What are membrane bound receptors?

BIOLOGY QUESTIONS!!!!?

• 1. Classify each phrase by whether it applies to G protein-coupled receptors only, receptor tyrosine kinases only, both receptors, or neither receptor. -catalyzes the transfer of a phosphate group to the receptor - receptor is located in the plasma membrane -binding of the signaling molecule allows ions to flow through a channel in the receptor -binding site for signaling molecules is located on the extracellular side of the cell -associated with G proteins -binding of the signaling molecule forms a dimer 2. Which of the following statements is false? -The secondary cell wall often contains structural components, like lignin, that form a relatively rigid and complex network within the cell wall. -A plant cell continues growing after the secondary cell wall forms but stops growing with the formation of the tertiary cell wall. -Pectin is a component of the cell wall that attracts and holds water. -When plant cells are growing, they release expansins, which are enzymes that can expand the primary cell wall. 3. Adrenalin is a hormone that binds to a receptor in the plasma membrane. Which statement best explains why adrenalin can stimulate cells in both the heart and liver, yet trigger different responses (increasing heart rate versus releasing glucose)? -The hormone signal is amplified in one tissue but not the other. -Both tissues have adrenalin receptors but the receptors directly activate different target proteins in heart versus liver. -Different molecular forms of adrenalin affect heart versus liver. -Both tissues have adrenalin receptors but signal transduction activates different target proteins in heart versus liver 4. Which of the following would you not find in a plant cell? -polysaccharides -collagen -pectin -lignin 5. Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction? -a signal that binds to a receptor in the cell membrane -a signal that binds to the ECM -a lipid-soluble signal -a signal that is weakly bound to a nucleotide 6. Which statement best explains why the existence of multiple steps in a signal transduction pathway allows it to be regulated by several other pathways? -Multiple steps allow the signal to be amplified. -Multiple steps provide a series of points where hormone can bind. -Multiple steps convert the signal from one form to another. -Multiple steps provide a series of points where cross-talk can occur. 7. What does it mean to say that a signal is transduced? -The signal enters the cell directly and binds to a receptor inside. -The signal triggers a sequence of phosphorylation events inside the cell. -The signal is amplified, such than even a single molecule evokes a large response. -The physical form of the signal changes between the outside of the cell and the inside. 8. Which statement most accurately describes the consequences of loosening the tight junctions between animal epithelial cells? -The flow of molecules from the cytoplasm of one epithelial cell to the cytoplasms of adjacent cells would increase. -Transport of proteins through the plasma membrane of epithelial cells would increase. -The middle lamella would be loosened and the connection between adjacent epithelial cells would be weakened. -Leakage of ions and molecules between the inside and outside of the epithelial layer would become more likely.

• Answer:

  1. G protein-coupled receptors only: associated with G proteins Receptor tyrosine kinases only: binding of the signaling molecule forms a dimer, catalyzes the transfer of a phosphate group to the receptor Both: binding site for signaling molecules is located on the extracellular side of the cell, receptor is located in the plasma membrane Neither: binding of the signaling molecule allows ions to flow through a channel in the receptor 2. A plant cell continues growing after the secondary cell wall forms but stops growing with the formation of the tertiary cell wall. 3. Both tissues have adrenalin receptors but signal transduction activates different target proteins in heart versus liver. 4. Collagen 5. a lipid-soluble signal 6. Multiple steps provide a series of points where cross-talk can occur. 7. The physical form of the signal changes between the outside of the cell and the inside. 8. Leakage of ions and molecules between the inside and outside of the epithelial layer would become more likely.