Download Name: Cell Biology Unit Test #1

Name:_________Practice Test__________________ Cell Biology Unit Test #1: 50 points
Useful Formulas:
Keq= [products]/[reactants]
MM kinetics: v= Vmax [S]/(Km+[S])
LB Kinetics: 1/v= (Km/Vm)(1/[S]) + 1/Vmax
∆G= ∆G’o + 2.303 RT log [products]/[reactants]
Remember that 2.302(log X) = ln X
o
∆G’ = 2.303 RT log Keq
R=1.987 cal/mol K T=298 K Kelvin = oC + 273
Multiple Choice: Choose the single best answer for each of the following (1 pt each)
Please double check your scantron for smears and incomplete bubble marks.
1) Which amino acid is often phosphorylated by kinases in cell signaling pathways?
A) Glutamate B) Arginine C) Serine D) Glycine E) Proline
2) Which amino acid contains sulfur?
A) Lysine B) Methionine C) Valine
D) Glutamate E) Threonine
3) True/False: Eukaryotic cells are in most cases larger than prokaryotic cells. A) True
B) False
4) Gases exchange (oxygen and carbon dioxide) would be most efficient in which cell?
A) 4X50X50 um cell
B) 10X50X50 um cell
5) If a red blood cell was put into 500 mM NaCl what would be most likely to occur?
A) Crenation B) Isotonicity C) Lysis D) Homeostasis
6) In a typical human cell at rest, the Na+/K+-ATPase maintains the extracellular concentration of sodium at
approximately _____mM and the intracellular concentration at about _______mM.
A) 14, 1.0 B) 140, 10 C) 10, 140 D) 4.0, 100
7) A typical human cell is approximately ________in size.
A) 1X2X2nanometers B)10X20X20micrometers C)100X200X200micrometers D) 1X2X2 millimeters
8) Which of the following is NOT surrounded by a lipid bilayer and both contains RNA and protein?
a) Nucleus b) Mitochondria c) Peroxisome d) Ribosome e) Golgi apparatus
9) Secretory vesicles are generated by what organelle?
a) Nucleus b) Mitochondria c) Peroxisome d) Ribosome e) Golgi apparatus
10) What organelle has the greatest ability to produce ATP in the presence of oxygen?
a) Nucleus b) Mitochondria c) Peroxisome d) Ribosome e) Golgi apparatus
11) The four subunits of hemoglobin make up what level of protein structure?
a) Primary b) Secondary c) Tertiary d) Quaternary
12) If every carbon in a molecule had a hydrogen and an alcohol group attached, and one carbon had an aldehyde, the
molecule would probably be what?
a) Carbohydrate b) Protein c) Fatty acid
d) Nucleotide
13) In the human liver, excess cellular glucose can be stored in a polysaccharide called______.
a) Fatty acid b) Protein c) Glycogen d) Disaccharide e) Starch
14) A ______is the most distinctive part of a monounsaturated fatty acid.
a) Carboxyl b) Ketone c) Carbon-carbon double bond d) Amine
e) Glycerol backbone
15) Which molecule would be most amphipathic?
A) Cholesterol B) Triglyceride C) The amino acid serine D) Membrane phospholipid
16) A form of cellular energy that becomes light would be what?.
a) Biosynthesis b) Homeothermy c) Concentration gradients
d) Flagella
e) Bioluminescence
17) A typical cell may use up to how much energy to maintain the concentration gradients for Na+, and K+?
A) 25% b) 33% c) 75%
d) 99%
18) If an organ oxidized two grams of glucose to carbon dioxide, how many Calories of energy could be generated?
A) 2 B) 4 C) 8 D) 4,000 e) 18,000
19) Ultimately we as humans are all ______ organisms.
a) Autotrophic b) Heterotrophic c) Allosteric
d) Autocatalytic
20) True/False: Standard Free Energy (∆G’o) for a chemical reaction is determined by putting the reactant(s) and
product(s) into solution at 1 M concentrations and evaluating the equilibrium constant (assume 25 C).
a) True b) False
21) The equilibrium constant (Keq) for this reaction is what? At equilibrium the react and product concentrations were:
A) Keq= 0.25/1.75= 0.14
B) Keq= 1.75/0.25= 7
C) Cannot determine Keq based in information provided
22) Which of the following could cause a reaction with a positive ∆G’o to become more favorable with respect to
making product.
A) Remove product when produced
B) Increase the substrate concentration
C) Alter the temperature of the reaction D) All of the above
23) True/False: A chemical reaction in the cytosol that has a large Positive value (+6.5) for its Delta G could run if
ATP is hydrolyzed to ADP and Pi at the same time. A) True B) False
24) True/False: Enzymes lower the activation energy by stabilizing the transition state of reactions.
a) True b) False
25) True/False: Enzymes make the Standard Free Energy for a specific reaction more negative.
a) True b) False
26) True/ False: If one chemical reaction with a ∆G’o = - 10 occurs in the cytosol and another reaction with a ∆G’o of
+3.3 occurs inside a mitochondria, the two ∆G’o values can be added and the net ∆G’o will be negative.
a) True b) False
27) True/False: The Michealis-Menten constant (Km) of an enzymatic reaction is the substrate concentration required
to achieve half of the maximal reaction velocity. A) True B) False
28) Enzyme function is often regulated by the local environment. For example the four globin subunits of hemoglobin
will tend to bind oxygen less tightly (dump oxygen) when what environment or event occurs?
a) Warm temperatures are encountered
b) Acidic environments are encountered
c) Hypoxic environments are encountered
d) Carbon dioxide is generated in an active muscle
e) All of above
29) When enzyme activity is measured, which type of plot permits the investigator to only estimate Vmax?
a) Lineweaver-Burk b) Michealis-Menten
30) What type of enzyme would permit Glucose-6-phosphate to rearrange its shape to become Fructose-6-phosphate?
A) Hydrolase
B) Isomerase C) Phosphatase D) Oxido-reductase
31) What kind of enzyme would add a phosphate to a target molecule?
A) Phosphatase B) Isomerase C) Nuclease D) Kinase
32) Trypsinogen from the pancreas is able to digest proteins in the intestine when an inhibitory peptide fragment is
removed by the intestinal enzyme enterokinase. What regulatory method is this?
A) pH Regulatory Signal
B) Modified Enzyme Production C) Proteolytic Cleavage
D) Allosteric Modification
E) Autocatalytic Cleavage
33) One of the initial products of glycolysis (Fructose-1,6-bisphospahte) binds to a regulator site on pyruvate kinase at
the end of the glycolytic pathway, causing glycolysis to progress more rapidly. What type of regulation is this?
A) pH Regulatory Signal
B) Modified Enzyme Production C) Proteolytic Cleavage
D) Allosteric Modification
E) Autocatalytic Cleavage
34) True/False: The binding of a substrate to the specific active site of an enzyme induces a change in the protein
shape, this is a term called “induced fit”.
A) True B) False
35) T/F: Allosteric regulation occurs when a molecule binds at the active site of an enzyme resulting in a change in
enzyme shape and function.
A) True B) False
Write these answers in the spaces provide below:
Useful Formulas: Consider reaction A + B  C + D Keq= [products]/[reactants]
MM kinetics: v= Vmax [S]/(Km+[S])
LB Kinetics: 1/v= (Km/Vm)(1/[S]) + 1/Vmax
o
∆G’= ∆G’ + 2.303 RT log [products][products/[reactants][reactants]
Remember that 2.302(log X) = ln X
∆G’o= -2.303 RT log [C][D]/[A][B]
R=1.987 cal/mol K T=298 K Kelvin = oC + 273
36) Consider this reaction in a skeletal muscle cell at the start of exercise: (3 pts each)
Phosphocreatine= 20 mM, Creatine = 8 mM, ADP=1 mM, ATP=7 mM, PO4= 5 mM
A) What is the Standard Free Energy( ∆G’o) for this reaction? Show half-reactions used to generate the reaction
above and do the actual calculation (pretty simple) in CORRECT UNITS.
B) What is the physiological ΔG’ for this reaction? No Need to Calculate
Show numbers in CORRECT UNITS in correct formula: Assume Temperature is 40 º C
C) Explain why the ΔG’ for ATP production is less favorable at the beginning of exercise than it is when ATP supplies
run low at the end of a period of exercise?
NOTE in you will not be asked to do LB plots (see below) but will need to do
Michealis-Menton enzyme kinetics as described in class for test #1.
D) Below: The enzyme creatine kinase catalyzes this reaction in a human skeletal muscle cell. Label the units for the
Lineweaver-Burke (double reciprocal) plot for this enzyme Show: Vmax, Vm/2, [S], and Km
0
1/Reaction Velocity
I
I
I
I
I
E) Below: Draw what the plot would look like if a competitive inhibitor were present and label the Vmaxi, Vmi/2, [S],
and Kmi (use an “i” to represent competitive inhibitor present)
-1/[S]
0
1/[S]
40) Extra Credit: 2 points
Draw a tripeptide and its R-groups, also label all peptide bonds (Assume pH = 7.4). Be sure that the R-groups of the
first and last amino acids attract each other at physiological pH by ionic bonds. Use no one amino acid twice.