Active Transport and Energy Use in Cells
This page delves into the concept of active transport, its importance in cellular processes, and how it differs from passive transport mechanisms like diffusion and osmosis.
What is active transport?
Active transport is a crucial cellular process that moves molecules across a membrane against their concentration gradient, requiring energy from the cell.
Definition: Active transport process and cellular energy use refers to the movement of molecules across a cellular membrane from an area of low concentration to an area of high concentration, using cellular energy.
Key features of active transport
• Requires energy, typically from cellular respiration
• Moves substances in and out of cells
• Essential for the digestive system
• Operates against concentration gradients
Example: In humans, active transport allows sugar molecules to be absorbed from the small intestine when the sugar concentration is higher in the blood than in the small intestine.
Active transport in different organisms
Active transport is not limited to human cells. In plants, it plays a crucial role in nutrient absorption:
Example: In plants, active transport is used to absorb mineral ions into root hair cells from more dilute solutions in the soil.
Concentration gradient and diffusion rate
The page also revisits the concept of concentration gradients and their impact on diffusion:
• The larger the concentration gradient, the faster the rate of diffusion
• Higher temperatures increase the rate of diffusion
Highlight: The concentration gradient and temperature are key factors affecting the rate of diffusion in biological systems.
Visualizing diffusion
The page includes a diagram illustrating the process of diffusion, using the example of perfume molecules dispersing in air.
Vocabulary: Concentration gradient - The difference in concentration of a substance between two areas, which drives the direction of diffusion.
