| Location | Transporter | Molecules moved | | :--- | :--- | :--- | | Animal cell membrane | Na⁺/K⁺ ATPase | Na⁺ (out), K⁺ (in) | | Mitochondria | H⁺ ATP synthase (reverse) | H⁺ (across inner membrane) | | Plant cell membrane | H⁺ ATPase | H⁺ (out of cell) | | Stomach parietal cells | H⁺/K⁺ ATPase (proton pump) | H⁺ (out), K⁺ (in) | | Intestinal epithelium | SGLT1 (symporter) | Na⁺ (in) & glucose (in) |
Because this movement opposes the natural flow of diffusion (where particles move from high to low concentration), the cell must expend energy—usually in the form of a molecule called Adenosine Triphosphate (ATP)—to make it happen. what is active transport in a cell
| Feature | | Passive Transport (Diffusion) | Facilitated Diffusion | | :--- | :--- | :--- | :--- | | Gradient | Against | Down | Down | | Energy required | Yes (ATP or indirect) | No | No | | Protein needed | Yes (carrier/pump) | No (for simple) | Yes (channel/carrier) | | Example | Na⁺/K⁺ pump | O₂, CO₂ movement | Glucose into RBCs | | Location | Transporter | Molecules moved |
Active transport is the cell's way of maintaining —a stable internal environment. By spending energy to move substances exactly where they are needed, the cell ensures it has the nutrients to grow and the electrical charge to communicate, regardless of what is happening in the world outside the membrane. Passive Transport: The Key Difference is the biological
Because this movement goes against the "concentration gradient" (the natural tendency of particles to spread out), it does not happen spontaneously. To make it work, the cell must expend energy, usually in the form of . Active vs. Passive Transport: The Key Difference
is the biological process by which cells move molecules across their membrane from an area of lower concentration to an area of higher concentration. In simpler terms, it is moving substances "uphill" or against the gradient.
is the movement of molecules or ions across a cell membrane against their concentration gradient (from an area of lower concentration to an area of higher concentration). This process requires energy (usually in the form of ATP) and the involvement of specific membrane transport proteins (carrier proteins).