BioE Sig: Active Transport, ATP Pumps Flashcards
What is active transport?
The movement of molecules or ions across a membrane against their concentration gradient (“uphill”), requiring energy.
Why does active transport require energy?
Because it moves substances against their concentration gradient (low to high).
What are the two types of energy sources for active transport?
Metabolic ATP breakdown (direct ATP use).
Ion gradient utilization (indirect use of pre-existing gradients).
What does “moving a molecule uphill” mean in the context of active transport?
It refers to transporting molecules from a low concentration area to a high concentration area, requiring energy input.
What is a substrate in active transport?
A molecule or ion that needs to be transported across the membrane.
What determines the binding specificity of a transporter?
The residue sequence (amino acid sequence) of the transporter.
What is meant by “lock and key” in active transport?
Transporters have specific affinity for certain molecules, meaning only the correct molecules can bind and be transported.
How do inhibitors affect active transport?
- Competitive inhibitors bind to the transporter’s active site, blocking substrate binding.
- Non-competitive inhibitors bind elsewhere on the transporter, changing its shape and function.
What is the difference between competitive and non-competitive inhibitors?
-Competitive inhibitors block the active site.
-Non-competitive inhibitors bind elsewhere and change the transporter’s function.
What is a uniporter?
A transporter that moves only one solute in one direction
What is a symporter (co-transporter)?
A transporter that moves two solutes in the same direction.
What is an antiporter (exchanger)?
A transporter that moves one solute in one direction while moving another solute in the opposite direction.
How do symporters and antiporters differ?
-Symporters move two substances in the same direction.
-Antiporters move two substances in opposite directions.
What defines primary active transport?
It directly uses ATP to move substances against their concentration gradient.
How does ATP contribute to primary active transport?
ATP hydrolysis (breaking down ATP) provides the energy needed for transport.
What is an example of primary active transport?
Na⁺/K⁺ ATPase (sodium-potassium pump).
What is the function of the Na⁺/K⁺ ATPase pump?
Pumps 3 Na⁺ out of the cell and 2 K⁺ into the cell, maintaining the electrochemical gradient.
Why is the Na⁺/K⁺ ATPase important for cells?
Maintains cell volume, membrane potential, and ion homeostasis.
Does primary active transport move substances with or against their concentration gradient?
Against (low to high concentration).
How does secondary active transport differ from primary active transport?
Secondary active transport does not directly use ATP but relies on an existing ion gradient created by primary active transport.
What type of energy does secondary active transport use?
Electrochemical gradient energy, stored from ion movement.
How does ATP contribute to secondary active transport?
ATP is not directly used but sets up the ion gradient that drives transport.
What is an example of secondary active transport?
Glucose-Na⁺ symporter, which uses the Na⁺ gradient to bring glucose into the cell.
Why is secondary active transport still considered “active” transport?
Because it requires energy indirectly through ion gradients.
