Cells - Transport across membranes: Active Transport Flashcards
Define 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 ATP and carrier proteins.
In what direction are substances moved through active transport?
Against a concentration gradient.
What form of energy is required for active transport?
Metabolic energy in the form of ATP
What type of proteins are used in active transport?
Carrier proteins
Describe direct active transport
1) A specific molecule/ion binds to receptor sites on carrier protein spanning the plasma membrane
2) On the inside of the cell/organelle, ATP binds to the protein causing it to split into ADP and phosphate
3) The carrier protein changes shape and opens to the opposite side of the membrane
4) The molecule/ion is released to the other side of the membrane
5) The phosphate molecule is released from the protein
6) The carrier protein reverts to its original shape
7) The phosphate molecule recombined with the ADP to form ATP during respiration
How many molecules/ions are transported at a time during direct active transport?
One
How many molecules/ions can be trasnported at a time in cotransport and in what direction?
Multiple in the same direction
What is cotransport?
A form of active transport where molecules are moved individually using a concentration gradient already set up by direct active transport.
What are cotransporters?
A type of carrier protein
How does cotransport work?
The concentration gradient of one of the molecules is used to move the other molecule against its own concentration gradient.
Give an example of cotransport
The sodium potassium pump
How does the sodium potassium pump work?
Sodium ions move into the cell down their concentration gradient. This moves glucose against its concentration gradient, into the cell.
What is indirect active transport?
Active transport that is not powered by ATP directly.
Give an example of indirect active transport
Cotransport e.g of glucose into the ileum
