5.4 Active transport

Question 1

Active transport

Answer 1

movement of molecules or ions into or out of cell from a region of low concentration to region of higher concentration
–> requires energy and carrier proteins

Question 2

Active transport on a membrane (outside to inside cell)
–> carrier protein

Answer 2

1. Molecule or ion to be transported binds to receptors in channel of carrier protein on the outside of cell
2. On the inside of cell ATP binds to carrier protein & is hydrolysed into ADP and phosphate
3. Binding of phosphate molecule to carrier protein causes protein to change shape (opens up)
4. Molecule/ ion is released to inside of cell
5. Phosphate molecule is released from carrier protein & recombines to form ATP
6. Carrier protein returns to normal shape

Question 3

Bulk transport

Answer 3

another form of active transport
–> large molecules like enzymes or hormones are too large to fit through channel/ carrier proteins

Question 4

Endocytosis? how does it work?

Answer 4

bulk transport of materials into a cell
1. Cell-surface membrane invaginates when in contact with material
2. Membrane enfolds the material until a vesicle is formed
3. The vesicle punches off an moves into the cytoplasm to transfer the material

Question 5

Phagocytosis and pinocytosis

Answer 5

phago: bulk transport of solid materials into a cell

Pino: bulk transport of liquid
materials into a cell

Question 6

Exocytosis

Answer 6

bulk transport of materials out of a cell
–> vesicles formed from the Golgi apparatus move towards and fuse with the cell-surface membrane (contents are released)