When molecules or ions move across a membrane against a concentration gradient so that they accumulate on one side of the membrane, they do so through Active transport.
- Active transport pumps molecules and ions against a concentration gradient, in contrast to passive transport, which doesn't need energy and moves molecules or ions down a concentration gradient.
- An organism occasionally needs to move something up or down a concentration gradient.
- This can only be accomplished through active transport, which uses ATP (adenosine triphosphate), which is created during cellular respiration.
- Particles pass through a cell membrane during active transport from a lower concentration to a higher concentration.
- The process of pumping molecules and ions across membranes "uphill" – against a concentration gradient – is known as active transport.
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