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