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In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan. 2022 Sep 12. Affiliations
Free Books & Documents Book Physiology, Active TransportIsaac Chen et al. Free Books & Documents ExcerptThere are two main modes of transport of molecules across any biological membrane. These are passive and active transport. Passive transport, most commonly by diffusion, occurs along a concentration gradient from high to low concentration. No energy is necessary for this mode of transport. Examples will include diffusion of gases across alveolar membranes and diffusion of neurotransmitters such as acetylcholine across the synapse or neuromuscular junction. Osmosis is a form of passive transport when water molecules move from low solute concentration(high water concentration) to high solute or low water concentration across a membrane that is not permeable to the solute. There is a form of passive transport called facilitated diffusion. It occurs when molecules such as glucose or amino acids move from high concentration to low concentration facilitated by carrier proteins or pores in the membrane. Active transport requires energy for the process by transporting molecules against a concentration or electrochemical gradient. Active transport is an energy-driven process where membrane proteins transport molecules across cells, mainly classified as either primary or secondary, based on how energy is coupled to fuel these mechanisms. The former constitutes means by which a chemical reaction, e.g., ATP hydrolysis, powers the direct transport of molecules to establish specific concentration gradients, as seen with sodium/potassium-ATPase and hydrogen-ATPase pumps. The latter employs those established gradients to transport other molecules. These gradients support the roles of other membrane proteins and other workings of the cell and are crucial to the maintenance of cellular and bodily homeostasis. As such, the importance of active transport is apparent when considering the various defects throughout the body that can manifest in a wide variety of diseases, including cystic fibrosis and cholera, all because of an impairment in some aspect of active transport. Copyright © 2022, StatPearls Publishing LLC. Sections
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Which of these processes requires cells to expend energy in the form of ATP?In active transport, unlike passive transport, the cell expends energy (for example, in the form of ATP) to move a substance against its concentration gradient.
What requires the cell to expend energy?In active transport mechanisms, the cell must expend energy to move molecules into or out of the cell. For potassium, cells have special proteins that form a sodium-potassium pump.
Does the cell expend ATP for osmosis to occur?Answer and Explanation: In the case of osmosis, the cell does not need to use cell energy. ATP is the form of energy that is meant by the term "cell energy", and no ATP would be required for osmosis.
Which type of cell transport requires the expenditure of ATP?Primary active transport is also called direct active transport or uniport. It involves using energy (usually ATP) to directly pump a solute across a membrane against its electrochemical gradient.
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