From the perspective of the cell receiving the message, the three stages of cell signaling are:

signal reception, signal transduction, and cellular response

The process of transduction usually begin

when the signal molecule changes the receptor protein in some way

The signal transduction pathway in animal cells that uses epinephrine

activates the breakdown of glycogen in liver and skeletal muscles

A small molecule that specifically binds to another molecule, usually a larger one

is called a ligand

Which is (are) true of ligand-gated ion channels?

A. they are important in the nervous system

B.they lead to changes in sodium and calcium concentrations in the cell

C. they open or close in response to a chemical signal

a receptor protein in a membrane that recognizes a chemical signal is most similar to

the active site of an enzyme in the cytoplasm that binds to a specific substrate

Most signaling molecules

A. bind to specific sites on receptor proteins in a membrane

B. are water-soluble

what would be TRUE for the signaling system in an animal cell that lacks the ability to produce GTP

It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane

Membrane receptors that attach phosphates to specific amino acids in proteins are

called receptor tyrosine-kinases

Which are chemical messengers that pass through the plasma membrane of the cells and have receptor molecules in the cytoplasm

B. nitric acid

C. testosterone

Testosterone functions inside a cell by

binding with a receptor protein that enters the nucleus and activates specific genes

The receptors for a group of signaling molecules known as growth factors are often

receptor tyrosine kinases

In general, a signal transmitted via phosphorylation of a series of proteins

brings a conformational change to each Protein

Which is (are) TRUE regarding the activity of a protein regulated by phosphorylation

It depends on the balance in the cell between active kinase and active phosphatase molecules

Which is (are) widely used and second messenger in signal transduction pathways

A. calcium ions

B. cyclic AMP

C. inositol triphosphate

An animal deficient in adenylyl cyclase

would not respond properly to epinephrine

the general name for an enzyme that transfers phosphate groups from ATP to a protein is

protein kinase

the toxin of Vibrio Cholerae causes profuse diarrhea because it

modifies a G protein involved in regulating salt and water secretion

In a typical cell, calcium ions are

A. far more abundant in the blood and other extracellular fluid than in the cytoplasm

B. rapidly released from the endoplasmic reticulum in response to G-protein mediated signals

C. often concentrated within the endoplasmic reticulum

Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins

receptor tyrosine kinase activity

Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed

cAMP

An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum

phospholipase C

A drug designed to inhibit the response of cells to testosterone would almost certainly result in which of the following

a decrease in transcriptional activity of certain genes

The response of a particular cell to a signal depends on

A. its particular collection of signal receptor proteins

B. its relay proteins

C. the proteins needed to carry out the response

Which example below is a protein that can hold several other relay proteins as it binds to an activated membrane receptor

scaffolding protein