Membranes, Osmosis and Diffusion

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Membranes, Osmosis and Diffusion

• All for homeostasis

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Solution Review

• Isotonic --
• Hypotonic --
• Hypertonic --

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Draw each solution in a diagram and show whats
happening
water
Egg
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How does the water move in this lab?

• OSMOSIS
• THE MOVEMENT OF WATER

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ONION CELL LAB CONCLUSION

• Cells shrunk in the salty water
• They lost mass (water)
• Water in the onion moved outside the cell

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Why are fluids entering/leaving cells?

• Cell membrane has holes
• Membrane is semi-permeable
• It is selective about what goes in or out

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What gets in or out?

• Water
• Oxygen
• Nutrients
• Carbon dioxide
• Wastes
• Nitrogenous wastes

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What systems of the body work with the cell
membranes to deliver and take away these
substances?
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Cell Membranes

• Semi-permeable ability to regulate what gets in
  and out
• Boundary between the inside and outside
  environment

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Structure

• Made of two layers of fat (lipids)
• Called ? lipid bi-layer
• Ends that dont like water point inward
  (hydrophobic)
• Helps keep the membrane together

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Proteins embedded in the lipids

• Proteins are chains of amino acids
• Aid in communication from the inside outside of
  the cell
• Act as carriers, transporting certain molecules
  across the membrane
• Some act like channels, letting water soluble
  ions pass in and out

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Proteins are the brain of the membrane.

• Ion charged atoms that get thru
• Sodium and Potassium common ions

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Cell Membrane
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Movement of Molecules

• How are these substances moving thru the
  membranes?

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1. Diffusion

• Molecules spread out in random directions
• from an area where they are more concentrated to
  where they are less concentrated

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Go with the flow downstream --no extra energy
needed to diffuse outward.
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Concentration Gradient

• The area of separation between two different
  concentrations

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Water movement

• Water moves from an area of greater water
  concentration to an area of less water
  concentration
• OSMOSIS

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Passive transport

• Diffusion and Osmosis are examples
• No extra energy required
• go with the flow

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Active Transport

• When a molecule is moved into a cell using energy
• going upstream

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Advantage of membrane- enclosed compartments.

• Protection
• Control level of oxygen, pH, temp., nutrients,
  minerals, amount of water, etc..

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Cell Compartments to know..

• Nucleus Vacuoles
• Mitochondria Cytoplasm
• Ribosomes Chloroplasts
• ER- Endoplasmic Reticulum
• Lysosomes
• Golgi Bodies
• Microtubules