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Physiology > Cell Transport > Flashcards

Cell Transport Flashcards

1
Q

List some functions of the plasma membrane proteins

A
  • Selective transport of molecules
  • Cell recognition via surface antigens
  • Cell communication (plasma membrane receptors)
  • Tissue organization through adhesion molecules
  • Enzymatic activity
  • Determination of cell shape by linking the cytosceleton to the membrane
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2
Q

List some functions of the plasma membrane lipids

A
  • Transport of molecules
  • Source of second massengers
  • Surface
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3
Q

What are different types of transport through the plasma membrane

A
  • simple diffusion
  • protein-mediated membrane transport
  • vesicular transports
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4
Q

What are examples of protein-mediated membrane transport?

A
  • solute carriers (facilitated diffusion)
  • ATP-dependent carriers (pumps)
  • ion channels
  • water channels
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5
Q

What are examples of vesicular transports?

A
  • endocytosis (pinocytosis, phagocytosis, receptor-mediated endocytosis)
  • exocytosis
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6
Q

What is simple diffusion?

A
  • a form of passive transport that works on the basis of a driving chemical gradient (concentration difference)
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7
Q

What is the mechanism of diffusion?

A
  • random movement of solute due to brownian motion
  • solute (particle) moves to area of smaller solute concentration
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8
Q

How do you measure the net rate of diffusion?

A

Fick’s First Law

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9
Q

What is Fick’s First law?

A

J = DA/ ∆x * ∆c

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10
Q

What do the values of Fick’s First Law stand for?

A

J = net rate of diffusion (in moles per unit time)

D = diffusion coefficient

A = area, across which the diffusion is occuring

∆x= distance

∆c= concentration difference

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11
Q

What properties effect diffusion?

A
  • the driving force (the concentration gradient)
  • thickness
  • O2, CO, CO2, NO, urea, hydrophobic hormones
  • (H2O, ions, glucose)
  • no peptides, no proteins, no disaccharide
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12
Q

What does the rate of diffusion depend on?

A

hydrophobicity and the size of the solute

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13
Q

What are the two types of protein-mediated membrane transport?

A
  • facilitated trasnport
  • active transport
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14
Q

What is facilitated transport?

A
  • passive
  • transport not linked to metabolic energy
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15
Q

What is active transport?

A
  • needs ATP (energy)
  • direct/primary active transport → pump
  • indirect/ secondary active transport → works together with a pump
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16
Q

Protein-mediated membrane transport can be ______ (in regards to number of solute & carried charge)

A
  • uniporter
  • cotransporter: sym/anti
  • electroneutral
  • electrogen
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17
Q

What are properties of facilitated diffusion?

A
  • integral plasma membrane protein mediated
  • more rapid than free diffusion
  • passive (no energy required)
  • driving force is conc. gradient
  • saturation kinetics
  • chemical specificity
  • competition between structurally related molecules
  • specific inhibition
18
Q

What is a water channel?

A
  • passive transport
  • driving force is osmosis
  • water permeability of lipid bilayer is low
19
Q

What is osmosis?

A
  • the flow of water in the direction that intends to dilute the other substance
  • water flows from higher concentration of water to lower
  • water flows from lower concentration of solute (particle) to higher
20
Q

What is osmotic pressure?

A

the minimum pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane

21
Q

How can we calculate osmotic pressure?

A

Van’t Hoff’s Law

22
Q

What is Van’t Hoff’s Law?

A

π = RTnc (see notes for what each letter means)

23
Q

Properties of carriers (enzymes)

A

energy: passive/ active

transport mode: cycle

speed: slow
kinetics: saturation

24
Q

Properties of channels

A

energy: passive

transport mode: gated

speed: fast
kinetic: cannot be saturated

25
Q

How can you classify membrane carriers?

A

by number of solutes: uniporter → cotrasnporter (sum/anti)

energetically: passive or active

carried charge: electroneutral → electrogen

26
Q

What are the units of osmolarity?

A

mOsm/L

27
Q

What are the unites of osmolality?

A

mOsm/kg

28
Q

What is tonicity?

A

the effect of a solution on a cell

29
Q

What happens to the cell volume in the case of an isotonic solution?

A

cell volume does not change

30
Q

What happens to the cell volume in the case of an hypertonic solution?

A
  • cell volume decreases
  • cell shrivels
31
Q

What happens to the cell volume in the case of an hypotonic solution?

A
  • cell volume increases
  • cell swells; lysis
32
Q

What are some examples of cell transports?

A
  1. Glucose transport
  2. Cl- HCO3- exchanger
  3. Na+/ K+ ATPase (Sodium pump)
33
Q

Name some properties of the glucose transport.

A
  • facilitated diffusion
    example: GLUT 1-7 (glucose transporter molecule)
34
Q

What is the function of GLUT 1-7?

A
  • transports glucose from extracellular compartment to intracellular compartment
  • passive transport
  • electroneutral -uniporter
35
Q

What is special about GLUT-2?

A

they can get information about glucose concentration via beta cells

36
Q

What is the function of GLUT-4?

A
  • insulin sensitive transporter

found in: skeletal muscle and adipocytes

37
Q

Name some properties of the Cl-/HCO3- exchanger.

A
  • cotransporter, antiporter
  • passive process
  • electroneutral
  • transports CO2
  • found in: RBC membranes
38
Q

Name some properties of the Sodium pump.

A
  • active transport
  • requires ATP
  • works against chemical gradient
  • electrogenic
  • inhibitor: quabain

3 Na+ IC→EC

2 K+ EC→IC

39
Q

Oncotic pressure

A

type of osmotic pressure of large molecules such as proteins

40
Q

What is relative osmotic pressure?

A

π = RTnc • σ

σ: reflection coefficient

σ = 1 → solute cannot pass (ex. NaCl, sucrose)

σ = 0 → membrane permeable (ex. urea, glucose)

Physiology (28 decks)

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