Exam 9: Cell Communication

What characteristics do all cell surface receptors share?

___________ among cells is a hallmark of multicellular organisms.

Located on or within the cell are _________ proteins,each of which has a three dimensional shape complementary to that of a specific signal molecule.

A small number of surface receptors can ultimately generate a large intracellular response,as each step of the pathway is often expanded by signal _________.

Most cells are in physical contact with other cells at all times by forming permanent connections called

The class of cell surface receptors that acts indirectly on plasma membrane-bound enzymes or ion channels is called

The space into which neurotransmitters are released is called a chemical

Your research project involves the characterization of a particular signal transduction pathway.Specifically,you have been studying a receptor tyrosine kinase and protein X,which initiates downstream events.You are certain that protein X is part of the signal transduction pathway,but have been unable to identify a direct protein-protein interaction between the receptor tyrosine kinase and the protein X.What should you do next?

A researcher is trying to produce a new cancer drug to be tested on small tumors.The tumor has to be localized in a small area of the body and cannot have metastasized (spread to other areas of the body).Furthermore,this drug must prohibit the signaling from one tumor cell to another tumor cell.Given the above information,this new drug will prohibit

You are having lunch with an elderly friend when suddenly he begins to experience chest pain and tightness.He reaches into his pocket,gets out one of his nitroglycerin tablets and quickly takes it.After the episode passes,your friend asks you how the nitroglycerin helps his angina.You explain that nitroglycerin gets converted by cells to NO causing the smooth muscle cells of the blood vessel to relax and increase blood flow to the heart.He pushes you for a more detailed explanation,so you explain further that

Adjacent cells can signal others by direct contact,while nearby cells that are not touching can communicate by the release of __________ signals.

You are performing an experiment to assay phosphorylation of a substrate by a protein kinase.Based on the data in the table below,what do these experimental results suggest?

You are studying the effect of a secreted signal molecule on the activity of a cytoplasmic enzyme.Prior studies have shown the signal molecule is required for enzyme activity.You add the signal molecule to a test tube solution containing both the enzyme and its substrate.After incubating the solution,you assay for the reaction product as a measure of enzyme activity,however,no product was detected.By comparison,when you add the signal molecule to a vial containing intact cells,you are able to detect the reaction product.Which of the following statements is inconsistent with these experimental results?

Which of following statements about G proteins associated with G-protein-coupled receptors is false?

A team of researchers at a pesticide company are working produce a new rodent poison to address a growing problem of rat infestations at an old waterfront warehouse.The researchers are developing a poison that will cause the junctions between intestinal cells to break down.The poison will be incorporated into grain and left where the rodents will feed on it.Which of the following describes the most likely effect of this poison?

Protein kinases,enzymes which add phosphate groups to proteins,are an example of ______________ receptors.

Vasopressin is a hormone that is primarily released when the body is low on water.Release of vasopressin causes the kidneys to conserve water by concentrating urine and decreasing urine output.However,vasopressin also has additional functions in other tissues such as the brain and blood vessels,which are not directly involved in urine production.How could it be possible for vasopressin to trigger different responses in different tissues?