Question

1. insulin, a hydrophilic compound, binds to a (click to select) site on the cells extracellular surface, causing activation of a second messenger system on the cells interior.
2. a substrate binds to a receptor site forming the (click to select) complex and releases products following catalysis of the chemical reaction.
3. a (click to select) channel allows a constant flow of sodium through the plasma membrane down its own electrochemical gradient.
4. a (click to select) channel allows for discriminatory permeability of solutes only at designated times.
5. circulating plasma antibodies recognize a (click to select) as \self\ and thus do not initiate an immune response.
6. integrins bind materials or cells in the (click to select) matrix and use them to move through space.

Explanation:

1. Insulin binds to a receptor site on the cell's extracellular surface to activate a second - messenger system.
2. A substrate - enzyme complex is formed when a substrate binds to an enzyme's receptor site.
3. A leak channel allows a constant flow of ions like sodium down its electrochemical gradient.
4. A gated channel allows for discriminatory permeability at specific times.
5. Circulating plasma antibodies recognize self - antigens and do not initiate an immune response.
6. Integrins bind to materials or cells in the extracellular matrix for movement.

Answer:

1. Receptor
2. Enzyme - substrate
3. Leak
4. Gated
5. Antigen
6. Extracellular