Symport versus Antiport
Learning Objective
I can compare and contrast symport and antiport mechanisms in cellular co-transport.
Key Concepts
In secondary active transport, one ion moves down its concentration gradient, causing another ion or molecule to move against its gradient.
Symport (or co-transport) means that both solutes move in the same direction, while antiport (or counter-transport) means the solutes move in opposite directions.
In the sodium-glucose co-transport example, sodium moves from a high to low concentration, creating the energy to drive glucose from a low to high concentration.
Practice Questions
This lesson includes 3 practice questions to reinforce learning.
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1. Explain the fundamental difference between symport and antiport mechanisms in secondary active transport. Focus on the direction of solute movement.
2. In secondary active transport, what is the primary driving force that enables another solute to move against its concentration gradient?
3. Imagine a cell where sodium ions are at a higher concentration outside the cell than inside. A new molecule, substance 'Z', is transported into the cell along with sodium. Substance 'Z' is found to have a higher concentration inside the cell than outside. Based on this information, is the transport of substance 'Z' an example of symport or antiport? Explain your reasoning.
Educational Video
Human Physiology - Secondary Active Transport
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