Proteins & Active Transport | Biology for GCSE/IGCSE - Year 11 PDF Download

Importance of Active Transport

• Energy is crucial in active transport since it facilitates the movement of particles against their natural concentration gradient, opposing the direction of diffusion.
• Active transport plays a pivotal role in transporting molecules or ions across membranes, enabling essential biological processes.
• Examples of active transport include the absorption of glucose by epithelial cells in the villi of the small intestine and kidney tubules in the nephron, as well as the uptake of ions from soil water by root hair cells in plants.

Protein Carriers

Active transport mechanisms rely on carrier proteins embedded within the cell membrane to facilitate the movement of specific molecules against their concentration gradient:

• Initially, the substance binds with a carrier protein molecule located in the cell membrane.
• The carrier protein undergoes a shape change, powered by the energy derived from cellular respiration, enabling it to transport the substance across the membrane.
• Subsequently, the substance is released into the cell, completing the transport process.