Active Transport

Question 1

What is active transport?

Answer 1

• In active transport (aka active carrier mediated transport) carrier proteins use energy from ATP (adenosine triphosphate) to move substances from low concentration to high concentration
  
  • It is an active process
• In active transport, the substance binds to a carrier protein. The molecule ATP then also binds to the carrier protein and is converted to ADP (Adenosine diphosphate) releasing energy in the process.
• This energy causes the carrier protein to change shape, and move the substance across the cell membrane
• Certain ions such as sodium ions (Na+) are transported via active transport.

Question 2

Vesicular transport (active process)

Answer 2

• In vesicular transport, energy is used to move enclosed vesicles containing substances such as water or enzymes into or out of the cell
• It may go from either high –> low concentration or low –> high

Question 3

Exocytosis (active process)

Answer 3

• When vesicles are used to remove substances it is termed exocytosis
• A vesicle that is formed inside the cell migrates to the cell membrane and fuses with the membrane. The contents of the vesicle are then pushed out into the extracellular fluid.
• Secretions such as mucus and digestive enzymes are transported via exocytosis

Question 4

Endocytosis (active process)

Answer 4

• When vesicles are used to bring substances into the cell, it is termed endocytosis.
• The cell membrane folds around a droplet of liquid or a solid particle until the droplet or particle is completely enclosed. The vesicle formed then pinches off and is suspended in the cell’s cytoplasm
• Endocytosis involving liquids is termed pinocytosis, solids is termed phagocytosis