Membrane Transport Proteins

Question 1

Nomenclature Committee Database that makes sure that each symbol is unique, and ensures that each gene locus is only given one approved gene symbol

Answer 1

Human Genome Organization (HUGO)

Question 2

Transport proteins can be classified into two groups

Answer 2

Carriers and Channels

Question 3

Channels can be classified into 4

Answer 3

Alpha-helical protein channels
Beta-barrel protein porins
Toxin channels
Peptide channels

Question 4

Carriers can be classified into 4

Answer 4

Primary Active Transporters

Electrochemical Potential-Driven Porters

Group translocators and Other Transporters / Carriers Permeases

Question 5

Transport substances w/o stereospecific binding of the substance through facilitated diffusion

Answer 5

Channels (including pore proteins)

Question 6

Transport substances w/ stereospecific binding of the substance through facilitated diffusion or active transport

Answer 6

Carriers (including permeases and translocators)

Question 7

Differentiate Channels and Carriers

Answer 7

Channels are like a hallway.
Carriers are like a selective revolving door.

Question 8

Transport ions across a membrane

Answer 8

Ion channels

Question 9

4 types of ion channels

Answer 9

Voltage-gated
Ligand-gated (extracellular and intracellular)
Stress-gated

Question 10

Channels that allow movement of water across the membrane at a faster rate

Answer 10

Water channels/Aquaporin

Question 11

Are water channels active or passive transport? Why are they still needed?

Answer 11

Passive transport, to allow faster equilibriation of water.

Question 12

T/F an ion channel can only be one type (i.e. ligand gated only or voltage gated only)

Answer 12

False, it can be both. For example the NMDA ion channel needs the ligand glutamate and the right voltage to remove Magnesium and let molecules pass through

Question 13

Use carrier-mediated process to catalyze transport

transport by facilitated diffusion or by the use of chemiosmotic energy but NOT ATP or other nucleoside triphosphate

Answer 13

Porters

Question 14

Three types of porters? Differentiate

Answer 14

Uniporter, Symporter, and Antiporter
Uniporter transports on ion only
Symporter transports two ions in the same direction
Antiporter transports two ions in the opposite direction

Question 15

Uniporter
- crucial for providing constant supply of glucose for energy-yielding metabolism
- allows facilitated diffusion of glucose into erythrocytes
- integral protein with 12 membrane-spanning segments

Answer 15

Glucose Transporter (GLUT1)

Question 16

Antiporters that allows very rapid movement of HCO3- cross the erythrocyte membrane

Uses an antiport mechanism to mediate exchange of HCO3- ion with Cl- ion

Answer 16

Anion exchanger (Chloride-Bicarbonate Exchanger)

Question 17

hydrolyze ATP as energy source to actively pump substances across the membrane

Answer 17

Transport ATPases

Question 18

Animal cells maintains high ____and low ____ concentration (compared to external surroundings).
This is made possible by the sodium potassium pump

Answer 18

High Potassium (K+) and low Sodium (Na+)

Question 19

Main example of P-type Active Transporter (P-type = Found in plasma membrane)

Answer 19

Sodium-Potassium Pump

Question 20

What are V-type ATPases? What is the main example of this?

Answer 20

Vacuolar Active Transporters, found in the vacuole.
Proton (H+) Pump to maintain acidity in vacuoles

Question 21

What are F-Type classes of ATPases?

Answer 21

Active transporters that can use passive transport to synthesize ATP. Basically it can use or make ATP dependent on what direction it will transport material to. If against the gradient, it will use ATP, if along, it can make ATP

Question 22

A special transport protein for large molecules (>40kDa) that allows them to pass through a channel for small molecules. Unclassified because it is free floating, no specified location. (Analogy: ID pass that lets them go through small channels)

Answer 22

Nuclear Pore Complex

Question 23

__________ requires GTP hydrolysis to transfer Nuclear Exportation and Localization signals. GTP Removes the cargo so that ___________ can go back to get more cargo

Answer 23

Importin and Exportin