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Biochemistry > Biochem Exam 2: Membranes & Membrane Transport > Flashcards

Biochem Exam 2: Membranes & Membrane Transport Flashcards

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1
Q

Biological membranes consist of these three things

A

Lipids, proteins, and carbohydrates

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2
Q

A common feature of biological membranes is that it __________________ organelles

A

Comparmentalizes

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3
Q

What type of bonding do lipids have?

A

Hydrophobic, electrostatic, & vander waals forces

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4
Q

Membranes are symmetrical, true or false

A

False; membranes are asymmetric

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5
Q

What are the primary components of the biological membrane?

A

Phospholipids

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6
Q

Carbohydrate molecules are ____________ attached to some membrane lipids or proteins

A

Covalently

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7
Q

Location of membrane lipid: sphingomyelin

A

Outer sheet

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8
Q

Location of membrane lipid: phosphatidylserine

A

Inner sheet

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9
Q

Location of membrane lipid: phosphatidylcholine

A

Outer

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10
Q

Location of membrane lipid: phosphatidylinositol

A

Inner

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11
Q

Location of membrane lipid: glycolipids

A

Outer

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12
Q

Location of membrane lipid: phosphatidylethanolamine

A

Inner

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13
Q

Why is the lipid bilayer favored over Micelle?

A

Micelle can only fit one fatty acid tail, and proteins wont fit into its structure

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14
Q

Formation of lipid bilayer is and why:
A. Spontaneous
B. Nonspontaneous

A

Spontaneous (self assembly)

Majoritively due to hydrophobic interactions

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15
Q

Lipid bilayers have very low permeability for ions and most polar molecules; true or false

A

True

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16
Q

How is a liposome created?

A

By suspending a phosphatidylcholine and sonicating to give a dispersion of closed uniformly sized vesicles

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17
Q

What are some therapeutic applications of liposomes?

A

Can contain DNA,RNA,peptides,& antibodies
Reduces toxicity
Very targeted

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18
Q

What does sodium dodecylsulfate polyacrylamide gel electrophoresis show? (SDS/PAGE)

A

Proteins via their weight
Heavier proteins migrate slower
Lighter proteins migrate quicker

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19
Q 
This protein type:
Spans the lipid bilayer
Interacts extensively with hydrocarbons
And is released via detergents
What classification of membrane proteins is this?
A

Integral

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20
Q

This membrane protein classification requires we completely break the membrane to get the protein out; we have to use detergents. What membrane protein classification is it?

A

Integral

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21
Q

This classification of membrane protein:

  • Is bound to he membranes primarily by electrostatic and hydrogen bond interactions
  • is released from the membrane by adding salt or changing pH
A

Peripheral membrane proteins

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22
Q

Which classification of membrane proteins dissociate from membrane by salt or changing pH

A

Peripheral proteins

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23
Q

Bacteriorhodopsin has what type of helix and what is it know for?

A

Alpha helices, membrane spanning alpha helices with most of being formed by nonpolar amino acids

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24
Q

A protein made mostly of nonpolar amino acids would be found where in the membrane?

A

In the hydrophobic area of the membrane

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25
Porin is made mostly of what type of strand?
Beta Each beta strand hydrogen bonds to the next in an antiparellel forming a single sheet that curls to form a cylinder/ pore or channel
26
Equal mixing of hydrophobic and hydrophilic amino acids can indicate ____________
Beta sheet formation
27
Cyclooxygenase (COX1); what does it do and what type of protein is it?
Covert sarachidonic acid to prostaglandin H2 Integral protein that bind to luminal leaflet of ER Made primarily of alpha helices NOT a membrane spanning protein Can be removed using salt or ph change Works to create inflammation
28
How does COX1 channel work to block pain?
Aspirin acetylates the serine, blocking the channel, changing to prostaglandin which blocks pain
29
Lipid-linked protein Palmitoylation
Palmitate acid is attached to cysteine by alpha thioester bond
30
Lipid linked protein: Farnesylaaiton
Farnesylatic acid is attached to a cysteine at the C-terminus
31
Lipid-linked protein: Glycosylphosphatidylinositol (GPI)
GPI linked to carboxyl not cysteine in membrane
32
What was FRAP (fluorescence recovery After Photo-bleaching) used for?
To study lateral diffusion
33
What are the three factors that influence membrane fluidity?
Temperature Lipid composition Cholesterol
34
How does cholesterol affect membrane fluidity?
It can either increase or decrease membrane fluidity
35
What are transport proteins referred to as?
Polytopic transmembrane integral membrane proteins
36
Na is higher inside or outside the cell?
Outside
37
Potassium is higher inside or outside the cell?
Inside
38
Calcium is higher inside or outside the cell?
Outside (1 to 0.0001)
39
Chloride is higher inside or outside the cell?
Outside
40
What type of molecules use Simple diffusion
Small, non-polar, uncharged diffuse freely
41
What type of molecules use facilitated diffusion?
Large and charged
42
``` If there is positive free energy then what process is being used? Passive transport Facilitated diffusion Diffusion Active transport ```
Active transport
43
How is active transport mediated?
Integral membrane proteins
44
How does primary active transport differ from secondary active transport?
Primary used ATP directly
45
How does secondary activity transport differ from primary active transport?
Secondary used energy stored in a concentration gradient coupled to primary transport system
46
What are P-type ATPases?
ATP hydrolyzed, protein gets phosphorylated
47
List the different types of P type ATPases
Na K ATPase Plasma Membrane Ca-ATPase (PMCA) Sarcoplasmic reticulum CA-ATPase (SERCA) H K ATPase
48
What do ATP binding Cassette transporter do?
ATP hydrolyzed, but ported does not get phosphorylation
49
List types of ATP binding Cassette Transporters
MDR, P-glycoproteins
50
During p-ATPase the transporter forms a covalent bond with the phosphate to form an enzyme-phosphate intermediate; true or false?
TRUE
51
How many molecules of Na per K are pumped?
3 Na/ 2 K
52
What does the Na/K pump drive?
Active transport of sugars and amino acids
53
________% of brain ATP used by the NA pump
25-40%
54
Digitoxigenin and ouabain is used to do what concerning active transport?
Inhibit na pumps Cardio tonic steroid Used to treat congestive heart failure
55
Digoxin and ouabain act as cardio tonic which means
They are Contraction inducing
56
Digoxin inhibits what pump, which leads to what?
Na/ K ATPase | Lead to increase in intracellular sodium, secondary leads to increase in Ca due to slowing of the NCX
57
What transport am I describing? Transports calicium from cytosol to extracellular side Maintains 10,000 fold gradient across its membrane Protein with 10 transmembrane domains Uses ATP to pump calcium against its gradient Stimulated by calcium binding protein calmodulin (CaM)
PMCA
58
``` What transport pump am I describing? 10 transmembrane domains Lacks the c terminal CaM binding domain Transports calcium from cytosol to ER Uses ATP Plays role in relaxation of contracted muscle ```
SERCA
59
ABC transporters, what are they?
Active transports that use ATP but do not phosphorylate | Human genome has 150
60
Example of symporter?
Lactose permeate
61
Example of uniporter?
Mitochondrial calcium transporter
62
Na Ca pump is known as what type of pump and functions to maintain what concentrations?
Secondary active pump Calcium low intracellular Imports 3 NA into cell & exports 1 Ca against gradient
63
What type of membrane transport am I describing? Integral,polytopic membran protein Over 400 genes code for it Facilitated passive transport 1000x faster than pump Highly selective and specific Responds to physical and chemical changes Opening and closing Shapes the membrane potential
Ion channel
64
3 types of ion channels?
Voltage-gate Chemically gate Mechanically gated
65
Responds to ligands such as neurotransmitters
Chemically gated
66
Responds to change in membrane potential
Voltage gated
67
Responds to mechanical stimuli, detects vibration, pressure, stretch, tough, sounds, tastes, smell, heat, volume, and vision
Mechanically gated
68
S1-S4 in a potassium channel function as?
Voltage sensors
69
S5-S6 in potassium channels function as?
Pore
70
How does the ion channel regulate its molecule it moves?
Selectivity filter | Carboxyl with potassium
71
Properties of alkali ions
Smaller radius higher hydration free energy
72
Mechanisms of rapid rate transport works how?
Due to repulsion of like charges
73
What channels are voltage gated?
Sodium and potassium
74
How are voltage gated ion channels inactivated?
Ball and chain model
75
Acetylcholine receptor are located on what side of the synapse?
Post synaptic
76
How many subunits makes up acetylcholine receptor?
5 subunits
77
What can pass through a gap juntion?
Small hydrophilic molecules and ions(sugars, amino acids, and nucleotides can pass through)
78
What can NOT pass through a gap junction?
Proteins, polysaccharides, and nucleic acids
79
What is the structure of a GAP junction?
12 molecules of connexin make the channel Six connexin make half the channel called connexon 2 connexon form a functional channel
80
Why are gap junctions important
Bones, lens, heart, and labor
81
Where are aquaporins found?
RBC, kidney, cornea | Have 6 transmembrane alpha helixal domains

Biochemistry (9 decks)

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