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Biochem
ACS Q's
197
Chemistry
Undergraduate 3
12/15/2015

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Term
D-fructose is...
Definition
a ketohexose.
Term
A disaccharide is made up of two aldohexose residues that are connected by a beta (1-->1) alpha glycosidic bond. Is the disaccharide a reducing sugar?
Definition
No, the disaccharide is not a reducing sugar.
Term
How do amylose and cellulose differ from each other?
Definition
Both are polymers of glucose residues but they differ in the configuration of the glycosidic bonds.
Term
Maltose is made up of...
Definition
two D-glucose molecules.
Term
Which carbohydrate is a disaccharide?

Glucose
Amylopectin
Glycogen
Lactose
Definition
Lactose.
Term
Termites contain microbial endosymbionts that help them digest cellulose. These symbionts help termintes digest cellulose by producing enzymes that catalyze the cleavage of?
Definition
beta (1-->4) glycosidic linkages of cellulose.
Term
Compound A has the following formula: (COH)-CH2CH2-(CH2OH). Compound B has the formula: (COOH)-CH2-(CH2OH). Can either (or both) compounds have optical isomers?
Definition
Neither Compound A or B can have optical isomers.

**Optical isomers: two compounds with same number/kinds of atoms and connectivity, and different spatial arrangements.
Term
If the amino acid alanine is in a solution at pH 12, which are the predominant forms of its functional groups?
Definition
The alpha amino group is neutral and the alpha carboxyl group is in the negatively charged carboxylate form.
Term
The peptide bond that joins amino acids in a protein is actually a(n)...bond.

Ionic
Ester
Amide
Van der Waals
Definition
Amide.
Term
How many possible FOUR-based oligonucleotides can be made with the standard set of A,C,G,T, and U (e.g. five residues)?
Definition
625.

**(# residues)^(# base)=5^4=625
Term
The beta-sheet is an example of which type of structure in proteins?

Primary
Secondary
Tertiary
Quaternary
Definition
Secondary.
Term
The hydrophobic effect refers to?
Definition
The entropically driven effect that frees up more water molecules to the bulk solution when hydrophobic groups coalesce.
Term
Which of the following is an acid amino acid?

Cysteine
Valine
Lysine
Proline
Definition
Cysteine.
Term
Which of the following is an example of a saturated fatty acid?

Palmatic acid
Palmitoleic acid
Linoleic acid
Arachidonic acid
Definition
Palmitic acid.
Term
Which is NOT a function of nucleic acids?

To store genetic information
To act as catalysts
To participate in protein synthesis
To act as hormones
Definition
To act as hormones.
Term
Which of the following amino acids would likely have its side chain oriented toward the interior of a protein?

Aspartate
Lysine
Leucine
Arginine
Definition
Leucine.

**Proteins have hydrophobic cores
Term
Which of the following classes of lipids functions primarily as a storage form of energy?

Phospholipids
Glycolipids
Sphingolipids
Triacylglycerols
Definition
Triacylglycerols
Term
What is characteristic of lipids that are part of a cell membrane?
Definition
They rapidly exhibit lateral diffusion within a leaflet of the membrane.
Term
The hormone epinephrine is synthesized from which amino acid?
Definition
Tyrosine.
Term
An example of a water-soluble vitamin is...
Definition
Vitamin C.
Term
Lipases are enzymes that catalyze the cleavage of which type of bond?
Definition
Ester.
Term
What is true regarding animal fats?
Definition
They acyl tails tend to have a higher degree of SATURATION compared to plant oils.
Term
What is TRUE of RNA?

The 2' carbon of the ribose moiety is bonded to two hydrogen atoms
It generally contains the base thymine
It's biosynthesis proceeds 3' to 5'
RNA (rather than DNA) is the repository of genetic information in some biological entities
Definition
RNA (rather than DNA) is the repository of genetic information in some biological entities.
Term
A nucleoside contains a nitrogenous base and what else?
Definition
A sugar, typically ribose.
Term
In mammals, mRNA is produced from...
Definition
DNA.
Term
The PRODUCTION of mRNA is often termed what?
Definition
Transcription.
Term
What is a function of rRNA?
Definition
It (along with various proteins) forms the ribosome, and it participates in the catalytics steps of protein synthesis.
Term
What is a characteristic of enzymes?
Definition
They lower the activation energy to allow a particular reaction to proceed at a faster rate than would otherwise be the case in the absence of the enzyme.
Term
The term ALLOSTERIC SITE referes to what?
Definition
The site on a protein or enzyme to which an effector molecules binds to elicit a change in the enzyme protein's conformation.
Term
Production of TRYPSIN facilitates the digestion of which type of food molecule?
Definition
Proteins.
Term
In enzyme kinetics, one could expect the maximal rate of an enzyme-catalyzed reaction when...
Definition
[S]>>Km
Term
The active form of chymotrypsin functions in the small intestine. Accordingly, one expects that the highest activity of this enzyme occurs at what pH value?
Definition
8.
Term
An enzymologist constructed a double-reciprocal plot from data that were collected in the absence and presence of an inhibitor. The plot showed intersecting lines at the y-intercept. What type of inhibition occurred?
Definition
Competitive.
Term
Which citric acid cycle compound is formed when isocitrate is oxidatively decarboxylated?
Definition
Alpha-ketoglutarate.
Term
The process by which glycogen is converted to glucose 1-phosphate is termed...
Definition
Glycogenolysis.
Term
Many catabolic reactions produce which form of the following cofactors?
Definition
NADH.
Term
Hyperventillation tends to...the pH of blood.
Definition
Increase.
Term
When yeast are grown ANAEROBICALLY, they produce ethanol and CO2. Metabolically, this strategy allows them to...
Definition
Regenerate NAD+.
Term
Stearic acid has 18 carbons and glucose has 6. Would metabolizing one mole of stearic acid or 3 moles of glucose provide more energy?
Definition
Metabolizing one mole of stearic acid.
Term
A STEROID HORMONE generally exerts its effects by...
Definition
Binding to a receptor (usually a transcription factor) in the nucleus of the cell.
Term
When drawn in the Fishcer (vertical) representation, a compound has a hydroxymethyl group (CH2OH) at carbon 1 (the top or uppermost carbon), a keto group (C=O) at carbon 2, a hydroxymethlene group (H-C-OH) at carbon 3 (with the hydroxyl group on the right), another hydroxymethylene group at carbon 4 (with the hydroxyl group on the left), and a final hydroxymethyl group at carbon 5. This compound is what type of molecule?
Definition
an L-ketopentose.
Term
Nonsuperimposable, non-mirror-image stereoisomers are referred to as...
Definition
Diastereomers.
Term
Which of the following amino acids is a nonessential amino acid?

Leucine
Alanine
Lysine
Tryptophan
Definition
Alanine.
Term
The isoelectric (pI) of arginine is 10.76. If a solution containing arginine was buffered at a pH of 7, what would be the net charge of the arginine molecules?
Definition
+1.
Term
If the sequence of one strand of DNA is AGTCAT, what would be the corresponding, complementary sequence on the other strand?
Definition
ATGACT.
Term
PHOSPHATASE enzymes catalyze what class of enzymatic reactions?
Definition
Hydrolysis reaction of phosphoryl groups on certain proteins or metabolites.
Term
What best describes the nitrogenous base thymine?
Definition
A pyrimidine with keto and methyl groups.
Term
How many hydrogen bonds link an adenine of one strand of DNA to a thymine on the other strand?
Definition
Two.
Term
Zymogen is the name for...
Definition
The inactive form of an enzyme.
Term
A molecule has three fused six-member rings, a fourth five-member ring (also fused to the other three rings), an alkyl side chain, and a hydroxyl group. To what class molecules does the molecule belong?
Definition
Sterols.
Term
What is an example of an ANABOLIC process?
Definition
Conversion of acetyl-CoA to palmitate.
Term
During the citric acid cycle, the intermediate alpha-ketoglutarate is decarboxylated and converted to...
Definition
Succinyl-CoA.
Term
Cyclic AMP (cAMP) is a second messenger that...
Definition
Activates protein kinase A.
Term
A graph of enzyme activity versus temperature typically shows...
Definition
An initial increase and then a decrease as the temperature rises.
Term
Oxidative phosphorylation produces...
Definition
Water.
Term
GCU is codon that specifies the amino acid alanine. What is another codon for alanine?
Definition
GCA.
Term
Arachidonate is...
Definition
A precursor of prostaglandin H2.
Term
The corin ring in cobalamin-dependent proteins is...
Definition
Part of an essential cofactor for these proteins.
Term
Ubiquinone functions in...
Definition
Oxidative phosphorylation.
Term
In fatty acid biosynthesis, which of the following occurs?

- A hydratase catalyzes the addition of the elements of water to a double bond in one of the intermediates
- A secondary alcohol in one of the intermediates is oxidized to a ketone
- A triple double-bond is introduced into one of the intermediates by a dehydrogenase enzyme
- A transthioesterification reaction places the acetyl group of acetyl-CoA onto the sulfur of a cysteine residue on a fatty acid synthase
Definition
A transthioesterification reaction places the acetyl group of acetyl-CoA onto the sulfur of a cysteine residue on a fatty acid synthase
Term
Molecular action within biologic membranes is best characterized by what?
Definition
Lipid molecules exhibit lateral movement within the membrane bilayer.
Term
In biologic membranes, integral proteins and lipids interact mainly by...
Definition
Hydrophobic interactions.
Term
Lateral movement of membrane proteins can be visualized by following the movement of fluorescent-labeled proteins at 37C in heterokaryons (artificial hybrids of mouse and human cells). If the incubation temperature is decreased by about 35C, the lateral movement of the proteins is not observed. What best explains the temperature effect?
Definition
The lateral movement of membrane proteins is influenced by membrane fluidity, which is low at the lower temperature.
Term
What best describes what is meant by the ion product of water?
Definition
The product of the concentrations of hydrogen ions and hydroxyl ions in water or in aqueous solutions of electrolytes.
Term
A buffer solution contains a mixture of a weak acid at a concentration of 10 mM, and its potassium salt has a concentration of 1 mM. The pH of the buffer solution is approximately...
Definition
pKa' -1.
Term
If 0.1 M solutions of sodium dihydrogen phosphate (NaH2PO4) and disodium hydrogen phosphate (Na2HPO4) are mixed toether in equal proportions, what is the pH of the mixture? (Note that the pKa'-values of orthophosphoric acid (H3PO4) are 2.0, 6.8, and 12.0)
Definition
6.8
Term
A sample of urine from a patient with ketosis contains 30 mmol of total acetoacetic acid - acetoacetate (pka'=4.8). The pH of the urine is 4.8. Assuming that Na+ is exvreted as a counter-ion with equivalent amounts of conjugate based, what is the concentration of Na+ excreted with this keto acid?
Definition
15 mmol.
Term
The pKa' of acetic acid is 4.76. What is the pH of a 0.1 M solution of acetic acid?
Definition
2.88
Term
The Henderson-Hasselbalch equation can be used to...
Definition
Calculate the degree of ionization of a weak acid with a known pKa' value in a solution of known pH.
Term
A medical student becomes extremely anxious the night before a biochemistry exam and begins to hyperventilate uncontrollably. What initial effects doesn hyperventilation have on the Pco2 and blood pH?
Definition
Pco2 decreases and pH increases
Term
What alpha-amino acid is a diamino-monocarboxylic acid?
Definition
Lysine.
Term
With the exception of glycine, all amino acids found in proteins are...
Definition
Of the L-configuration.
Term
The peptide bond has a "backbone" of atoms in what sequence?
Definition
C-C-N-C
Term
What is true about protein structure?
Definition
Globular proteins tend to fold into configurations that keep hydrophobic side chains in the interior of the molecule.
Term
A protein treated with fluorodinitrobenzene (FDNB)and subjected to acid hydrolysis yielded two different amino acids with their alpha-amino groups linked to dinitrophenyl (DNP). A reasonable explanation for this result is that...
Definition
The protein contained more than one N-terminal amino acid
Term
Which group of peptides are produced after cleavage of the following peptide with trypsin?

Met-Ala-Try-Met-Phe-Arg-Gly-Asp-Lys-Glu-Trp
Definition
Met-Ala-Try-Met-Phe-Arg
Gly-Asp-Lys
Glu-Trp

**Trp cleaves exclusively after Arg and Lys
Term
What ionic species of glutamate would be prevalent at a pH of 10?
Definition
(-)OOC-C-(CH2)2-COO(-)
|
NH2

**In a basic solution, the H atoms will be removed
Term
All of the following forces may play a role in the formation of quarternary structure EXCEPT

- hydrogen bonds
- electrostatic interactions
- hydrophobic interactions
- disulfide bridges
- peptide bonds
Definition
Peptide bonds.
Term
What is correct about oxygen binding and release by hemoglobin?
Definition
Lowering the pH accelerates the release of oxygen from oxyhemoglobin.
Term
What is involved int he formation of hydroxyproline and hydroxylysine during collagen synthesis?
Definition
Ascorbic acid (vitamin c)
Term
During muscle contraction, what does not change length?
Definition
The A band
Term
All of the statements concerning the prosthetic heme group of myoglobin and hemoglobin, protoporphyrn IX, are true EXCEPT

- In myoglobin and hemoglobin, the heme group can reversibly bind oxygen without oxidizing the ferrous form of iron (Fe+2) to the ferric form (Fe+3)
- Fe+2 in heme can form six ligand bonds, four of which bind to the protoporphyrin ring
- Free heme, unbound to myoglobin or hemoglobin, binds oxygen reversibly without oxidizing Fe+2 to Fe+3
- The fifth bond of Fe+2 of heme is to the histidine, His-F8, on the proximal side of the protoporphyrin plane
- The sixth bond of the Fe+2 can form to an oxygen between it and a histidine, His-E7, on the distal side of the protoporphyrin ring
Definition
Free heme, unbound to myoglobin or hemoglobin, binds oxygen reversibly without oxidizing Fe+2 to Fe+3
Term
What is meant by the steady-state assumption that underlies the MIchaelis-Menten relationship between substrate concentration and reaction velocity?
Definition
The rate of breakdown of the enzyme-substrate complex equals the rate of formation of the complex

**v=vmax[S]/Km+[S]
Term
From the following Lineweaver-Burk plot, what can be concluded?
Definition
When the concentration of substrate is 0.005 M, v=5.0 mol/min
Term
An allosteric modulator influences enzyme activity by...
Definition
Binding to a site on the enzyme molecule distinct from the catalytic site
Term
After ingestion, ehtanol is normally converted to acetaldehyde by the enzyme ALCOHOL dehydrogenase (ADH). Ethylene glycol, the major ingredient in antifreeze, is occasionally consumed by alcoholics as a substitute for ethanol. Ethylene glycol is also a substrate for ADH, but the aldehyde product that is formed is highly toxic. Ethanol is often administered as a treatment in cases of ethylene glycol poisoning. What is the mostly likely reason that ethanol is an effective treatment for ethylene glycol poisoning?
Definition
ADH exhibits a much lower Michaelis constant (Km) for ethanol than for ethylene glycol
Term
Which of the following statements best characterizes glucose?

- It usually exists in the furanose form
- It is a ketose
- Carbon 2 is the anomeric carbon atom
- It forms part of the disaccharide sucrose
- It is oxidized to form sorbitol
Definition
It forms part of the disaccharide sucrose
Term
The sugar residues of amylose are...
Definition
in alpha(1-->4) linkages
Term
Correct statements regarding the structure of polysaccharides includes all of the following EXCEPT

- Amylose is a linear unbranched polymer of D-glucose in a repeating sequence of alpha-1,4-glycosidic linkages
- Amylopectin is a branched polymer of D-glucose with alpha-1,4-glycosidic linkages and with alpha-1,6 branching points every 25-30 D-glucose residues
- Glycogen is a branched polymer of D-glucose with alpha-1,4-glycosidic linkages and with alpha-1,6 branching points every 8-10 D-glucose residues
- Cellulose is composed on linear chains of D-glucose units joined by alpha-1,4-glycosidic linkages
- Cellulose is not hydrolyzed by human enzyme systems
Definition
Cellulose is composed on linear chains of D-glucose units joined by alpha-1,4-glycosidic linkages
Term
If the base sequence of a segment of DNA is pCpApGpTpTpApGpC, which of the following sequences is complementary?
Definition
pGpCpTpApApCpTpG
Term
What is true of double-helical DNA?
Definition
Unless the DNA is circular, the 3' hydroxyl groups of each chain are at opposite ends of the molecule
Term
Most protein-coding sequences are found in which class of DNA?
Definition
Nonrepetitive sequences
Term
If a sample of DNA is found to have the base composition (mole ratiosO of adenine, 40; thymine, 22; guanine, 19, and cytosine, 19, what conclusion can be drawn?
Definition
The DNA is single-stranded.
Term
If the cytosine content of double-helical DNA is 20% of the total bases, the adenine content would be...
Definition
30%
Term
What is true concerning characteristics of histones?
Definition
Evolutionarily, they are very highly conserved proteins.
Term
All of the following statements about RNA are true EXCEPT

- The sugar group o f ribonucleotides has an OH group at the 2' position
- In RNA helices, adenine (A) can base pair with uracil (U) through two hydrogen bonds
- The mole fraction of A equals the mole fraction of U
- Ribonucleotides are linked into a polar molecule by phosphodiester bonds between the 3' hydroxyl on the sugar of one ribonucleotide through a phosphate to the 5' hydroxyl on the sugar of another ribonucleotide
Definition
The mole fraction of A equals the mole fraction of U
Term
All of the following statements describe phophoglycerides EXCEPT

- They are both amphipathic and amphoteric
- They aris from glycerol 3-phosphate
- They are found in cell membranes
- They are a major store of metabolic energy
- They contain two fatty acid moieties
Definition
They are a major store of metabolic energy
Term
Primarily used as a source of metabolic energy
Definition
Ketone bodies
Term
May contain a carbohydrate moiety and is present in most cell membranes
Definition
Gangliosides
Term
Is the primary lipid present in very low-density lipoproteins
Definition
Triglycerides
Term
Is derived from 5-HPETE and modulates a variety of biologic functions
Definition
Leukotrienes
Term
E. coli cells that had been cultured in alight medium containing 14N-ammonium chloride as the sole nitrogen source were transferred to a heavy medium containing 15N-ammonium chloride. After three generations of growth in the heavy medium, what will be the proprtion of dual light strands (LL), dual heavy strands (HH), and hybrid strands (LH) in the DNA duplexes?
Definition
33HH to 1LH
Term
The colinearity of gene and product clearly seen in prokaryote systems is obscured in eukaryotes because...
Definition
The coding sequences in DNA is interrupted by DNA sequences that are transcribed and then spliced out of the mRNA
Term
What best describes the action of introns?
Definition
They are excised upon processing of heterogeneous nuclear RNA (hnRNA) to messenger RNA (mRNA)
Term
The genetic codes refers to what?
Definition
The nucleotide sequences that correspond to common amino acids
Term
The "wobble" hypothesis refers to the less stringent base-pairing specificity of the...
Definition
5'-end of the anticodon
Term
Degeneracy of the genetic code means that...
Definition
A given amino acid can be coded for by more than one base triplet
Term
All of the following statements concerning prokaryotic ribosomes are true EXCEPT

- They are composed of two subunit particles with sedimentation coefficients of 30S and 50S
- They are composed of about 65% RNA and about 35% protein
- They have a sedimentation coefficient of 70S
- They have all their protein in the 50S subunit
- Their proteins are typically basic
Definition
They have all their protein in the 50S subunit
Term
Which mutation of the sequence GATCCT is the possible result of a TRANSITION mutation. A transition mutation is one in which a purine is replaced by another purine or a pyrimidine by another pyrimidine.
Definition
GGTCCT
Term
Which of the following sequences is most likely to be a restriction enzyme recognition site?

- CGGC
- CGC
- CTAATG
- GTCGAC
- There is insufficient information
Definition
GTCGAC
Term
Restriction enzymes are best described as...
Definition
They make sequence-specific cuts in both strands of duplex DNA
Term
If a reaction is at equilibrium, the free-energy change (deltaG) is...
Definition
Equal to zero.
Term
The normal concentrations of G6P and F6P in human erythrocytes are 1e-5 M and 1e-6 M, respectively. If the standard free energy change for the reaction G6P-->F6P is +0.4 kcal/mol, what is correct?
Definition
The free energy change is about -1.0 kcal/mol
Term
The standard free energy change for the conversion of compound X to compound Y is +1.4 kcal/mol at 37C. What most closely approximates the equilibrium ratio of the concentration of X to that of Y?
Definition
10:1
Term
If an enzymatic reaction has a standard free energy change of -5 kcal/mol, the equilibrium constant is...
Definition
Greater than 1
Term
The values of the standard free energy change for the hydrolysis of ATP and creatine phosphate are -7.4 kcal/mol and -10.2 kcal/mol, respectively. How then can you account for the formation of creatine phosphate from ATP and creatine catalyzed by creatine kinase?
Definition
The free energy change of the reaction is dependent upon the concentration of reactants as well as on the standard free energy change values of hydrolysis
Term
What compound has a higher group transfer potential for phosphate than ATP?
Definition
2-phosphoenolpyruvate
Term
What parameters can be determined from a knowledge of the standard oxidation-reduction potential for an oxidation-reduction reaction?
Definition
The standard free energy change of the reaction
Term
If an redox rxn with a 2e(-) transfer has a standard reductions potential of +0.3 volts, what's the free energy change under standard conditions?
Definition
-13.8 kcal/mol

deltaG*=-n*F*deltaE | F=23.1 kcal/mol
Term
Pyridoxal phosphate is a cofactor for what enzymatic reactions?
Definition
Aminotransferase
Term
Hydrophilic hormones are best described by...
Definition
They bind to cell-surface receptors, which transmit a signal to the interior of the cell
Term
The role of Gs protein in the activation of adenylate cyclase is best described as...
Definition
The Galpha subunit of Gs protein exchanges GDP for GTP, dissociates from the Gbeta,gamma subunits, and activates adenylate cyclase
Term
Which of the following statements about cAMP is true?
Definition
Levels of cAMP quickly decline because it is hydrolyzed by cyclic nucleotide phosphodiesterase (PDEase)
Term
Phospholipase C is best described by which action?
Definition
It hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP2) to inositiol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), which are both second messengers
Term
Which of the following best describes the mechanism of action of insulin on target cells?
Definition
Insulin binds to a transmembrane receptor at the outer surface of the plasma membrane, which activates the tyrosine kinase that is the cytosolic domain of the receptor
Term
A hormone response element is best defined by which of the following statements?
Definition
It is the DNA sequence to which a specific hormone-receptor complex binds
Term
In anaerobic glycolysis, 2 moles of inorganic phosphate (Pi) are used per mole of glucose consumed. Which of the following enzymes catalyzes the uptake of Pi?
Definition
Glyceraldehyde 3-phosphate dehydrogenase (G3PDH)
Term
When one mole of glucose is processed through glycolysis, the products are...
Definition
2 mol ATP
2 mol pyruvate
2 mol NADH
Term
When one mole of glucose is processed through glycolysis and the lactate dehydrogenase reaction, the products are...
Definition
2 mol ATP
2 mol lactate
2 mol NAD+
Term
The three "irreversible" reactions of glycolysis are catalyzed by which three enzymes?
Definition
Hexokinase
Phosphofructokinase
Pyruvate kinase
Term
It is the major regulatory enzyme of glycolysis
Definition
Phosphofructokinase
Term
AMP is an activator of this enzyme
Definition
Phosphofructokinase
Term
This enzyme catalyzes the interconversion of dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP)
Definition
Triose phosphate isomerase
Term
The reaction that this enzyme catalyzes produces a "high energy" phosphate without the involvement of ADP or ATP
Definition
Enolase
Term
Which of the reactions of the citric acid cycle listed below results in the formation of a "high energy" phosphate compound?
Definition
Succinyl-CoA synthetase
Term
What enzyme is tightly associated with the inner mitochondrial membrane?
Definition
Succinate dehydrogenase
Term
The enzyme that catalyze an anaplerotic reaction in the citric acid cycle is...
Definition
Pyruvate carboxylase
Term
A patient is found to be deficient in activities of both pyruvate dehydrogenase (PDH) and alpha-ketoglutarate dehydrogenase. What is the most likely explanation for this finding?
Definition
The patient possesses a genetic defect in the E2 subunit of PDH
Term
An individual from a genetic defect in the E2 subunit which decrease the activity of the pyruvate dehydrogenase (PDH) complex. Which of the following is a likely symptom of this disorder?
Definition
Above normal levels of serum lactate
Term
An individual suffers from a genetic defeat in the E2 subunit which DECREASES the activity of the PDH complex. Which of the following treatments is most likely to be beneficial in this case?
Definition
Restriction of dietary carbohydrates
Term
All of the following compounds are intermediates of the citric acid cycle EXCEPT

- Isocitrate
- Malate
- Oxaloacetate
- Pyruvate
- Succinate
Definition
Pyruvate
Term
Pyruvate dehydrogenase (PDH) activity is regulated by all of the following EXCEPT

- Covalent modification
- Availability of substrates
- Product inhibition
- Insulin
- A cytosolic protein kinase
Definition
A cytosolic protein kinase
Term
It's possible for a variety of substrates to use a common pathway for the transfer of electrons to oxygen because...
Definition
Many of the substrates are oxidized by enzymes linked to oxidized nicotinamide or flavin-adenine dinucleotide
Term
The mitochondrial electron transport chain carriers are located...
Definition
In the inner mitochondrial membrane
Term
Some of the free energy released in the mitochondrial electron transport chain can be harnessed to the formation of ATP. How many molecules of ATP can be formed per pair of electrons transferred from reduced nicotinamide adenine dinucleotide (NADH) to oxygen?
Definition
2.5
Term
The uncoupling oxidative phosphorylation in a mitochondrial system describes which of the following actions
Definition
The phosphorylation of ADP stops but oxygen uptake continues
Term
The chemiosmotic coupling hypothesis of oxidative phosphorylation proposes that adenosine triphosphae is formed because...
Definition
A proton gradient forms across the inner membrane
Term
All of the following electron carriers are components of the mitochondrial electron transport chain EXCEPT
Definition
Nicotinamide-adenine dinucleotide phosphate (NADP+)
Term
The cost in high-energy phosphate bonds for the formation of 1 mol of glucose from pyruvate is...
Definition
6 mol of ATP
Term
The regulation of the activities of which pair of enzymes provides an example of reciprocal control of opposing metabolic pathways?
Definition
Fructose 1,6-bisphosphatase (F1,6BPase) and phosphofructokinase
Term
A deficiency in the vitamin biotin leads to a deficiency in the activity of which enzyme of the gluconeogenic pathway?
Definition
Pyruvate carboxylase
Term
In the sequence of reactions that convert pyruvate to glucose in the cells capable of gluconeogenesis, three reactions are used to bypass enzymes of the glycolytic pathway in which glucose is converted to pyruvate. All of the following enzymes fall into this category EXCEPT

- Pyruvate carboxylase
- Pyruvate dehydrogenase
- Phosphoenolpyruvate carboxykinase (PEPCK)
- Fructose 1,6-bisphosphatase (F1,6-BPase)
- Glucose 6-phosphatase (G6Pase)
Definition
Pyruvate dehydrogenase
Term
What types of linkages are present between the glucose units of glycogen?
Definition
alpha-1,4 and alpha-1,6 linkages
Term
Glycogen is stored in the cells as...
Definition
Granules, which also contain enzymes that catalyze its formation and degradation
Term
The greatest amount of body glycogen can be found in which of the following human tissues?
Definition
Skeletal muscle
Term
Free glucose is formed during glycogenolysis from...
Definition
Glucose residues in 1,6 linkage to the main chain
Term
The acetyl groups required for cytoplasmic fatty acid synthesis appear in the cytoplasm as a result of the activity of...
Definition
Citrate lyase
Term
The removal of two-carbon units from a fatty acyl-CoA involves four sequential reactions. What best describes the sequence?
Definition
Dehydrogenation, hydration, dehydrogenation, cleavage
Term
Beta oxidation of phytanic acid, a fatty acid derived from chlorophyll and found in cow's milk, cannot take place without prior oxidation at the alpha carbon. Which statement best explains the requirement for alpha oxidation?
Definition
The beta carbon in phytanic acid is blocked by a methyl group
Term
Which amino acid is an essential amino acid; that is, which must be ingested on a daily basis by humans?
Definition
Leucine
Term
What amino acids are catabolized to a common citric acid cycle intermediate?
Definition
Proline
Glutamate
Glutamine
Arginine
Term
In the transamination of amino acids all of the following are true EXCEPT

- Pyridoxal phosphate is a coenzyme/prosthetic group
- The reaction is tightly controlled by allosteric effectors
- The amino acid acceptor is typically an alpha-keto acid
- Ammonia is neither consumed nor produced
- In the catabolism of most, but not all, amino acids, transamination precedes all catabolic changes in the carbon skeleton
Definition
The reaction is tightly controlled by allosteric effectors
Term
Which of the following essential dietary factors is a precursor for a compound that can act as a carrier of one-carbon fragments at different levels of oxidation?

- Methionine
- Thiamine
- Folic acid
- Biotin
- Pryidoxine
Definition
Folic acid
Term
The posprandial state is characterized by...
Definition
HIGH blood levels of glucose and HIGH levels of insulin
Term
High levels of citrate reduce the activity of which pathway?
Definition
Glycolysis
Term
Which of the following metabolic pathways is correctly matched with the key enzyme that regulates that pathway?

- Pentose phosphate pathway - glucokinase
- Glycolysis - fructose 1,6-bisphosphatase
- Gluconeogenesis - phosphofructokinase
- Fatty acid synthesis - acetyl-CoA carboxylase
- TCA - glucose 6-phosphate dehydrogenase
Definition
Fatty acid synthesis - acetyl-CoA carboxylase
Term
What action occurs after several days of starvation?
Definition
Ketone bodies are released by the liver into the blood
Term
Translation of the repeating sequence CAA in a cell-free protein synthesizing system produced three homopolypeptides: polyglutamine, polyasparagine, and polythreonine. If the codons for glutamine and asparagine are CAA and AAC, respectively, what is a codon for threonine?
Definition
ACA
Term
Which of the 20 amino acids coded for in DNA is an imino acid?
Definition
Proline
Term
The systems involved in the beta oxidation of fatty acids and in their biosynthesis are similar in the...
Definition
Use of repetitive series of reactions for the sequential transfer of two-carbon units
Term
What regulatory action involves a reversible covalent modification of an enzyme?
Definition
Phosphorylation of a serine hydroxyl on the enzyme
Term
The most important source of reducing equivalents for fatty acid synthesis in the liver is...
Definition
The pentose phosphate pathway
Term
The formation of chylomicrons takes place...
Definition
In the intestinal mucosal cells where they contains about 85% TAGs
Term
Adenosine triphosphatase (ATPase) activity needed for muscle contration is a component of...
Definition
the amino-terminal globular head of myosin
Term
A 2-day old patient exhibits extreme lethargy and hyperventillation. Blood analysis indicated normal blood urea nitrogen (BUN) levels, very high levels of ammonia, partial pressure of carbon dioxide (Po2) of 25 mmHg, a bicarbonate concentration of 24 mM, and a pH of 7.5. Urine analysis revealed extremely high levels of orotice acid and no detectable citruline.

This patient likely suffersf rom a defect in which metabolic pathway?
Definition
Urea cycle
Term
A 2-day old patient exhibits extreme lethargy and hyperventillation. Blood analysis indicated normal blood urea nitrogen (BUN) levels, very high levels of ammonia, partial pressure of carbon dioxide (Po2) of 25 mmHg, a bicarbonate concentration of 24 mM, and a pH of 7.5. Urine analysis revealed extremely high levels of orotice acid and no detectable citruline.

Which metabolites is expected to be found in high levels in the blood of this patient?
Definition
Glutamine
Term
A 2-day old patient exhibits extreme lethargy and hyperventillation. Blood analysis indicated normal blood urea nitrogen (BUN) levels, very high levels of ammonia, partial pressure of carbon dioxide (Po2) of 25 mmHg, a bicarbonate concentration of 24 mM, and a pH of 7.5. Urine analysis revealed extremely high levels of orotice acid and no detectable citruline.

Which is an essential amino acid for this patient?
Definition
Arginine
Term
To what metabolic intermediate is ethanol normally converted?
Definition
Acetyl-CoA
Term
A true characteristic of the Edman reaction is...
Definition
The reaction can be carried out repeatedly on the same sample of the peptide for sequence determination
Term
What term best describes an enzyme that catalyzes the following reaction:

Glucose + ATP<-->Glucose 6-phophate + ADP
Definition
Kinase
Term
What is the only component of the ETC not firmly embeded int he inner mitochondrial membrane?
Definition
Cytochrome C
Term
What specific effect does citrate have on the activity of phosphofructokinase?
Definition
The ratio Vmax/Km is lower in the presence of citrate
Term
Which metabolic pathway also possesses a key enzyme that is allosterically regulated by citrate?
Definition
Fatty acid synthesis
Term
The enzymes of oxidative phosphorylation and ETC are located in the inner mitochondrial membrane. Where are the analogous bacterial enzymes found?
Definition
Plasma membrane
Term
Fetal hemoglobin (Hb F) is able to bind oxygen well because...
Definition
Hb F does not bind 2,3BPG well
Term
Enzymes increase the rates of reactions by...
Definition
Decreasing the energy of activation
Term
Specific, radioactive labeling of the RNA (not the DNA) of a cell can be done by feeding the cell radioactive...
Definition
Uridine
Term
In the mitochondrial ETC, carriers with a more positive reduction potential oxidize carries with a more negative reduction potential. The reduction potential of cytochrome c is more...
Definition
Positive than that of FAD --> FADH2 + 2e-
Term
If the substrate concentration in an enzyme-catalyzed reaction is equal to 1/2Km, the initial reaction velocity will be...
Definition
1/3*Vmax

v=vmax*[S]/Km+[S]
Term
What enzyme provides a link between glycolysis and the citric acid cycle?
Definition
Pyruvate dehydrogenase
Term
All of the following lipids are major components of animal membranes EXCEPT

- Phopholipids
- Cholesterol
- Prostaglandins
- Glycolipids
Definition
Prostaglandins
Term
All of the following statements concerning the peptide bond are true EXCEPT

- It has a partial double-bond character
- It is polar
- It cannot rotate freely
- It is planar
- It is CIS in the alpha-helix
Definition
It is cis in the alpha-helix
Term
Generally accepted features of biologic membranes include all of the following EXCEPT

- Asymmetric arrangement of lipids
- Rapid diffusion of inorganic ions across the lipid bilayer
- Lateral diffusion of lipids
- Lateral diffusion of integral and peripheral proteins
- Infrequent transverse ("flip flop") movement of lipids from one face of the bilayer to the other
Definition
Rapid diffusion of inorganic ions across of the lipid bilayer
Term
All of the following are properties of cellular membrane proteins EXCEPT

- They may have catalytic activity
- If peripheral, they are amphipathic
- If integral, they can span the width of the membrane
- They can move laterally in the plane of the membrane
- If peripheral, they can be removed from the membrane without disrupting the membrane structure
Definition
- If peripheral, they are amphipathic
- If integral, they can span the width of the membrane
Term
What is NOT a characteristic of the lateral movement of integral membrane proteins?
Definition
It is restricted by an increase in temperature
Term
What is NOT true regarding the structure of polysaccharides?
Definition
Cellulose is composed of linear chains of D-glucose units joined by alpha-1,4-glycosidic linkages
Term
What is NOT true regarding the urea cycle?
Definition
The immediate precursor of urea in the cycle is ornithine
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