Part Multiple Choice: ½ point each, 17 points total 1: Chapter 14: ) Which of th
ID: 210700 • Letter: P
Question
Part Multiple Choice: ½ point each, 17 points total 1: Chapter 14: ) Which of the following statements concerning the properties receptor systems is correct? A) Steroids are produced from cholesterol. of ligands for intracellular B) Changes in the composition of your diet can affect the concentration of some of these in your body C) Some ligands are bound to specific proteins when crried in the blood D) both choices A and C E) choices A, B, and C 2 With regard to hormones, A) paracrine. B) endocrine. responses occurring over the shortest distance would be classified as over the D) juxtacrine. E) All of the above choices work over similar distances. 3) Kinases and phosphatases are essential in the cell because they A) help turn proteins "on and off through changes in phosphorylation status B) are enzymes that destroy damaged proteins. C) sense short poly-A tails in mRNA as a signal to degrade the mRNA. D) destroy second messengers, thereby turning off a signal transduction pathway E) all of the above 4) You have recently identified a molecule that you believe to be a ligand associated with a signal transduction mechanism. All you know about this ligand is that chemically it is hydrophilic. As a result, you expect it to interact with its receptor A) at the outer cell surface. B) within the cytoplasm of the cell. C) within the nucleus of the cell. D) on the cytoplasmic side of the plasma membrane. CopynExplanation / Answer
1. choices A,B and C
Ligands of intracellular receptors are small, hydrophobic molecules, since they must be able to cross the plasma membrane in order to reach their receptors. Cholesterol is the natural precursor for all steroids hormones which acts as ligands. Changes in the composition of your diet can affect the concentration of some of these ligands. Some ligands are bound to specific proteins when carried in blood.
2. Paracrine
Often, cells that are near one another communicate through the release of chemical messengers. This type of signaling, in which cells communicate over relatively short distances, is known as paracrine signaling.
3. help turn proteins on and off through changes in phosphorylation status
A kinase is a type of phosphotransferase that transfers a phosphate group from ATP to a substrate. A phosphatase is a type of hydrolase that removes a phosphate group from the substrate.
4. at the outer cell surface
Hydrophilic signaling molecules, or ligands, act by binding to receptor proteins on the surface of target cells since they are unable to cross the plasma membrane of their target cells.