Membrane Transport III (Lecture 11)

Question 1

How do you measure membrane potential?

Answer 1

Microelectrode filled with a conducting fluid (KCl solution) inserted into a cell in such a way that the plasma membrane seals itself around the tip of the electrode

Question 2

True or False: Animal cell resting membrane potential depends largely on outward flow of K+ ions through open K+ channels

Answer 2

True

Question 3

How do channels make sure that only ‘their’ ion is allowed through the membrane?

Answer 3

Selectivity filter

Question 4

______ is made up of alpha-helices of the pore segment (P-helix) have extended loops that govern ion selection

Answer 4

Selectivity filter

Question 5

As ions are passing through channel, they lose _______ molecules and interactions are with ______ oxygens of the filter.

Answer 5

H20, carbonyl

Question 6

The animal cell plasma membrane resting potential is generated by the ATP-powered _______ and ______.

Answer 6

Na+/K+ pump

nongated K+ channels

Question 7

Why is Na+ a good ion to power the uphill

movement of other molecules?

Answer 7

—Na+ gradient established by Na+/K+-ATPase (P-class pump)
—
Na+ re-entry into mammalian cells down its concentration gradient is thermodynamically favored

Na+ movement across the plasma membrane – governed by the sum of two distinct forces acting in same direction

Question 8

True or False GLUT transport

glucose down its concentration gradient and is useful when [Glucose]extracellular > [Glucose]cytosol

Answer 8

True

Question 9

True or False: Na+-linked symporters enable animal cells to import glucose and amino acids against high concentration gradients

Answer 9

True

Question 10

What is the best example of a symport mechanism?

Answer 10

Na+/amino acid

Question 11

______ transport is the two-stage movement of molecules through a cell

Answer 11

Transcellular

Question 12

Transcellular transport is ______ through the apical membrane ______ through the basolateral membrane

Answer 12

import, export