Lymphocyte animations As seen in class

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Lymphocyte animationsAs seen in class!

• http//www.aimediaserver.com/studiodaily/harvard/h
  arvard.swf (music)
• http//multimedia.mcb.harvard.edu/anim_innerlife_h
  i.html (full length with narration)

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Membrane structure and functionChapter 7
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Figure 5.13 The structure of a phospholipid
AMPHIPATHIC molecule
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Butanol
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Figure 5.14 Two structures formed by
self-assembly of phospholipids in aqueous
environments   
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Permeability of membranes

• Can pass through the lipid bilayer-
• Small polar molecules (water)
• Non-polar molecules
• Small molecules and those less strongly
  associated with water will pass across membrane
• Cannot pass through the lipid bilayer-
• Large polar molecules
• Charged molecules

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The fluidity of membranes
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Figure 5.12 Examples of saturated and
unsaturated fats and fatty acids 
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Cis and trans fats
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• Margarine!

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Figure 5.14x Cholesterol    
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Effects of unsaturation of phospholipids

• Fluidity of membrane
• Important in cold blooded animals
• Saturated fats have higher melting point
• Conversion to cholesterol
• Harder to convert if more double bonds are
  present

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• Warm water fish
• More saturated fats
• Cold water fish
• More unsaturated fats

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The fluidity of membranes
Phospholipid translocators Flippases
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Figure 7.10 Sidedness of the plasma membrane

• Phospholipid translocators
• Flippase
• Scramblase

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Proteins in the membrane
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Figure 7.8 The structure of a transmembrane
protein
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Non-polar amino acids
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Porin
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Figure 7.6 Evidence for the drifting of membrane
proteins
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Figure 7.9 Some functions of membrane proteins
Cell Cell Adhesion
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Passive transport

• Diffusion
• Free-down concentration gradient
• Across membrane
• With or without channel proteins
• Facilitated diffusion

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Permeability of membranes

• Can pass through the lipid bilayer-
• Small polar molecules (water)
• Non-polar molecules
• Small molecules and those less strongly
  associated with water will pass across membrane
• Cannot pass through the lipid bilayer-
• Large polar molecules
• Charged molecules

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Figure 7.11 The diffusion of solutes across
membranes
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Figure 7.12 Osmosis
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Figure 7.13 The water balance of living cells
Figure 7.14 The contractile vacuole of
Paramecium an evolutionary adaptation for
osmoregulation
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Figure 7.15 Two models for facilitated diffusion
Diffusion down concentration gradient
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Active transport

• Pumps molecules or ions against a concentration
  gradient
• Requires the input of energy
• (e.g. ATP, light)

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Sodium (Na) Potassium (K) pump

• Cells maintain low intracellular Na
• 440mM outside, 50 mM inside
• Cells maintain high intracellular K
• 560mM inside, 90mM outside
• Ions cannot diffuse through lipid bilayer
• Sodium-Potassium dependent ATPase

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Figure 7.16 The sodium-potassium pump a
specific case of active transport
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Figure 7.18 An electrogenic pump
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Figure 7.19 Co-transport
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Figure 7.17 Review passive and active transport
compared
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Figure 7.20 The three types of endocytosis in
animal cells
Bulk transport into cells
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• Bulk transport into cells- solid materials such
  as cells

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Figure 6.14 The formation and functions of
lysosomes (Layer 3)
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• Bulk transport into cells- water and solutes

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• Bulk transport into cells-specific proteins

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Receptormediatedendocytosis
Nurse cell or oocyte cytoplasm
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Figure 8.3 Freeze-fracture and freeze-etch