3- Active Transport

What does active transport allow cells to do?

Exchange molecules against a concentration gradient.

What does active transport cause there to be on the different sides of the cell surface membrane of a cell?

A different environment.

In what form is the metabolic energy needed for active transport provided?

ATP (adenosine triphosphate).

How does active transport differ from passive forms of transport?

ATP is required, materials are moved against a concentration gradient, carrier proteins acting as pumps are involved, specific substances are transported (a selective process).

How is active transport different to facilitated diffusion?

Although both use a carrier proteins, however facilitated diffusion moves down a concentration gradient rather than against one like active transport, so it doesn't require metabolic energy.

How does active transport use ATP?

Directly in order to move molecules, or by using a concentration gradient already set up by direct active transport (co-transport).

What is the sodium-potassium pump import to?

Many important processes within the body, for example the creation of nerve impulses.

What does active transport require?

Metabolic energy in the form of ATP (adenosine triphosphate).

How are molecules prevented from leaking back out of a cell once actively transported inside?

The barrier formed by the cell-suface membrane's phospholipid bilayer, which is only capable of transporting lipid soluble substances across.

What is active transport?

The movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using energy and carrier molecules.

What happens to ADP and the phosphate molecule once the molecules or ions in direct active transport have moved across the membrane? What does this cause?

The phosphate molecule is released from the protein and recombines with the ADP to form ATP again, causing the protein to change back to it's original shape.

In direct active transport, how do the molecules or ions move across the cell-surface membrane?

They bind to receptors on the channels of the carrier protein. Inside the cell, ATP binds to the protein so it splits into ADP and a phosphate molecule, so the protein changes shape so the molecules or ions can travel to the other side of the membrane.

In direct active transport, what role do carrier proteins play?

They span the cell surface membrane and accept the molecules or ions being transported.

What is the sodium-potassium pump an example of?

When more than one molecule or ion is transported by active transport into a cell (in this case potassium ions) while another is moved by active transport out of a cell (in this case, sodium ions).

Can more than one molecule or ion be transported at the same time in different directions using active transport?

Yes.

Can more than one molecule or ion be transported in the same direction at the same time by active transport?

Yes.