What's the difference between primary and secondary active transport?
Understand the Problem
The question is asking about the differences between primary and secondary active transport, which are two mechanisms used by cells to transport molecules across their membranes against their concentration gradients. Primary active transport directly uses ATP to move substances, while secondary active transport relies on the electrochemical gradient created by primary active transport to move other substances.
Answer
Primary active transport uses ATP directly, while secondary uses an electrochemical gradient.
Primary active transport directly uses energy (usually from ATP) to move molecules against their concentration gradient. Secondary active transport does not directly use ATP; instead, it relies on the energy stored in the electrochemical gradient created by primary active transport to move molecules against their gradient.
Answer for screen readers
Primary active transport directly uses energy (usually from ATP) to move molecules against their concentration gradient. Secondary active transport does not directly use ATP; instead, it relies on the energy stored in the electrochemical gradient created by primary active transport to move molecules against their gradient.
More Information
Primary active transport is often exemplified by the sodium-potassium pump, which directly uses ATP to move sodium and potassium ions across the cell membrane. Secondary active transport often involves symporters or antiporters, which use the gradient established by primary transport to move other substances.
Tips
A common mistake is thinking that secondary active transport doesn't need energy at all; while it doesn't use ATP directly, it still depends on energy from electrochemical gradients created by primary active transport.
Sources
- Primary and Secondary Active Transport - Biology - Vedantu - vedantu.com
- Active Transport - Khan Academy - khanacademy.org
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