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Biochemistry > [2] class3 Zaidi-transport Thru Membranes > Flashcards

[2] class3 Zaidi-transport Thru Membranes Flashcards

1
Q

Interactions involved in lipid bilayer:

A

Electrostatic and non covalent

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2
Q

These are frequently glycosylated on the extracellular side of the lipid bilayer

A

Membrane lipids and proteins

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3
Q

Integral membranes

A

All the way transmembrane through lipid bilayer

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4
Q

Plasma membrane is semi

A

Semi-permeable

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5
Q

________facilitate movement of specific molecules across the Plasma membrane

A

Membrane transport proteins

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6
Q

Several hydrophobic residues for one protein the enters and leaves PM several times:

A

polytopic

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7
Q

Most transport proteins are:

A

Polytopic transmembrane integral membrane proteins

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8
Q

What is advantage to polytopic membrane proteins?

A

Allows more diversity in binding and conformational changes

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9
Q

What is permeable to PM??

A

Lipophilic molecules via diffusion - steroid hormones

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10
Q

What is impermeable to the PM?

A

Hydrophilic/ polar substances

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11
Q

How can polar/hydrophilic molecules pass through PM?

A

Needs a specific transport mechanism

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12
Q

What is used for specific transport of molecules across PM?

A

Membrane proteins

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13
Q

Polytopic, transmembrane, integral membrane proteins can:

A

Have multiple transport domains and can shape the cell to allow more substances to pass

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14
Q

What determines the ionic composition of the cell?

A

The activity and protein levels of specific transporters

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15
Q

What governs the biochemical/metabolic characteristics of a cell?

A

Expression of specific transporters

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16
Q

One way of regulating metabolism

A

Alteration in expression levels of transporters

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17
Q

Ion gradient are they static?

A

No dynamic, but they could be thought of static in regard to they are quickly reestablished [in the way they’re maintained]

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18
Q

Ion gradient allows for:

A

Membrane potential for AP

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19
Q

Brains uses _____ of energy

A

20%

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20
Q

Molecules move down a [ ] gradient by using energy stored in the gradient: Ex:

A

Passive transport ; ion channels

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21
Q

Molecules move against a gradient by using biochemical energy stored in ATP: EX:

A

Active transport; pumps/ ATPases

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22
Q

Energy independent movement of molecules down a gradient:

A

Passive transport

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23
Q

2 types of passive transport :

A

Simple diffusion

And

Facilitated diffusion

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24
Q

Molecules that are small, nonpolar, and uncharged move freely across PM unaided

A

Simple diffusion

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25
Q

Molecules that’re large and charged unable to cross the PM w/o assistance of channel or transporter

A

Facilitated diffusion

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26
Q

____________ of molecules is asso. W. free energy

A

Unequal distribution

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27
Q

What is used to set up an ion gradient across a semi-permeable membrane?

A

Energy

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28
Q

Ion gradients are generated by:

A

Membrane transporters [energy transducers]

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29
Q

Membrane transporters use energy from and store it as free energy of the gradient

A

ATP

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30
Q

Energy is minimum when [ ] across a semi-permeable mebrane is:

A

Equal

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31
Q

Positive free energy =

A

Active transport

32
Q
  • free energy =
A

Spontaneous

33
Q

Movement of molecules against a gradient

A

Energy-dependent movement

34
Q

2 diff. Types of proteins involved in energy-dependent movement:

A

P type ATPases

ATP binding cassette transporters

35
Q

Ex of P type ATPases

A

Na+K+ ATPase
PM Ca++ ATPase [PMCA]
Muscle Ca++ ATPase SERCA
H+ K+ ATPase

36
Q

Ex of ATP binding cassette transporter:

A

Multi-drug resistance protein

37
Q

Uses energy from ATP hydrolysis to drive transport against gradient

ATP breaks into ADP and phosphate
Transporter forms covalent bond w/ phosphate to form EP intermediate

A

P type ATPases

38
Q

Makes neurons and muscle cells electrically excitable, controls cell volume, drives the active transport of sugars and amino acids

25-40% of brain ATP used by

3Na+: 2K+ / mole ATP

A

Sodium pump

39
Q

Ex of Na pump

A

Plant steroids- digitoxigenin and ouabain

40
Q

called cardiotonic steroids d/t strong effect on heart

A

digitoxigenin and ouabain

41
Q

Mixture of cardiotonic steroids

42
Q

Cardiac glycosides that inhibit Na+K+ ATPase activity

A

ouabain and digitoxigenin

43
Q

How does Digitoxigenin and ouabain work:

A
  • Increase Na+ levels in cell: this reduces activity of antiporter Na+Ca++ exchanger
  • This increase Ca++ ICF
  • This Ca+ increases contractile force of cardiac muscle
44
Q

Ex of Ca++ pumps:

A

Plasma mebrane Ca++ ATPase- PMCA

Sarco-endoplasmic reticulum Ca++ ATPase- SERCA

45
Q 
A protein w/ 10 transmembrane 
140kDa
Transports Ca++ from cytosol to extracellular 
Maintains 10,000-fold gradient across PM
Uses ATP to pump Ca+ uphill
46
Q

Stimulated by the Ca+ binding protein calmodulin (CaM)

47
Q

Zaidi research

A

Structure of PMCA

48
Q

Active site of CaM

A

ATP binding site

49
Q

PMCA ex:

A

[CaM] calmodulin

50
Q

Ca++ transport channel open when active or inactive?

51
Q 
10 transmembrane domains 
110 kDa
Transports Ca+ from cytosol to ER
80% of SR membrane protein
Uses ATP
Plays role in relaxation of contracted muscle
52
Q

Key characteristic of Ca+ pumps SERCA and PMCA

A

Conformational change

53
Q

Human genome has 150 genes
Have common architecture
Multi-drug resistance protein/ P glycoprotein
Pump wide range of small molecules out of cells
Uses ATP as energy source

A

ABC transporters

54
Q

ATP binding domain is typically

A

In cytosol

55
Q

Does ABC transporters have conformational change?

56
Q

What happens to ATP affinity when substrate binds?

57
Q

Active transport mediators not directly driven by ATP
Thermodynamically unfavorable flow of one species of ion against gradient coupled to favorable flow of another species down gradient

A

Secondary transporters

58
Q

Ions move in opposite direction

A

Antiporters

59
Q

Ions move in same direction

A

Symporters

60
Q

Ions can move in both directions, depending upon the [ ]

61
Q

Ex of antiporter

A

Sodium calcium exchanger

62
Q

Ex of symporter

A

Lactose permease

63
Q

Ex of uniporter

A

Mitochondrial Ca+ transporter

64
Q

Uses a proton gradient generated by oxidation of fuel molecules to drive lactose and other sugars against [ ] gradient

Is a symporter

A

Lactose permease

65
Q

Steps of lactose permease:

A 
1-H+ out
2-lactose out
3-EVERSION
4-lactose in
5- H+ in
6-EVERSION
66
Q

Polytopic membrane proteins are often:

A

Transporters

67
Q

What 2nd structure are proteins that make up polytopic transport proteins in membrane

68
Q

Sodium pump _____ and K+ pumps in ______

69
Q

uses ATP to change conformation for action to occur

A

Ptype atpase

70
Q

If + ∆G what type of transport

A

Active transport

71
Q

If -∆G what transport:

A

Passive: simple or facilitated diffusion

72
Q

Why is P type called P type ATPase?

A

P=phosphate covalently bonded to protein during process that req’s energy.

Ex: SERCA Na+/K+ pump / PMCA

73
Q

Where does (Pi) phosphate bind on P type ATPase?

A

Aspartate residue

74
Q

Inhibit the dephosphorylation of E2P state of the Na+/K+ pump

75
Q

ATP binds to this point________ causing the active for of PMCA

A

btw 4 and 5 transmembrane domains

76
Q

Abc transporter

77
Q

What position SERCA bind a phosphate thus activating its Ca++ transport capabilities

Biochemistry (13 decks)

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