Which of the following would be a proper expression for the dissociation constant associated with ligand
(L) binding to receptor (R)?
Kd=[R][L]/[R*L]
The most notable difference between _____ and other lipids is the presence of four fused rings.
cholesterol
Which of the following residues would you expect in the membrane spanning portion of an integral
membrane protein?
Leu and Ile
The bonding of alcohols to the anomeric center of a carbohydrate results in the formation of a(n)
__________ bond.
glycosidic
Cellulose is
a linear polymer of glucose with ?(1?4) linkages
How is an enzyme-catalyzed reaction affected by the addition of more enzyme?
velocity will increase
Which of the following can be a hormone?
all of the above:
A) amino acid derivatives
B) steroids
C)polypeptides
D) eicosanoids
The affinity of enzyme binding to its substrate is approximated by the ________ value
KM
A pore that simultaneously transports two different molecules in the same direction is called a(n)
symporter
Membrane fluidity is influenced by
all of the above:
A) van der Waals contacts
B) acyl chain length
C) degree of acyl chain saturation
D) cholesterol concentration within the membrane
Which amino acid in the aquaporin channel hydrogen bonds with water to prevent the movement of
protons?
Asn
Unlike proteins and oligonucleotides, polysaccharides
often have branched structures
A molecule moves across a membrane from a lower to a higher concentration with the aid of a membrane
protein. This process is known as:
active transport
The catalytic constant, or kcat, is also known as the
turnover number
The initial velocity (v0) of an enzyme-catalyzed reaction
is dependent upon the substrate concentration
A ligand that binds to a receptor to elicit a biological effect is known as a(n)
agonist
Which of the following is not an example of a passive-mediated transporter?
Na+/K+ transporter
Which of the following statements about the Na+/K+ transporter is (are) TRUE?
Phosphate hydrolysis of the transporter releases K+ ions to the cytosol and results in a return to the
original (resting) state of the transporter.
Glycosphingolipids with complex carbohydrate head groups that often serve as cellular receptors are
gangliosides
The movement of glucose into a cell when blood sugar is high is accomplished by _____. The movement
of K+ against its concentration gradient is accomplished by _____.
passive transport; active transport
What is the initial velocity of a reaction when Vmax = 3.6 x 10-3 mol/s, KM = 4.5 mM, and [S] = 1.5 mM?
0.9 mmol/s
How does cAMP influence glycogen breakdown?
cAMP activates protein kinase A, which phosphorylates the enzyme phosphorylase kinase, which
then activates glycogen phosphorylase to break down glycogen.
All known porins are _____ proteins composed of ____
trimeric; ?-barrels
Which of the following would be positively charged at physiological pH?
glucosamine
A typical ? barrel transmembrane protein contains ____ ? strands.
8-22
Which of these characteristics is not found in naturally occurring fatty acids in mammals?
they are found free and unassociated with other molecules
Which of the following is a ligand of the ?2-adrenergic receptor?
norepinephrine
Amylopectin contains primarily _____ glycosidic bonds with _____ glycosidic bonds as branch points
?(1?4); ?(1?6)
Which of the following expresses the velocity for an enzyme-catalyzed reaction that obeys Michaelis-Menten
kinetics?
v = k2[ES]
Activity of the Ras protein is analogous to the _____ in terms of its ability to bind GTP
G protein ? subunit
If the rate constant for the reaction: A + B ? C is 0.25 mM-1�s-1 when [A] = [B], what is the substrate
concentration under these conditions when v0 = 16 mM/s?
8 mM
What percentage of Vmax is obtained when the substrate is present at 1/4 of the KM?
20%
Which of the following are characteristic of cellulose?
all of the above:
A) highly extended fibers
B) ?(1?4) glycosidic bonds
C) extensive hydrogen bonding between individual molecules
D) unbranched polymer
What factor(s) are important in the high selectivity of the K+ channel?
A network of Tyr residues ensures that smaller ions like Na+ will be excluded.
What limits the signaling activity of a G protein once it has been stimulated by an epinephrine binding
receptor?
GTPase activity of the alpha subunit
In an ?-helical protein that spans a cell membrane, _____ would likely be in the center of the membrane
while _____ would likely be associated with the polar head groups and _____ would likely be associated
with the aqueous environment
Leu; Gln; Asp
Which of the following types of inhibition can be reversed by addition of more substrate?
competitive inhibition
The concentration of cytosolic Ca2+ is _____ the extracellular concentration
less than
Which of the following would be the first to occur following opening of Ca2+ channels during
acetylcholine-mediated neurotransmission to a muscle cell?
binding of SNARE complex to synaptic vesicles and pre-synaptic membrane
Which of the following would be likely to form a bilayer in a solution containing only the lipid indicated?
glycerophospholipids
PEP regulation of phosphofructokinase activity is a type of
allosteric regulation
Insulin _____ glycogen synthesis and _____ nutrient mobilization.
activates; inhibits
In the simple enzyme-catalyzed reaction below, which of the rate constants would be first order?
E + S <-k(-1)---k1-> ES ---k2-> E + P
[k(-1) is ES going to E+S and k1 is E+S going to ES]
k(-1) and k2
Plants can synthesize trienoic acids (fatty acids with 3 double bonds) by introducing another double bond
into a dienoic acid. Would you expect plants growing at higher temperatures to convert more or less of
their dienoic acids into trienoic acids?
they would convert less
Desensitization of a G protein-coupled receptor is caused by phosphorylation of the receptor by a
specific kinase. What protein recognizes the phosphorylated receptor?
arrestin
A toxin secreted by the bacterium Vibrio cholerae catalyzes the covalent attachment of an ADP-ribose
group to the ? subunit of the G protein. This results in the inhibition of the intrinsic GTPase activity of
the G protein. How does this affect the activi
Lasting activation of adenylate cyclase leads to high [cAMP]
Aspartate transcarbamylase (ATCase) catalyzes the formation of N-carbamoylasparate from carbamoyl
phosphate and aspartate as the first step of the multli-step synthesis of CTP:
carbamoyl phosphate + aspartate --> N-carbamoylaspartate --> --> --> UMP --> -
a) The KM decreases in the presence of ATP and increases the affinity of the substrate
b) inhibitor
c) 6.5
A membrane consisting only of phospholipids undergoes a sharp transition from the crystalline form to
the fluid form as it is heated. What would be the effect on this transition in a membrane containing 80%
phospholipid and 20% cholesterol?
The shift from the crystalline to the fluid form would be more gradual.