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Biochemistry I > Chapter 11 Membranes > Flashcards

Chapter 11 Membranes Flashcards

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1
Q

What kind of structure is the biological membrane?

A

sheet like, few molecules thick, and self sealing

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2
Q

What does the biological membrane contain?

A

Contain amphipathic lipids, proteins and carbohydrates. Non-covalent Interactions (van deer walls which attract the nonpolar tails together)

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3
Q

_______ carry out most of the specific functions on the biological membrane.

A

Proteins

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4
Q

What are the membrane proteins functions contain?

A

receptors, enzymes, ion channels, calcium pumps

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5
Q

What are the carbohydrates on the membrane important for?

A

(attached to lipids = glycolipids, or to
proteins = glycoproteins) - important in communication/recognition
This is also the function of the post-translational modification (review assignment sheet)

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6
Q

What is the hydrophobic effect?

A

major driving force of the lipid bilayer

for example: mixing lipids and oils into water

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7
Q

______ and _______ form a lipid bilayer.

A

phospholipids and glycolipids

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8
Q

Membranes are _______ in that the outer surface is always different from the inner surface.

A

asymmetric (asymmetric arrangement)

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9
Q

Is the biological membrane polarized or unpolarized?

A

polarized: inside is negative (-60mV). Plays a role in transport, energy conversion and excitability.
- -Inside of axon is (-) and the ECF is (+)

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10
Q

What are the two types of diffusion in lipids?

A

Lateral and Transverse diffusion

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11
Q

Define lateral diffusion

A

rapid change of solid to liquid state

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12
Q

Define transverse (flip-flopping) diffusion

A

very slow (rare) change of solid to liquid state

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13
Q

How did they proof lateral diffusion existed?

A

They let bleach sit on a sample with lots of lipids and did a fluorescent recovery (FRAP) and found there was movement b/w lipids

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14
Q

What is the The Fluid Mosaic Model?

A

it describes the lipid bilayer of vesicles as a dynamic, liquid-like environment that allows the free motion of non-polar molecules throughout its structure.
(Proposed by Singer and Nicolson in 1972)

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15
Q

What are liposomes?

A

they are aqueous compartments enclosed by a lipid bilayer

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16
Q

What are the function of liposomes (lipid vesicles)?

A

they deliver chemicals/drugs/DNA to specific tissues

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17
Q

What is so special about liposomes?

A

They have an inner and outer aqueous compartment which helps in delivering chemicals to tissues. The aqueous compartments are enclosed by a lipid membrane

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18
Q

What is the function of the homing peptides on the outside of liposomes?

A

they help target what organ to go to

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19
Q

_____ have a harder time getting through the membrane when attached to H2O. They have to release the H2O as they go through the ______ to get through the membranes.

A 
Charged ions (Na, K, Cl) 
channels
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20
Q

H2O is special when going through membranes because it goes through by ________.

A

simple diffusion

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21
Q

When you have saturated fatty acids, more viscous (tightly packed), does the fluidity increase or decrease?

A

Decrease

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22
Q

When you have unsaturated (kinked) fatty acids, does the fluidity increase or decrease?

A

Increase

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23
Q

In saturated fatty acids (no double bonds), what does the melting temp and fluidity do? Increase or decrease?

A

Melting temp INC

Fluidity DEC

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24
Q

In unsaturated fatty acids (double bonds present), what does the melting temp and fluidity do? Increase or decrease?

A

Melting temp DEC

Fluidity INC

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25
Solid like means long chain fatty acids OR short chain fatty acids and saturated OR unsaturated fatty acids?
long chains of fatty acids | saturated (more compact)
26
Fluid like means long chain fatty acids OR short chain fatty acids and saturated OR unsaturated fatty acids?
short chains of fatty acids | unsaturated (less compact)
27
What are the 4 factors that determine solid like and fluid like?
Temperature, chain length, saturation vs. unsaturated, cholestrol
28
As the temperature increases, is that solid like or fluid like?
fluid like
29
As the temperature decreases, is that solid like or fluid like?
solid like
30
Longer chain of carbons, then its more compact, which means more ______ like.
solid
31
Unsaturated fatty acid means more kinks, which ______ fluidity
increase
32
__________ disrupts the tight packing of the fatty acid chains, therefore it is more ______ like.
Cholesterol, fluid
33
While membrane _______ establish a permeability barrier, membrane ______ allow transport of molecules and information across the membrane.
lipids | proteins
34
the more proteins, the MORE ______ are being transferred
molecules and ions
35
Integral Membrane Protein is embedded where?
in the membrane
36
Peripheral Membrane Protein is located where?
NOT embedded in the membrane, attached to extracellular surface
37
How are peripheral proteins attached to the surfaces of membranes (EC surfaces)?
Through being bound to head groups of lipids by electrostatic and hydrogen-bond, bound to integral membrane protein, or post-translationally modified to contain a fatty acid chain.
38
For one example of a peripheral membrane protein, the polimitate attaches to the ______ in the membrane.
cytseine
39
In an integral membrane protein, what would be the properties of the amino acids in the protein?
most of them are hydrophobic amino acids because they are embedded in the membranes away from the ECF
40
in porin, there is a barrel that allows the entry of charged ions and it has _______ amino acids on the inside
hydrophilic
41
Any protein that gets halfway or a quarter of the way through a membrane is classified as a _________
Intergral membrane protein
42
In the formation of prostaglandin H2 from arachidonate by prostaglandin H2 synthase, how many steps are needed for the final product?
2
43
____________ +___________ = | Prostaglandin H2 synthase
Cyclooxygenase + Peroxidase
44
What does the formation of prostaglandin H2 do?
Promotes inflammation & modulates gastric acid secretion. It produces fever.
45
How does ASA work?
-Aspirin inhibits cyclooxygenase activity by obstructing the channel which causes a conformational change with the protein and the arachidonic cant bind
46
What is the criteria for a molecule being able to pass through a membrane through simple diffusion?
1. The 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.
47
Polar molecules can diffuse across a membrane down their concentration gradient only with the assistance of a particular protein called a channel. Such movement is called ______ or _______.
facilitated diffusion or passive transport
48
Movement of molecules against a concentration gradient requires a source of energy and is called________.
Active tranport
49
What are the factors that determine simple diffusion across a membrane?
no assistance needed and molecules that dissolve in lipid. | Ex: Lipophilic molecule such as steroid
50
What are the factors that determine Passive Transport/Facilitated Diffusion across a membrane?
-Rate of diffusion enhanced by carrier or channel (integral membrane protein) and Rapid diffusion “down a concentration gradient -Energy comes from the molecule itself EX: sodium ions
51
What are the two types of active transport?
Primary and secondary
52
What is primary active transport?
transport of solute against its concentration gradient, where ATP required
53
What is secondary active transport?
ATP required; flow of one molecule promotes flow of another molecule (Antiporters vs symporters)
54
As the solute increases, the rate of transport ______
Increases
55
Functions of the Na+-K+ Pump (Na+-K+ ATPase)
- Controls cell volume - Promotes electrical excitability - Drives transport of sugars and Amino acids
56
What does Na+-K+ Pump pump? and where is the ATP located to drive the pump?
Pumps 3 Na+ out & 2 K+ into cell. ATP inside to drive the pump
57
Why are channels called P-type ATPases?
because the channel is phosphorylated and changes conformation
58
Examples of primary active transport
Na+-K+ ATPase Ca2+ ATPase H+-K+ pump
59
Examples of secondary active transport
Na+ -glucose symporter | Na+- Ca2+ Exchanger
60
In order for secondary active transport to work, it has to be what?
Coupled with a primary active transport
61
What is an antiporter secondary transport system?
the two substrates flow in opposite directions (ex: Na+ Ca+ channel)
62
What is a symporter secondary transport system?
the two substrates flow in the same direction (ex: Na+ glucose channel)
63
What are the 3 voltage gated cahnnels?
Na, K, and Ca
64
How does the selectivity filter work?
-Ion path begins (on inner surface) as wide, water-filled channel, so cations can enter with hydration sphere intact. Partway through membrane, channel narrows, so waters of hydration have to come off. -Carbonyl O atoms from protein backbone in selectivity filter region replace water molecules, binding to K+, with a series of perfect coordination shells through which K+ can move. -Na+ ions can't interact favorably with the filter (they're too small) and they don’t release the water as easily as K+.
65
What is Digitalis's function?
inhibits the Na+-K+ pump - increases Na+ inside of the heart and decreases K+ in the heart. - increase in intracellular Na+ slows down the expulsion of Ca2+. - increase in Ca2+ enhances contraction of the heart
66
Digitalis information
in heart disease the patients need the Ca+ in the cells so the digitalis is a drug that blocks the Na+ K+ pathway so more na+ is on the inside which then blocks the secondary AT and more Ca+ is stored on the inside ---The INC of Ca+ enhances the contraction of the heart
67
MultiDrug-Resistance (MDR) Proteins or | P-glycoprotein are over expressed in what?
tumors, drugs like chemo cant enter the cell because the cell uses the ATP to spit the drug out - This is because the tumors build a resistance to the drugs - 4 domains: 2 membrane spanning domain and 2 ATP-binding domain (ATP-binding cassettes-ABC). - ABC transporters
68
Where is the defect in this disease Harlequin Ichthyosis?
defect in ABC transporter for lipids in keratinocytes

Biochemistry I (7 decks)

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