Active transport Flashcards
What is active transport?
Active transport is the movement of molecules from a region of lower concentration to a region of higher concentration. The particles move against the concentration gradient, using energy released from ATP and carrier proteins.
Describe the process of active transport across membranes
The molecule/ ion to be transported binds to the receptor of the carrier protein
ATP binds to the carrier protein and is hydrolysed to ADP and phosphate
This causes the carrier protein to change shape
Molecule or ion is released into the cell
The phosphate molecule rejoins back with ADP to form ATP
The carrier protein returns to its original shape
Why is the process selective?
Specific substances are transported by specific carrier proteins
What is bulk transport?
Transport for molecules that are too large to move through the membrane via proteins (eg enzymes, hormones)
What is endocytosis
A type of bulk transport- bringing substances into cells
Phagocytosis- solids
Pinocytosis- liquids
What is exocytosis
A type of bulk transport- taking substances out of cells
Vesicles formed by the golgi apparatus move towards and fuse with the cell membrane, which is then released outside the cell.
Where is energy (in the form of ATP) required?
- Movement of vesicles along the cytoskeleton
- Changing the shape of carrier proteins
