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23 Nov 2019

Which of the following statements correctly distinguishes transporters from porins and on channels?

A. Transporters exhibit a conformational change when the substrate binds but porins and ion channels do not.

B. Porins and ion channels have a permanent hole that passes from one side of the membrane to the other through which solutes pass whereas transporters do not.

C. Porins and ion channels mediate passive transport, while transporters are associated with both passive and active transport.

D. Both A and B are correct

E. All of the above are correct

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Related questions

1. Which of the following pairings are/is correct?

Cholesterol: has a hydrophilic and hydrophobic end
Cholesterol: does not have a hydrophilic end since it is a lipid
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2. Which of the following pairing/s is/are correct?

Cholesterol: helps maintain the integrity of the cell membrane
Cholesterol: the rigid four carbon rings prevent lipid tails from packing too closely
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3. Which of the following pairing/s is/are correct?

Membrane proteins: help maintain concentration gradients
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Solutes: are the substances dissolved in a solution
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4. Which of the following pairing/s is/are correct?

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5. Which of the following pairing/s is/are correct?

Passive movement: movement of molecules that is energetically favorable b/c free energy is released in the process
Passive movement: requires energy from outside of the system
Passive movement: occurs as molecules move up their concentration gradients
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6. Which of the following pairings/s is/are correct?

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Active movement: is an energetically unfavorable process
Active movement: releases free energy
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7. Which of the following pairing/s is/are correct?

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8. Which of the following paring/s is/are correct?

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azurewallaby690

1 Which of the following statements is false?

(a) CO₂ and O₂ can diffuse freely across the cell membranes.

(b) The differences in permeability between artificial lipid bilayers and cell membranes arise from variations in phospholipid content.

(d) Cells expend energy in the form of ATP hydrolysis to maintain ion concentrations that differ from those found outside the cell.

2 Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell?

(a) Na⁺

(b) K⁺

(d) Cl^â

3 Pumps are transporters that are able to harness energy provided by other components in the cells and drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________.

(a) active transport.

(b) free diffusion.

(d) passive transport.

harlequinbuffalo618

1. What biochemical feature of a phospholipid molecule allows phospholipids to spontaneously form closed compartments when placed in an aqueous solution?

a) they are amphipathic

b) they are charged

c) they are spherical

d) they have a single fatty acid tail

2. Other than phospholipids, what molecule do cells use to alter the fluidity of biological membranes?

3. What distinguishes active transport from passive transport?

a) active transport can utilize channel proteins

b) passive transport does not utilize carrier/transporter proteins

c) active transport requires the input of energy

d) active transport only occurs at the plasma membrane

4. In the case of active transport, the Na+/K+ pump undergoes a sequence of conformational changes that allows the movement of Na+ and K+ across a membrane against their electrochemical gradients, while in the case of ER protein import SRP undergoes a sequence of conformational changes to allow the signal sequence to interact with the translocation pore. What drives these conformational changes?

a) hydrolysis of a high energy phosphate bond

b) binding of a solute or protein

c) both

d) neither

5. Is protein import into the ER co-transcriptional, or co-translational?