Key Concepts: Active Transport

Active transport is an essential biological process which moves substances against their concentration gradient. This means it transports molecules from an area of lower concentration to one of higher concentration.
Being an ‘active’ process suggests energy is required for it to happen. This energy is delivered in the form of ATP (adenosine triphosphate).
Active transport often involves the use of carrier proteins. These are proteins in the cell membrane which help transport specific substance across the cell boundary.
The process starts with the substance attaching itself to the carrier molecule on the outer surface of the cell.
Energy from ATP is used to change the shape of the carrier protein. This alters the shape in a way that makes the substance be pushed across the membrane to the other side.
Active transport is crucial in maintaining cell homeostasis. Cells rely on it to uptake necessary nutrients even when the concentration gradient is not in favour.
One example of active transport is the uptake of glucose in the human gut. Even when the concentration of glucose in gut cells is higher than in the gut, glucose is still absorbed into the gut cells by active transport.
Another example is the uptake of ions from soil by plant roots. Plants absorb minerals such as potassium and nitrates from the soil through active transport.
Active transport can also help cells get rid of waste or dangerous substances by pumping them out.
Remember, diffusion and osmosis (both passive transport processes) set in motion when a concentration gradient exists, requiring no energy. But active transport allows cells to act against the concentration gradients, and hence requires energy.
It’s crucial to understand the importance of active transport in the human body, plant life, and overall cellular function. As it allows cells to maintain conditions that are optimal for their functioning, even when these conditions go against the natural process of diffusion.