Active Transport

  • Active transport is a process that enables cells to move molecules from an area of low concentration to an area of high concentration. This is against the concentration gradient - the natural movement of molecules from high to low concentration.

  • It’s labelled “active” because it requires energy from the cell in the form of ATP (adenosine triphosphate). ATP is produced by the cell through the process of respiration.

  • Protein carriers within cell membranes play a crucial role in active transport. They bind with specific molecules on one side of the membrane, change shape using ATP energy, and release the molecules on the other side.

  • Active transport is important for many biological processes. For instance, in the human body, it allows nutrients from the diet to be absorbed by the gut, even when the concentration of nutrients inside the gut cells is higher than in the gut.

  • The sodium-potassium pump in neurones is a prime example of active transport. This pump moves potassium ions into the cell and sodium ions out of the cell against their concentration gradients, allowing nerve impulses to be transmitted.

  • Another example of active transport is the accumulation of ions in root hair cells of plants. This causes water to move into the cells by osmosis, aiding in absorption of water and nutrients from the soil.

  • Active transport can also remove waste products from cells even when the concentration of waste is higher outside of the cell.

  • Active transport enables cells to maintain an optimal internal environment, or homeostasis, despite changes in the external environment.

  • A level of control is exerted over active transport to prevent the wasteful use of energy. This regulation is usually based on the needs of the cell and the availability of ATP.

  • Significant in biological processes, any disruption to active transport can lead to cell dysfunction and disease. The cystic fibrosis disease is a classic example where a mutation impairs the active transport of chloride ions, leading to a build-up of mucus in the lungs.

Remember, active transport is key to cells being able to move substances to where they are needed, even if it is against a concentration gradient, making it fundamental for maintaining life processes at the cellular level.