Movement of chemicals within a cell occurs in accordance with concentration gradients.
Process can involve moving substances from an area of low concentration to an area of high concentration.
This process is termed active transport, as it necessitates cellular energy (ATP) to proceed against the natural flow of particles, usually from high to low concentration.
Definition of Active Transport
Active Transport: A cellular process that utilizes energy to move substances across a membrane against their concentration gradient.
Movement occurs from the side where concentration is lower (low concentration) to the side where concentration is higher (high concentration).
Active transport requires effort and energy, specifically in the form of ATP (adenosine triphosphate).
Mechanism of Active Transport
In active transport, specific protein channels called pumps facilitate the movement of chemicals across the cell membrane.
Pumps: Specialized protein structures embedded in the cell membrane that aid in moving substances from low to high concentration.
Example: An active transport pump may move sodium ions (Na+) from inside the cell, where there is a higher concentration, to the outside, where there is lower concentration, using ATP as the energy source.
Types of Active Transport Processes
Active transport can involve various forms, including:
Endocytosis: The process through which a cell engulfs material from the outside environment by engulfing it with its membrane, forming a bubble (vesicle).
Types of endocytosis include:
Pinocytosis: A form of endocytosis where the cell takes in extracellular fluid (liquid) by forming small vesicles.
Phagocytosis: A type of endocytosis in which solid particles (e.g., food, pathogens) are engulfed by the cell and transported within a vesicle.
Exocytosis: The process whereby a cell expels material to the outside via vesicles formed from the membrane.
The prefix 'exo' means "outside," indicating that this process is centered on moving substances out of the cell.