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MBB 231 > Lecture 7 - Membrane Transport > Flashcards

Lecture 7 - Membrane Transport Flashcards

1
Q

what is the difference between simple diffusion and facilitated diffusion?

A
  • simple diffusion: requires membrane permeability and favourable gradient conditions
  • facilitated diffusion: requires a protein to help get the molecule across the membrane
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2
Q

what is the difference between passive transport and active transport?

A
  • passive transport: down a concentration gradient, no energy needed, transport proteins may or may not be needed
  • active transport: against a concentrations gradient, requires energy input, transport protein “pumps” are required
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3
Q

what is a uniporter?

A

carrier that transports a single solute

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4
Q

what is an antiporter?

A

carrier that transports two solutes in the opposite direction across the membrane

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5
Q

what is a symporter?

A

carrier that transports two solutes in the same direction across the membrane

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6
Q

def: transporter that alternates between two conformations, bind one or more solute molecules, undergoes a conformational change that transfers the solutes to the other side

A

carrier protein

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7
Q

def: water filled pore thorough which specific ions or small molecules can diffuse, form hydrophilic channels through

A

transmembrane channel

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8
Q

def: highly specific channel that can conduct almost a million ions per second, bidirectional, flow determined by electrochemical gradient

A

ion channel

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9
Q

def: passage of a variety of hydrophilic solutes, determined by pore size; some antibiotic resistance has been linked to mutations in certain bacterial porins

A

porin

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10
Q

def: water flows through this channel at a rate of several billion per second, amino acid residues discriminate against other ions of similar size

A

aquaporin

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11
Q

what ions are ion channels normally selective for?

A

Na+, K+, Ca2+, Cl-

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12
Q

def: open and close in response to changes in membrane potential

A

voltage-gated

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13
Q

def: triggered by the binding of specific substances to the channel protein

A

ligand-gated

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14
Q

def: respond to mechanical forces that act on the membrane

A

mechanosensitive-gated

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15
Q

what structural features make a channel a specific to a particular ion?

A
  1. ion specific associations (amino acid side chains and the polar backbone)
  2. constriction in the centre to serve as a size filter
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16
Q

which kind of body cells have aquaporins?

A

specialized cells in the kidney

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17
Q

what does the Glucose transporter GLUT1 do?

A

facilitated diffusion of glucose by a uniport carrier protein

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18
Q

where is GLUT1 found?

A

on all mammalian plasma membranes

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19
Q

GLUT1 process is __________ - can function in either direction depending on the ____________ ________

A

reversible, concentration gradient

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20
Q

T or F: Glucose is rapidly phosphorylated inside the cell which keeps the intracellular concentration of glucose low and this maintains a concentration gradient

A

True

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21
Q

intracellular or extracellular = higher potassium concentration

A

intracellular

22
Q

where is the highest concentration of Ca2+?

A

extracellular

23
Q

where is the highest concentration of Na+?

A

extracellular

24
Q

where is the highest concentration of Cl-?

A

extracellular

25
Q

def: solute accumulation is coupled directly to an exergonic chemical reaction (such as ATP hydrolysis)

A

direct (primary) active transport like ATPases or ATPase pumps

26
Q

what do ATPases do?

A
  • harness the energy of ATP hydrolysis to move ions or small molecules against a concentration gradient/electrical potential
  • active transport
27
Q

where are P type ATPases mostly found?

A

on the plasma membrane

28
Q

which class of P type ATPases are found in all organisms?

A

P1

29
Q

Which classes of P type ATPases are found only in eukaryotes?

A

P2-P5

30
Q

what do P1, P2, P3, P5 transport?

A

cations or heavy metals

31
Q

what does P4 transport?

A
  • lipids
  • acts as a flippase to help maintain membrane asymmetry
32
Q

what do all types of ATPase pumps have in common?

A

they all have one or more ATP binding sites on the cytosolic membrane leaflet

33
Q

P-Type ATPases are members of a large family and are ____________ Phosphorylated by ATP on a specific ____________ acid residue

A

reversibly, aspartic

34
Q

what is most energy consumed by the brain (2/3) used to do?

A

maintain Na+/K+ that maintains the membrane potential required for the transmission of nerve impulses

35
Q

what do V-type ATPase pumps do?

A

pump protons(H+) into organelles

36
Q

what’s an example of a V-type ATPases?

A
  • vacuoles
  • vesicles
  • lysosomes
  • endosomes
  • Golgi complex
37
Q

what are V-type ATPases like structurally?

A
  • 2 multi-subunit components
  • integral component embedded in the membrane
  • peripheral component that juts out from the membrane surface
38
Q

where are v-class proton pumps in animal cells?

A

endosomal and lysosomal membranes

39
Q

what do F-type ATPases do?

A

transport protons in bacteria, mitochondria, and chloroplasts

40
Q

F-type ATPases: __________ flow of H+ up their concentration gradient _______ ATP

A

endergonic, hydrolysis

41
Q

F-type ATPases: _________ flow of H+ down their concentration gradient is used to _________ ATP

A

exergonic, synthesize

42
Q

T or F: can F-type ATPases act in the reverse direction

A

true

43
Q

where are F-type proton pumps found in eukaryotes?

A

inner mitochondrial membrane

44
Q

what does the ABC in ABC type ATPases stand for?

A

ATP binding cassette transporters

45
Q

what were the first kind of ABC type ATPases discovered?

A

importers, involved in the uptake of nutrients

46
Q

what do all ABC type ATPases have?

A
  • 2 nucleotide (ATP) binding domains
  • 2 transmembrane domains
47
Q

why are ABC transporters medically important?

A

some of them pump antibiotics or drugs out of cells and render the cell resistant to the drug

48
Q

tumours that are resistant to growth inhibiting drugs have a high concentrations of what kind of transporter?

A

ABC transporter: MDR transport protein

49
Q

unlike most ABC transporters, MDR protein transports a _______ ______ of ________ ________ drugs

A

wide range of chemically dissimilar drugs

50
Q

T or F: Does indirect active transport rely on ATP ?

A

Yes, because the Na+ or H+ concentration gradient necessary for this process is generated by ATPase pump

51
Q

in co transport, can a molecule move on its own?

A

no, the favoured reaction is coupled with the unfavourable reaction in order to drive the unfavourable reaction against a concentration gradient

MBB 231 (19 decks)

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