Cell Membranes And Transport (chapter 4) Flashcards

1
Q

Phospholipid

A

Hydrophilic head
Hydrophobic tail

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2
Q

Hydrophobic

A

Water hating - fat loving

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3
Q

Hydrophilic

A

Water loving - fat hating

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4
Q

Bilayer

A

Phospholipid bilayer

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5
Q

Amphipathic

A

One end hydrophilic, other end hydrophobic

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6
Q

Unsaturated hydrocarbon

A

Degree of Unsaturation (double bonds) in tail (more = more fluid)

Unsaturated hydrocarbons - tails with kinks

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7
Q

Saturated hydrocarbon

A

Length of fatty acid tail (longer = more viscous)
Saturated hydrocarbon tails = no kinks, straight

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8
Q

Desaturase

A

Desaturase enzyme makes double bonds (kink)

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9
Q

Cholesterol

A
  • Cholesterol is in the membrane of animal cells
  • Cholesterol counters the effects of temperature extremes:
    • high temps, reduces membrane fluidity by restraining movement of lipids
    • low temps, increases membrane fluidity by preventing lipids from ordering
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10
Q

Integral membrane (transmembrane) proteins

A

Contains hydrophobic domains that cross the bilayer

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11
Q

Peripheral proteins

A

Sit on the surface and form non-covalent bonds with lipids and membrane proteins

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12
Q

Passive transport

A

Transport from high to low concentration is driven by increase in entropy
1. Diffusion
2. Facilitated diffusion

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13
Q

Active transport

A

Transport against the concentration gradient (from low to high concentration) requires energy
1. Primary - uses ATP
2. Secondary - uses electrochemical gradients

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14
Q

Diffusion

A

Things move from high to low concentration “down their concentration gradient”
(Non-polar molecules) (small uncharged polar molecules)

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15
Q

Osmosis

A

Movement of a solvent from high to low concentrations

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16
Q

Hypotonic solution

A

Solution concentration < cell concentration
Volume increases (water moves into the cell)

17
Q

Hypertonic solution

A

Solution concentration > cell concentration
Volume decreases (water moves out of the cell)

18
Q

Isotonic solution

A

Solution concentration = cell concentration
Volume stays the same (stays the same)

19
Q

Simple diffusion

A

Small and uncharged molecules diffuse rapidly

20
Q

Facilitated diffusion - channel proteins

A

A. Channel protein
B. Gated channel protein
C. Carrier proteins

21
Q

Channel protein

A

From hydrophilic channels in the membrane through which water and ions can move

22
Q

Channel protein: Aquaporin

A

An aquaporin is a water channel. Water molecules move through channel by being handed off to a succession of hydrogen-bonding sites in the channel

23
Q

Gated channel proteins: K+ voltage-gated channel

A

Normal voltage across membrane, activation gate of K+ closed (no movement)

Response to voltage change across membrane, activation gate of K+ opens up for movement

24
Q

Carrier protein

A
  1. In conformation so that binding site is exposed toward region of higher concentration
  2. Solute molecule binds to carrier protein
25
Primary active transport (example: sodium-potassium pump)
- moves sodium ions (NA+) out of cell - moves potassium ions (K+) into cell - the transporter uses ATP to do this Both ions are moved against their concentration gradient so energy is needed
26
Secondary active transport
- does not use ATP - uses ion gradients (electrochemical) for energy - energy is released as an ion moves **with** its concentration gradient is used to drive movement of a solute **against** its concentration gradient
27
Symport
The transported solute moves in the same direction as the gradient of the driving ion
28
Antiport
The transported solute moves in the direction opposite from the gradient of the driving ion
29
Micelle
Micelle is water forms an aggregate with the hydrophilic “head” regions in contact with surrounding solvent. Hydrophobic single-tail regions in the centre on the micelle
30
Selective permeability
Polymeric membrane that will allow certain molecules or ions to pass through by osmosis
31
Uniport
Membrane transport protein that transports a single substrate across a cell membrane
32
Electrochemical gradient
Gradient of electrochemical potential