Plasma Membranes Flashcards

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1
Q

Functions of membranes? (5)

A
  • Keeps components inside
  • Selected molecules can move in and out
  • Isolating organelles
  • Site for reactions
  • Allows a change in cell shape
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2
Q

How does the phospholipid bilayer work? (2)

A
  • Hydrophilic heads make outer and inner lining to interact with aqueous surroundings
  • Double layer (bilayer)
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3
Q

What are intrinsic proteins? (4)

A
  • Embedded in the membrane
  • Amino acids with hydrophobic R-Groups
  • On external surfaces
  • Interacts to hydrophobic cores
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4
Q

What are channel proteins? (2)

A
  • Hydrophilic channel

- Passive movement of polar molecules

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5
Q

What are carrier proteins? (2)

A
  • Passive and active transport

- Involves the shape of the proteins changing

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6
Q

What are glycolipids? (2)

A
  • Lipids with attached carbohydrate

- Cell markers - recognised by immune system

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7
Q

What are extrinsic proteins? (3)

A
  • Hydrophilic R-Group
  • Interact with polar head of bilayer
  • Can be present in both layers and some can move between layers
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8
Q

What is cholesterol and its function? (5)

A
  • Lipid with a hydrophilic end and hydrophobic end
  • Positioned between phospholipids in bilayer
  • Hydrophobic reacts with tails and hydrophilic interacts with heads (pulls them together)
  • Provides stability without making it too rigid
  • Prevents membrane from becoming too solid- stopping the phospholipid molecules from grouping too closely and crystallising
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9
Q

How does temperature affect membrane structure? (3)

A
  • Phospholipids are always moving
  • Higher temp. means more kinetic energy so more movement
  • Begins to lose its structure and will eventually break down completely if temperature continues to rise
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10
Q

How do solvents affect membrane structure? (4)

A
  • Water (polar solvent) helps keep the bilayer together
  • Alcohols dissolve membrane in bacteria
  • As alcohol is nonpolar, it can pass through membrane - causes damage and disruption in the membrane
  • Affects neurons in brain when people are intoxicated
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