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