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Biochemistry > Unit 3: Chapter 12 > Flashcards

Unit 3: Chapter 12 Flashcards

1
Q

Characteristics of Membrane

A
  1. sheetlike structures
  2. composed of lipids and proteins which can be decorated with carbohydrates
  3. membrane lipids are small amiphipathic molecules which prevent movement of polar or charged molecules
  4. proteins serve to mitigate impermeability of membranes
  5. noncovalent assemblies
  6. asymetric
  7. fluid structures
  8. electrically polarized
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2
Q

What form lipid bilayers in aqueous solutions?

A

phospholipids and glycolipids

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3
Q

Formation of membranes is powered by

A

Hydrophobic effect

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3
Q

Liposome/ Lipid Vesicles

A

Double layered formed by phospholipids
Amphipathic
Very small aqueous compartment enclosed by a lipid membrnae
Used as drug delivery systems

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4
Q

The phospholipid bilyaer membrane is stabilized by

A

energy gained from hydrophobic groups burying hydrophobic groups out of contact with water
1. hydrophobic chain in water forces the formation of a cage of water around it
2. several hydrophobic regions cluster in bilayer, surface area exposed to water decreases and water molecules in cage are released (increase in entropy to drive formation of water)

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5
Q

Micell

A

Single hydrophobic tail instead of double
Inside is more hydrophobic

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6
Q

Lipid bilayerd are highly imermeable to ions and most polar molecules due to

A

Hydrophobic tail is picky

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7
Q

Larger permeability coefficient represents

A

increasing permeability
(easy to cross membrane)

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8
Q

What are the best molecules to cross membrane?

A

Small, uncharged, nonpolar
Ex. H20, indole, uren, glycerol

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9
Q

What is membrane fluidity controled by?

A

Fatty acid composiiton and cholsterol content

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10
Q

Membrane temperature is dependent on

A

Length of fatty acids and degree of cis saturation

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11
Q

Increasing temperature causes what to membrane

A

Increases fluidity of membrane to make more fluid like

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12
Q

Decreasing temperature causes what to membrane

A

Decreases fluidity of membrane to make more solid like

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13
Q

Abrupt transition between fluid like and solid like of membrane depends on

A

length of fatty acid chains and degree of unsaturation

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14
Q

How does cholesterol determine membrane fludiity in animals?

A

Makes membrane from becoming too rigid and too fluid
helps resist change and acts like buffer
1. prevent solidying at temp below Tm (too rigid)
2. sterically blocks large amount of fatty acids at temperature above Tm (too fluid)

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15
Q

What decreases fluidity of membrane?

A

Increase fatty acid tail
More closely packed
Less double bonds (saturated)

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16
Q

Why are proteins second most common componet of membrane?

A

Proteins allow transport proteins of molecules and information across the membrane

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17
Q

Integral membrane proteins

A

Embedded across entire membrane

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18
Q

Peripheral membrane proteins

A

Bound to polar head groups of membrane lipids or exposed surfaces of integral membrane proteins

19
Q

Common structure of integral proteins

A

membrnae spanning alpha helices and beta strands

20
Q

Bacteriorhodopism

A

Integral protein
Made of 7 alpha helices

21
Q

Bacterical porin

A

Found in mitochondria, chloroplast, and bacteria
Forms pore or channel to help ions pass

22
Q

How do lipids and membrane proteins diffuse

A

Laterally (side to side) in same layer
Rapid
- But can also use transverse diffusion

23
Q

Fluorescence recovery after photobleaching (FRAP)

A

Technique that allows measurement of lateral mobility of membrane componets

24
Q

Transverse diffusion

A

AKA flip flop
Very slow
Lipids and membrane proteins move to one layer to the other
Requires protein and enzyme for help
Reason why membrnae composiiton is asymmetric

25
Q

Flippase

A

Moves membrane lipids from outer leaflet to the inner leaflet during transverse diffusion

26
Q

Major function of membrane proteins is to function as

A

Transporters
(Simple transport and active transport)

27
Q

Small molecules will spontaneously occur if:
(simple diffusion)

A
  1. concentration of the molecule is higher on one side of the membrane than the other
  2. the molecule is lipophilic or soluble in nonpolar solutions
28
Q

Simple diffusion

A

Passive transport
No proteins used to assist

29
Q

Facilitated diffusion

A

Passive transport
Polar molecules diffuse across membrane down their concentration with assistance of channel proteins

30
Q

Active transport

A

Movements of molecules against concentration from low to high that requires source of energy and proteins

31
Q

2 classes of membrane transport:

A

Channels and Transporters

32
Q

Channels

A

Used in passive transport
Selective
No conformation change

33
Q

Transporters

A

Used in passive and active transport
Specifity
Conformational change with gates
Function as pumps and channels

34
Q

Passive transport

A

Molecules move with concentration gradient from high to low concentration
No energy required

35
Q

Na+ - K+ pump

A

Active transport using ATP hydrolysis
Simutaneously pump 3 Na+ ions out and 2 K+ ions in against concentration gradient
Both against electrochemical agents
Keep concentration gradient of Na+ outside
Na+ concentration gradient is energy source

36
Q

Most animal cells contain concentrations of

A

High concentration of K+ and low concentration of Na+

37
Q

What concentration is more outside cell?

A

Na+ concentration

38
Q

What concentration is more inside cell?

A

K+ concentration

39
Q

Secondary Transporters

A

( 2 things moving)
Use one concentration gradient to power formation of another

40
Q

Symporters

A

Secondary transporters
Molecules move in same direction

41
Q

Antiporters

A

Secondary transporters
Molecules move in opposite directions

42
Q

How is gluocse moved into animal cells

A

Active transport against concentration gradient
Symporter powered by Na+ concentration as energy source and moves down concentration gradient

43
Q

Ion channels

A

Passive transport systems
Activated by changes in voltage or by binding of specific molecules to the channels

44
Q

Electrochemical gradient forces

A
  1. chemical gradient: concentration gradient
  2. electrical gradient: membrnae potential (voltage gradient)

Biochemistry (17 decks)

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