Understanding Integral and Peripheral Proteins: Biology Q&A

[bengalkitties]

Proteins associated with the plasma membrane can be classified as either integral membrane proteins or peripheral membrane proteins. For the following types of proteins, please specify whether they would be integral or peripheral.
Glucose transporter
Sodium-potassium pump
Ion channel

-I think that peripheral membranes are only on one side of the membrane whereas integral proteins are on both sides of the membrane. Therefore, I thought that glucose transporter was integral, sodium potassium was integral, and ion channel was peripheral. What am I doing wrong?

MY NEXT QUESTION:
Transport of large or hydrophilic molecules across the plasma membrane can occur via facilitated diffusion or via active transport. For the following types of proteins, please indicated which type of transport is involved.

Ion channel
Glucose transporter GLUT-1
Sodium-potassium pump

Active transport is when molecules can cross against the concentration gradient whereas faclitated diffusion can't go across the concentration gradient. So this is what I did: for ion channel, I said faclitated diffusion, glucose transporter is active transport, and sodium potassium pump is active transport. Where am I going wrong?

Any help would be appreciated! Thanks.

 

[Ygggdrasil]

Hints are available on another site:

http://www.chemicalforums.com/index.php?topic=28611.0

 

[Blueshift5]

I would like to clarify that the classification of proteins as integral or peripheral is based on their physical association with the plasma membrane, not their function. Integral proteins are embedded within the membrane, while peripheral proteins are only temporarily associated with the membrane. Therefore, the correct classification for the proteins mentioned would be:

Glucose transporter - Integral protein
Sodium-potassium pump - Integral protein
Ion channel - Integral protein

For the second question, the type of transport involved is determined by the energy requirement for the movement of molecules. Active transport requires energy (usually in the form of ATP) to move molecules against the concentration gradient, while facilitated diffusion does not require energy and moves molecules along the concentration gradient. Therefore, the correct classification would be:

Ion channel - Facilitated diffusion
Glucose transporter GLUT-1 - Facilitated diffusion
Sodium-potassium pump - Active transport

I hope this clarifies any confusion. It is important to understand the difference between the physical association of proteins with the membrane and their function in transport processes.