Biological Membranes Flashcards

0
Q

Membrane composition

A

Asymmetric, heterogenous (protein and lipid)

Lipid clusters and lipid-protein aggregates

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1
Q

Functions of membranes

A
Barrier to toxins 
Transport and accumulation of nutrients
Energy transduction
Facilitation of cell motion
Reproduction
Signal transduction
Cell cell interactions
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2
Q

Integral membrane proteins

A

Attached or anchored to the membrane

Globular proteins totally in the membrane

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3
Q

Peripheral membrane proteins

A

Generally globular, interact electrostatically/hydrogen bond with integral membrane proteins

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4
Q

Lipid anchor proteins

A

Proteins attached to membranes through lipid tails

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5
Q

Types of lipid anchored proteins

A

Amide linked myristoyl anchor
Thioester linked fatty acyl anchor
Thioester linked prenyl anchor
Glycosyl phosphatidylinositol anchor

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6
Q

Lipid anchor composition

A

Always myristic acid and N-terminal Gly residue

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7
Q

Prenyl

A

Long chain polyisoprene units

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8
Q

Target of isoprene units

A

C-terminal CAAX motif

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9
Q

Farnesyl

A

3 isoprene units

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10
Q

Geranylgeranyl

A

4 isoprene units

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11
Q

Types of lipid movements in membranes

A

Rotational diffusion, protrusion, flip-flop, lateral diffusion, bond vibrations, Gauche-trans isomerization

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12
Q

Membranes at low temperatures

A

Highly ordered, called solid ordered state, little motion, chains are fully extended, thickness is maximal

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13
Q

Membranes at high temperatures

A

Lots of motion, liquid crystalline phase or liquid disordered state, chains likely to be bent, gets thinner

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14
Q

Types of transporters

A

Passive diffusion, facilitated diffusion, active transport

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15
Q

Passive diffusion

A

Purely entropic, moves down a concentration gradient

16
Q

Facilitated diffusion

A

Used for charged solutes

17
Q

Active transport

A

Uses a positive concentration gradient, thermodynamically unfavorable, uses ATP, possible to couple a favorable and unfavorable process