BIO MODULE 3:Set 4 — Active Transport, Pumps & Cotransport

What is active transport?

Movement of substances across a membrane against their concentration gradient using energy.

Does active transport require energy?

Yes, either directly or indirectly.

Does active transport move substances with or against their concentration gradient?

Against their concentration gradient.

What are three key features of active transport?

It requires membrane transport proteins, is specific for certain substances, and can become saturated.

What are the two types of active transport?

Primary active transport and secondary active transport.

What is primary active transport?

Transport in which a membrane protein directly hydrolyzes ATP to power movement of substances.

What is secondary active transport?

Transport that uses the energy stored in a favourable ion concentration gradient to move another substance.

What is the major difference between primary and secondary active transport?

Primary active transport directly uses ATP; secondary active transport uses an ion gradient established using energy.

What does ATP hydrolysis mean?

The breakdown of ATP that releases energy for cellular processes.

What are three examples of primary active transport pumps?

H+ pumps, Ca2+ pumps, and Na+/K+ pumps.

What is another name for an H+ pump?

A proton pump.

What is the function of the Na+/K+ pump?

It moves sodium ions out of the cell and potassium ions into the cell using ATP.

Which ion does the Na+/K+ pump move OUT of the cell?

Sodium (Na+).

Which ion does the Na+/K+ pump move INTO the cell?

Potassium (K+).

What provides the energy for the Na+/K+ pump?

ATP hydrolysis.

In what type of cells is the Na+/K+ pump particularly important?

Animal cells.

What provides energy for secondary active transport?

A favourable concentration gradient of ions.

What is a symporter?

A transport protein that moves two different substances in the same direction across a membrane.

What is an antiporter?

A transport protein that moves two different substances in opposite directions across a membrane.

What is the main difference between symport and antiport?

Symport moves substances in the same direction; antiport moves them in opposite directions.

What is cotransport?

A process where primary active transport creates a gradient that indirectly drives the transport of another solute.

How are primary and secondary active transport connected?

Primary active transport establishes an ion gradient that secondary active transport can use.

What ion gradient is commonly used for cotransport in plants?

A hydrogen ion (H+) gradient.

What creates the hydrogen ion gradient used in plant cotransport?

Proton pumps.

What nutrient is used as an example of cotransport in plants?

Sucrose.

How can sucrose enter plant cells through cotransport?

H+ moves down its gradient through a cotransporter, providing energy to move sucrose into the cell.

Why is secondary active transport considered active even though ATP is not directly used by its transporter?

Because it indirectly depends on energy used to establish the ion gradient.