Membrane Proteins and Transport Functions Quiz

Which type of transport involves the movement of molecules in the direction determined by their relative concentrations inside and outside of the cell?

Facilitated diffusion

What is the main difference between passive diffusion and facilitated diffusion?

Facilitated diffusion involves the movement of molecules through membrane proteins, while passive diffusion does not

Which type of transporter enables large and polar (charged) molecules to cross the membrane without directly interacting with its hydrophobic interior?

Carrier

Which type of active transport uses energy or a gradient generated by another active transporter?

Secondary active Signup and view all the answers

Which type of transporter transports only one molecule?

Uniporter Signup and view all the answers

Which type of active transport is driven by a gradient that was generated by a primary active transporter?

Primary active Signup and view all the answers

Which of the following is NOT a characteristic that affects the permeability of molecules?

Cell size Signup and view all the answers

Which of the following is NOT an example of a common membrane protein?

DNA polymerase Signup and view all the answers

What is the main difference between ion channels and transport proteins?

Ion channels transport ions while transport proteins transport molecules Signup and view all the answers

How are channels activated?

By changes in membrane potential Signup and view all the answers

What is the process of facilitated diffusion?

Movement of molecules with the help of transport proteins Signup and view all the answers

What are the three types of active transport?

Primary, secondary, and tertiary Signup and view all the answers

Which state of a transporter exposes the binding sites for solutes to the outside?

Outward-open state Signup and view all the answers

Which type of transport occurs spontaneously by diffusion and does not require energy?

Passive transport Signup and view all the answers

What is the main difference between active transport and passive transport?

Active transport occurs against a concentration gradient, while passive transport occurs down a concentration gradient Signup and view all the answers

What happens during simple diffusion?

Molecules dissolve in the aqueous solution at the other side of the membrane Signup and view all the answers

Which state of a transporter exposes the binding sites for solutes to the inside?

Inward-open state Signup and view all the answers

What is the main characteristic of active transport?

It requires energy Signup and view all the answers

Which type of membrane proteins interact with solutes more weakly compared to transporters?

Channels Signup and view all the answers

What is the function of aquaporins?

Facilitate osmotic water flow Signup and view all the answers

Which ion cannot be successfully accommodated in the selectivity filter of a channel?

Na+ Signup and view all the answers

What is the main function of the Na+/K+-ATPase in animal cells?

Maintain Na+ and K+ concentration differences Signup and view all the answers

Which type of membrane protein binds a specific substrate to be transported and undergoes conformational changes to transfer the solute across the membrane?

Transporters Signup and view all the answers

In which type of cells are aquaporins expressed on the plasma membrane to make water movement more efficient?

Cells that reabsorb high volumes of water Signup and view all the answers

Which of the following is true about membrane transport proteins?

They make up 15-30% of all membrane proteins Signup and view all the answers

What restricts the passage of most polar molecules across the lipid bilayer?

The hydrophobic interior of the lipid bilayer Signup and view all the answers

What is the result of an active transport and passive diffusion in maintaining the resting membrane potential of cells?

A slight deficit of positive ions on one side of the membrane Signup and view all the answers

What is the electrochemical gradient of a charged solute influenced by?

The membrane potential Signup and view all the answers

How do transporters typically span the plasma membrane?

Through multiple alpha helices Signup and view all the answers

What are the common structural features of transport proteins?

They can work in both inward-open and outward-open conformations Signup and view all the answers