- When cells must move materials in an opposite direction - against a concentration gradient.
- Active transport requires Energy.
- Proteins or Pumps are found in the cell membrane transport molecules across the membrane.
Molecular Transport - Proteins are used to move small molecules such as calcium, potassium, and sodium ions across the membrane
- cell takes in large particles by engulfing them
Phagocytosis - "cell eating" - extensions off cytoplasm surround a particle and package it within a food vacuole and then the cell engulfs it. Ex. Amoebas use this process.
Pinocytosis - the process of taking up liquid from the surrounding environment. Tiny pockets form along the membrane, fill with liquid, and pinch off.
- cell gets rid of particles, opposite of endocytosis
- remember the vesicles created by the Golgi Body? These are removed from the cell by exocytosis
The cell removes 3 sodium ions for every 2 potassium ions that enter the cell. This mechanism requires energy.
Think about it.....why does the cell NOT want sodium to build up within its cytoplasm?