Guide UPDATED ACTUAL Questions and
CORRECT Answers
receptor activation - CORRECT ANSWER - The "turning on" of a receptor, which often
occurs when a signaling molecule binds to a receptor on a responding cell.
signal transduction - CORRECT ANSWER - The process in which an extracellular
molecule acts as a signal to activate a receptor, which transmits information through the
cytoplasm.
response - CORRECT ANSWER - A change in cellular behavior, such as activation of
enzymes or genes, following a signal.
termination - CORRECT ANSWER - In protein translation, the time at which the addition
of amino acids stops and the completed polypeptide chain is released from the ribosome. In cell
communication, the stopping of a signal.
endocrine signaling - CORRECT ANSWER - Signaling by molecules that travel through
the bloodstream.
paracrine signaling - CORRECT ANSWER - Signaling by a molecule that travels a short
distance to the nearest neighboring cell to bind its receptor and deliver its message.
growth factor - CORRECT ANSWER - Any one of a group of small, soluble molecules,
usually the signal in paracrine signaling, that affect cell growth, cell division, and changes in
gene expression.
autocrine signaling - CORRECT ANSWER - Signaling between different parts of a cell;
the signaling cell and the responding cell are one and the same.
,Neurons have what transmembrane protein? - CORRECT ANSWER - delta
Cells with activated notch transmembrane proteins become? - CORRECT ANSWER -
glial cells
What type of molecule is the delta protein? - CORRECT ANSWER - signaling
Is notch a signaling molecule or receptor? - CORRECT ANSWER - receptor
ligand - CORRECT ANSWER - Alternative term for a signaling molecule that binds with
a receptor, usually a protein.
ligand-binding site - CORRECT ANSWER - The specific location on the receptor protein
where a signaling molecule binds.
G protein-coupled receptor - CORRECT ANSWER - A receptor that couples to G
proteins, which bind to the guanine nucleotides GTP and GDP.
G protein - CORRECT ANSWER - A protein that binds to the guanine nucleotides GTP
and GDP.
receptor kinase - CORRECT ANSWER - A receptor that is an enzyme that adds a
phosphate group to another molecule.
phosphatase - CORRECT ANSWER - An enzyme that removes a phosphate group from
another molecule.
ion channels - CORRECT ANSWER - Cell-surface receptors that open and close, thereby
altering the flow of ions across the plasma membrane.
,What two characteristics do G-protein coupled receptors have? - CORRECT ANSWER -
First, they have a similar structure, consisting of a single polypeptide chain that has seven
transmembrane spanning regions, with the ligand-binding site on the outside of the cell and the
portion that binds to the G protein on the inside of the cell.
Second, when activated, they associate with a G protein.
When a ligand binds to a G protein-coupled receptor, the receptor in turn binds to and activates a
G protein by causing it to release ______ and bind ______? - CORRECT ANSWER -
GDP;GTP
G proteins are active or turned on when bound to ____? G proteins are inactive or turned off
when bound to ____? - CORRECT ANSWER - GTP;GDP
Some G proteins are composed of three subunits, called the? - CORRECT ANSWER -
Alpha, beta, and gamma subunits.
The _____ subunit is the part of the G protein that binds to either GDP or GTP? - CORRECT
ANSWER - alpha
When GDP bound to the α subunit is replaced by GTP, the ____ subunit separates from the
_____ and ____ subunits? - CORRECT ANSWER - Alpha; Beta; Gamma
Is the term "G protein" just a shorter name for a G protein-coupled receptor? - CORRECT
ANSWER - No. A G protein-coupled receptor is a transmembrane receptor that interacts
with a G protein located inside the cell on the cytoplasmic side of the plasma membrane.
denylyl cyclase converts the nucleotide ATP into _____? - CORRECT ANSWER - cyclic
AMP (cAMP)
denylyl cyclase converts the nucleotide ATP into _____? - CORRECT ANSWER - cyclic
AMP (cAMP)
, First messenger - CORRECT ANSWER - First messengers transmit signals from outside
the cell to a receptor.
binding affinity - CORRECT ANSWER - The tightness of the binding between the
receptor and the signaling molecule.
Kit - CORRECT ANSWER - Is a receptor kinase and is important for the production of
pigment in skin, feathers, scales, and hair.
(the name of a protein, like Kit, is capitalized and in roman type. The name of the gene that
encodes the protein, like kit, is lower case and italicized.)
Dimerization - CORRECT ANSWER - partnering of two similar or identical molecules;
activates the cytoplasmic kinase domains of the paired receptors, causing them to phosphorylate
each other at multiple sites on their cytoplasmic tails
Ras - CORRECT ANSWER - is a G protein, but in contrast to the three-subunit G proteins
discussed earlier, Ras consists of a single subunit, similar to the α subunit of the three-subunit G
proteins.
the mitogen-activated protein kinase pathway, or MAP kinase pathway - CORRECT
ANSWER - Activated GTP-bound Ras triggers the activation of a protein kinase that is the
first in a series of kinases that are activated in turn, as each kinase phosphorylates the next in the
series.
PKA is activated by? - CORRECT ANSWER - elevated cAMP levels associated with the
G protein-coupled receptor pathway.
Receptors for polar signaling molecules, including growth factors, are located ? - CORRECT
ANSWER - on the plasma membrane.