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What regulatory post-translational modification occurs on serinethreonine, and tyrosine residues?
Phosphorylation
Sickle cell anemia is caused by a mutation in one of the genes encoding hemoglobin. What amino acid substitution results from the mutation?
At position six of the beta chain, valine is substituted for glutamate.
What level of protein structure is a beta sheet?
Secondary
Which statement best describes the amino acid substitution responsible for sickle cell anemia?
The substitution of valine for glutamate is a non-conservative substitution.
What is the quaternary structure of the heart's creatine phosphokinase?
Heterodimer
one isoform from muscle and one isoform from brain MB is useful in determining heart attacks as it is unique to heart and released into serum
Which amino acid(s) contain sulfur?
Methionine, cysteine
What effect does the mutation which causes sickle cell anemia have on hemoglobin's migration in a non-denaturing electrophoretic gel?
Hemoglobin from a sickle cell anemia patient will migrate towards the anode faster than hemoglobin from a person without the disease.
The conversion of glucose 6-phosphate to glucose 1-phosphate has a ∆G0of +1.65 kcal/mol. If we start with equal concentrations of glucose 6-phosphate and glucose 1-phosphate in solution, which product will accumulate?
Glucose 6-phosphate
hat secondary messenger is bound to an active heterotrimeric G protein's alpha subunit?
GTP
Enzymes reduce the activation energy required for a reaction. How do enzymes reduce activation energy?
Ensure proximity and orientation of substrates, stabilize transition states, ensure specificity of substrates and products
Chymotrypsin is a protease which acts to break down proteins during food digestion. What class of enzyme is chymotrypsin?
Hydrolase
How does a competitive inhibitor alter an enzyme's kinetics?
Increases Km
What effect does decreasing substrate concentration have on the energetics of a reaction?
The reaction becomes less energetically favorable.
Match the part of the pathway with the mechanism of regulation.

Inactivation of heterotrimeric G protein
Hydrolysis of GTP
Match the part of the pathway with the mechanism of regulation.

Activation of protein kinase A
Dissociation of regulatory subunits
Match the part of the pathway with the mechanism of regulation

Activation of glycogen phosphorylase kinase
phosphorylation by protein kinase A
Match the part of the pathway with the mechanism of regulation

Activation of adenylate cyclase
Conformational change by binding another protein
Match the part of the pathway with the mechanism of regulation

Activation of phosphoglucomutase
Increase in enzyme's substrate
Match the part of the pathway with the mechanism of regulation

Activation of heterotrimeric G protein
Exchanges GDP for GTP
Aspirin is a suicide inhibitor. What effect would aspirin have on the kinetics of cyclooxygenase in an in vitro assay.
lower Vmax
The terminal oxidation of fuel to CO2 is a __________________ process.
catabolic
The pyruvate dehydrogenase complex converts pyruvate to acetyl CoA, linking glycolysis to the tricarboxylic acid cycle. How is pyruvate dehydrogenase inactivated?
Pyruvate dehydrogenase is inactivated by phosphorylation of serine residues of the E1α subunits by pyruvate dehydrogenase kinase. PDH kinase is activated by acetyl CoA and NADH, and inhibited by pyruvate and ADP.
How many mols of phosphoanhydride bonds are generated if one mol of acetyl CoA is oxidized to CO2 by the TCA cycle, and all the reduced products are utilized by the electron transport chain?
10
the products of oxidation of one of acetyl CoA in the tricarboxylic acid cycle are 3 NADH + H+, 1 FAD(2H), and 1 GTP.
Which cofactor accepts two electrons as a hydride ion (H-) in oxidation / reduction reactions?
NAD+

FAD and FMN accept electrons singly, from different atoms, e.g. in double bond formation.
Which of the following enzymes is not an enzyme of the tricarboxylic acid cycle?
pyruvate carboxylase

Pyruvate carboxylase catalyzes the conversion of pyruvate to oxaloacetate, an anaplerotic reaction.
Which enzyme is regulated by allosteric mechanisms?
isocitrate dehydrogenase

Isocitrate dehydrogenase is regulated allosterically. ADP binding to one subunit activates other subunits and decreases the enzyme's Km for substrate.
Which enzyme of the TCA cycle is a member of the electron transport chain and uses the cofactor FAD?
succinate dehydrogenase

Succinate dehydrogenase is complex II of the electron transport chain. Upon oxidaiton of succinate to fumarate, it reduces FAD to FAD(2H). The energy obtained by oxidation of FAD(2H) is used to generate a proton gradient across the inner mitochondrial membrane; the proton gradient is in turn used to generate ATP.
What are consequences of acquired or inherited pyruvate dehydrogenase deficiency?
lactic acidosis, inability to convert pyruvate to acetyl CoA, impaired brain development, all symptoms of Leigh's disease
How does ATP cross the inner mitochondrial membrane from the matrix to the intermembrane space?

antiporter
ATP travels from the matrix to the intermembrane space through ANT, an antiporter. While ATP is transported out of the matrix, ADP is transported into the matrix.
Adaptive thermogenesis is an example of. . .

protein uncoupling
Adaptive thermogenesis is a mechanism of generating heat without generating or consuming ATP. The hormone norepinephrine stimulates UCP1 (uncoupling protein 1) to form a proton pore on the inner mitochondrial membrane, allowing the electron transport chain to oxidize NADH and FAD(2H) to O2 for the generation of heat. The UCP1 then allows protons to pass from the intermembrane space back into the matrix, bypassing ATP synthase. Adaptive thermogenesis is an example of protein uncoupling.
Which component of the electron transport chain is not a protein?
Coenzyme Q

(CoQ, a.k.a. ubiquinone) is an membrane soluble organic molecule which transfers electrons from NADH dehydrogenase (complex I) and succinate dehydrogenase (complex II) to the cytochrome b-c1 complex (complex III).
Cytochrome oxidase binds O2, the final electron acceptor in the electron transport chain. Hemoglobin and myoglobin also bind O2. Which of the following statements best describes the relationship of O2 binding affinities for the three proteins?
Km hemoglobin > Km myoglobin > Km cytochrome C oxidase
How many ATP can be generated from one NADH entering the electron transport chain?
2.5

One NADH traversing the ETC pumps ten protons from the matrix across the inner mitochondrial membrane.
How many ATP can be generated from one FAD(2H) traversing the electron transport chain?
1.5

One FAD(2H) traversing the ETC pumps six protons from the matrix across the inner mitochondrial membrane
Match the enzyme name with its position in the electron transport chain:

Complex I
Complex II
Complex III
Complex IV
Complex V
Complex I = NADH dehydrogenase
Complex II = succinate dehydrogenase
Complex III = cytochrome b-c1 complex
Complex IV = Cytochrome C Oxidase
Complex V = ATP synthase
Why are diseases caused by mitochondrial DNA mutations often heterogenous in their presentation?
mtDNA is present in multiple copies per mitochondria, and there are multiple mitochondria per cell.

Therefore, the ratio of mutant and normal DNA can vary from person to person, cell to cell, and mitochondria to mitochondria.
Match the regulatory mechanism with the step in the glycolytic pathway.

hexokinase
phosphofructokinase - 2
pyruvate kinase
lactate dehydrogenase
phosphofructokinase - 1

hexokinase=regulated [substrate] and [product]
phosphofructokinase - 2=regulated [substrate] and [product]
pyruvate kinase
lactate dehydrogenase=regulated [substrate] and [product]
phosphofructokinase - 1=allosteric regulation
Which choice(s) best describes the Cori cycle?


-The Cori cycle takes lactate produced by anaerobic glycolysis in red blood cells and converts it to glucose in the liver.
-The Cori cycle results in a net consumption of four ATP
-The Cori cycle is a sequence of anaplerotic reactions
-the Cori cycle involves flux of lactate between the kidneys and the central nervous system
-The Cori cycle refers to the period between 1987's "The Lost Boys" and 1989's "Dream a Little Dream"; both movies featured Corey Feldman and Corey Haim.
-The Cori cycle takes lactate produced by anaerobic glycolysis in red blood cells and converts it to glucose in the liver.
-the Cori cycle results in a net consumption of four ATP (costs 6 in liver, earns 2 in RBC)
A patient with lactic acidosis has an elevated ratio of blood [lactate] to [pyruvate]. What could be a cause of the condition?

-pyruvate dehydrogenase deficiency
-high carbohydrate diet
-low carbohydrate diet
-pyruvate carboxylase deficiency
-hypoxia
hypoxia

In cases of lactic acidosis with an elevated [lactate]/[pyruvate] (>25), the activity of lactate dehydrogenase is driven by an elevated concentration of NADH + H+. This suggests that there is a defect in an enzyme or pathway which oxidizes NADH + H+. Hypoxia is a lack of oxygen. Without molecular oxygen as a final acceptor of electrons via complex IV, electron flux throught the entire electron transport chain ceases, and the oxidation of NADH + H+ by complex I is blocked.
Glycolysis occurs in the cytosol and produces NADH + H+, but the inner mitochondrial membrane is impermeable to NADH. There are two mechanisms to transmit the reducing equivalents of NADH from the cytoplasm. What is the net equation for the malate/aspartate shuttle?
NADH(cytosol) + NAD+(matrix) ---> NAD+(cytosol) + NADH(matrix)

The malate/aspartate shuttle results in the transfer of electrons from NADH produce in the cytoplasm to NAD+ in the matrix. The glycerol 3-phosphate shuttle serves a similar purpose, but it transfers electrons to FAD in the matrix.
How many mol of ATP are generated through the complete aerobic respiration of one mol of glucose, if the malate / aspartate shuttle is used?
32
If a patient with lactic acidosis has elevated blood lactate but a normal ratio of lactate to pyruvate, what is a potential cause for the condition?

-exposure to cyanide
-exposure to retenone
-genetic defects in ETC proteins
-hypoxia
-pyruvate dehydrogenase deficiency
pyruvate dehydrogenase deficiency

In cases of lactic acidosis where the blood [lactate]/[pyruvate] ratio is normal (~25), this indicates that the lactate dehydrogenase activity is driven by the elevated concentration of pyruvate, not an increase in NADH + H+. Thus the condition may be caused by a deficit in one of the enzymes which remove pyruvate, such as pyruvate dehydrogenase or pyruvate carboxylase.
Which statement describes the end result of glucagon binding to its transmembrane receptor?

-pyruvate kinase is activated and glycogen phosphorylase kinase is inactivated
-pyruvate kinase and glycogen phosphorylase kinase are both inactivated
-pyruvate kinase and glycogen phosphorylase kinase are both activated
-adenylate cyclase is inactivated by heterotrimeric G protein's beta subunit
-pyruvate kinase is inactivated and glycogen phosphorylase kinase is activated
-pyruvate kinase is inactivated and glycogen phosphorylase kinase is activated

Glucagon is a hormone of the "fasted" state; it is produced by A cells of the pancreas. When glucagon binds its 7 transmembrane domain receptor on hepatocytes, it activates heterotrimeric G protein's alpha subunit, which activates adenylate cyclase, which produces cAMP, which binds to the regulatory subunits of protein kinase A. PKA's regulatory subunits dissociate, allowing the active catalytic subunits to phosphrylate glycogen phosphorylase kinase and pyruvate kinase. Glycogen phosphorylase kinase is activated by phosphorylation and leads to the production of glucose from glycogen. Phosphorylation of pyruvate kinase inactivates the enzyme, because the glucose produced from glycogen must be made available to other tissues of the body and not consumed by the hepatocyte.
How many mols of ATP are generated from one mol of glucose undergoing anaerobic glycolysis?
2
Which source of stored fuel has the most rapid turnover rate in the body?
fatty acids

180 times in a 12 hour period
The first step in fatty acid degradation is "activating" the fatty acid. What molecule is linked with the acyl chain to activate it?
coenzyme A
What molecules will be generated from beta oxidation of a 19 carbon saturated fatty acid?
8 acetyl CoA and 1 propionyl CoA
A person with an average body type drinks 1L of beer with an alcohol content of 5%. What volume of ethanol is available to distribute to the tissues of the person's body?
50mL
What is the final electron acceptor when ethanol is oxidized to acetaldehyde by the microsomal ethanol oxidizing system?
molecular oxygen

-Molecular oxygen is the final electron acceptor, and is reduced to water. In the process, NADPH is oxidized to NADP+.
How many mols of ATP are generated per mol of ethanol metabolized through the MEOS?
8

The microsomal ethanol metabolizing system generates 8 ATP for each ethanol metabolized. This is five less than ethanol metabolism through alcoholdehydrogenase.
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