3.4 - Active Transport
What active transport is
- Active transport is the movement of particles across a cell membrane against a concentration gradient - from an area of lower concentration to an area of higher concentration.
- It requires energy transferred by respiration to make it happen.
Active transport is the opposite of diffusion
- In diffusion, particles move down the concentration gradient on their own, and no energy is needed.
- Active transport moves particles the other way - up the gradient - so it cannot happen by itself.
- It has to be driven by energy from respiration. This energy is carried by a molecule called ATP, which the cell uses to power the transport.
Carrier proteins do the moving
- Carrier proteins are embedded in the cell membrane.
- They pick up the particles on one side and move them across to the other side, against the gradient.
TermDefinition
Active transportThe movement of particles across a cell membrane against a concentration gradient (from a lower to a higher concentration), using energy transferred by respiration.
ATPA molecule that carries energy to the parts of a cell that need it, made using energy from respiration (or from light in photosynthesis).
Carrier proteinA protein in the cell membrane that picks up particles and moves them across against the concentration gradient.