THE CELL
CELL COMMUNICATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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small, nonpolar, hydrophobic
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large, polar, hydrophilic
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small, polar, hydrophilic
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large, nonpolar, hydrophobic
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Detailed explanation-1: -Water-soluble ligands are polar or charged and cannot readily cross the plasma membrane. So, most water-soluble ligands bind to the extracellular domains of cell-surface receptors, staying on the outer surface of the cell.
Detailed explanation-2: -Signaling molecules can range from small proteins to small ions and can be hydrophobic, water-soluble, or even a gas. Hydrophobic signaling molecules ( ligands ) can diffuse through the plasma membrane and bind to internal receptors.
Detailed explanation-3: -Receptor proteins are located in the cell’s plasma membrane and, in some cases, within the cytoplasm of the cell. However, receptor proteins and their associated signal pathways not necessarily are evenly distributed over the surface of the cell.
Detailed explanation-4: -Facilitated diffusion therefore allows polar and charged molecules, such as carbohydrates, amino acids, nucleosides, and ions, to cross the plasma membrane.
Detailed explanation-5: -2. Transduction: When the signaling molecule binds the receptor it changes the receptor protein in some way. This change initiates the process of transduction. Signal transduction is usually a pathway of several steps.