Quiz 3 Flashcards
One way that cells can increase their responsiveness to a signaling molecule is by
increasing the number of their transmebrane receptors by fusion of intracellular vesicles with the cell membrane.
Cocaine lowers the levels of a chemical messenger in the brain called enkephalin. Researchers have found the number of enkephalin receptors to be higher in cocaine addicts than in nonaddicted persons. This is an example of
up-regulation.
In which situation would an injected drug be the most effective agonist for an endogenous signal molecule?
The drug achieves 50% saturation of the signal molecule’s receptors at a lower concentration than that of the endogenous signal molecule.
What is the role of Ca+2 in the second-messenger cascade involving phospholipase C, diacylglycerol and inositol trisphosphate?
Along with Diacylglycerol, it activates Protein Kinase C.
Which of the following is NOT TRUE of cAMP?
It is found on the outside of the cell membrane.
Second messengers do not include __________.
adenylyl cyclase
Which of the following reflects the fact that a receptor normally binds only to a single signaling molecule?
specificity
In the phospholipase C mechanism of signal transduction, most of the increase in intracellular calcium comes from _________.
the endoplasmic reticulum
Which of the following is an example of a trimeric protein associated with a receptor?
G protein
Which of the following is an example of a first messenger?
neurotransmitter or hormone
When epinephrine binds to alpha adrenergic receptors on smooth muscle in intestinal blood vessels, the blood vessels [1]; however, when epinephrine binds to beta adrenergic receptors on certain skeletal muscle blood vessels, the blood vessels [2].
1) vasoconstrict
2) vasodilate
The term for the desired target value for a parameter is
setpoint
Which of the following is an example of an enzyme involved in signal transduction?
cAMP-dependent protein kinase (protein kinase A)
The term that matches “continuously monitors its environment for a specific variable”
sensory receptor
Insulin is a protein hormone with mostly hydrophilic amino acids. Which is the most likely description of its receptor?
Integral membrane protein.
Both insulin and glucagon are peptide hormones that target liver cells. The response of the target cells to each of these two hormones is opposite. This information implies that _________.
Both “the two hormones bind to different cell surface receptors” and “each of the hormones uses a different second messenger.”
The enzyme that catalyzes the production of cAMP from ATP is phosphodiesterase.
False
An antagonist blocks the action of a chemical messenger by binding to its receptor.
True
Type 2 Diabetes mellitus is a disease in which the effect insulin has on cells is diminished, despite normal levels of insulin (at the beginning of the disease). Which of the following could possibly explain this phenomenon? Select all answers that apply.
Down-regulation of insulin receptors.
Decreased expression of the second messenger in the insulin pathway.
Match the communication signal with its property.
neurohormone =
neurotransmitter =
neurohormone = chemical
neurotransmitter = chemical
