Biochemistry Final Exam

Beta strands have how many base pairs per turn?

7

The pKa's for phosphoric acid are 2.1, 7.2, and 12.7. At a physiological pH of 7.4, which of the following species is the major species? A. HPO4 2- B. H2PO4 1- C. HPO4 2- D. H3PO4 E. H3PO4

A or C. HPO4 2-

At pH 3, the proton concentration is: A. 0.001 M B. 0.01 M C. 0.1 M D. 0.0001 M E. 3 M

A. 0.001 M

If the pKa of the histidine side chain is 6, what is the fraction of histidine that is produced at pH 7? A. 1/11th B. 10/11th C. 1/100th D. 99.999% E. 50%

A. 1/11th

You are purifying a protein. If the total amount of protein is 16 g before purification and 4 g after, and the total activity is 100 units before purification and 50 units after, how much did the specific activity increase? A. 2-fold B. 4-fold C. 3-fold D. 8-fold E. 160,000,000 fold

A. 2-fold

Ideally, water can make up to _____ hydrogen bonds to other water molecules. A. 4 B. 3 C. 2 D. 1 E. 0

A. 4

The pKA's of The carboxylic acid is found in the amino side chains are: A. 6-7 B. 17-18 C. 9-10 D. 3-4 E. 1-2

A. 6-7

We learned in class about Euhlers-Danos Syndrome (EDS) and postural orthostatic tachycardia syndrome (POTS), which often occur together. Patients have an usual flexibility, bouts of extreme exhaustion, and will tend to pass out from low blood pressure when they stand suddenly. This issue can be caused by: A. A genetic defect leading to faulty collagen production B. A lack of antioxidants leading to Cystine oxidation C. Vitamin deficiency D. A defect in hemoglobin E. A lack of essential amino acids in the diet

A. A genetic defect leading to faulty collagen production

Which of the following is an example of a secondary protein structure? A. A helix B. Amino acid C. Fatty acid D. Triglyceride E. Dipeptide

A. A helix

In the peptide Ala-Try-Gly-Phe, the N-terminal residue is: A. Alanine B. Tryptophan C. Glycine D. Aspartic acid E. Phenylalanine

A. Alanine

Dialysis is a technique that: A. Allows large molecules or cells to be retained, while small molecules are removed from a solution B. Selectively precipitates proteins C. Denatures proteins, then renatures them D. Separate molecules based on isoelectric point E. Causes your little sister to call her friends on her phone all the time (she is such a dial-y sis).

A. Allows large molecules or cells to be retained, while small molecules are removed from a solution

The amino acid that is capable of forming disulfide bonds is: A. C B. M C. Q D. K E. S

A. C

When the structure of a protein is solved by nuclear magnetic resonance (NMR), cross speaks in two dimensional spectral called NOESY spectra provide what kind of information? A. Constraints on the distances between proteins B. The number of bonds between two different nuclei C. Information about electron density around a protein D. Information about neighboring proteins via the n +1 rule E. Nothing. Absolutely nothing. NMR is really a worthless technique that we should never discuss again.

A. Constraints on the distances between proteins

Peptide synthesis normally takes place attached to a solid support. This solid phase synthesis has the advantage that: A. Desired products are easily filter to purify them at each step B. The peptide is more soluble C. The protecting groups are easier to remove D. Cysteine residues are more easily oxidized E. All of the above

A. Desired products are easily filter to purify them at each step

A measure of the amount of disorder in a system is: A. Entropy, S B. Enthalpy, H C. Internal energy, U D. Gibb's free energy, G E. Haines' Fictitious Energy, F

A. Entropy, S

You are working in the biochem lab on a new experiment involving protein sequencing. Dr. Haines gives you a tetrapeptide that contains the amino acids R, G, W, & M in some order. Treatment with Edman's reagent gives PTH-glycine. Treatment with trypsin gives two products: the amino acid tryptophan and a tripeptide. Treatment with chymotrypsin gives no reaction. Treatment with cyanogen bromide gives two dipeptide products what is the sequence of the peptide? A. GMRW B. GRWM C. GMWR D. GRMW E. RGWM

A. GMRW

In isoelectric focusing, proteins separate based on their: A. Isoelectric point B. Affinity for a substrate molecule C. Size D. Shape E. Net charge at pH 1

A. Isoelectric point

Later we will study hemoglobin, which exist normally as a tetramer (four strands of polypeptide chain each fold and associate together). This is an example of: A. Quaternary structure B. Secondary structure C. Primary structure D. Tertiary structure E. Science fiction, proteins don't ever do that

A. Quaternary structure

Dithiothreitol and beta-mercapthoethanol both break disulfide bonds by: A. Reducing them B. Hydrolyzing them C. Aromatizing them D. Oxidizing them E. Acetylating them

A. Reducing them

A Ramachandran Plot: A. Shows allowed or observed peptide backbone dihedral angles B. Is a way to calculate the pKa of a weak acid C. Is a way to calculate the enthalpy of a reaction D. Shows the amino acid side chain confirmations E. Is a best-selling novel written in India

A. Shows allowed or observed peptide backbone dihedral angles

The oxyanion hole in chymotrypsin: A. Stabilizes an alkoxide intermediate B. Is a place where the substrate gets stuck, inhibiting the enzyme C. Binds bicarbonate D. Binds superoxide E. Is were the carbonyl oxygen resides in the substrate and product but not in the intermediate/transition state

A. Stabilizes an alkoxide intermediate

ATCase demonstrates sigmoidal kinetics with respect to substrate aspartate. At low aspartate concentrations, the ______ state predominates. A. T-state B. Transition C. R-state D. X-state E. Altered

A. T-state

In a MALDI-TOF mass spectrometer, the instrument scans different ions by: A. The different times they take to transverse a flight tube B. Using gel filtration media C. Pushing with magnetic fields of different strengths at different times D. Passing through a polyacrylamide gel E. Filtering ions through different sized holes in metal discs

A. The different times they take to transverse a flight tube

Which of the following amino acids has a hydroxyl group as the side chain? A. Thr B. Phe C. Gln D. Met E. His

A. Thr

Which of the following amino acids has the largest side chain? A. W B. D C. I D. A E. G

A. W

The hydrophobic effect that causes nonpolar molecules to aggregate and water because: A. Water molecules interact strongly with each other B. Hydrophobic services have a force, the hydrophobic force, between them C. Hydrophobic services have strong static dipoles that attract each other D. Hydrophobic molecules form hydrogen bonds with each other E. This isn't correct, non-polar molecules don't aggregate and water they repel each other

A. Water molecules interact strongly with each other

Your foolish lab partner forgot to put SDS in the SDS-PAGE sample buffer and running buffers. Your gel is doomed. This is due to multiple reasons, at least one of which is because: A. Without SDS, many proteins won't have the right charge to migrate into the gel B. Without SDS, the protein isn't stable and will hydrolytically degrade C. Without SDS, the quaternary structure is destroyed D. Without SDS, the proteins are unstable and denature E. ... Well, actually, it isn't doomed. SDS is it really necessary in SDS - PAGE. It just helps make the buffers foamy, and who doesn't like bubbles? Never mind the name. Probably just a mistake by whoever named it.

A. Without SDS, many proteins won't have the right charge to migrate into the gel

The rate of the hydration of CO2, as catalyzed by carbonic anhydrase, decreases dramatically below pH7. This is because: A. Zinc bound water depronates B. A lysine in the active site must be protonated for full activity C. This is impossible - enzymes never show strong pH dependence D. A histidine in the active site must be protonated for full activity E. A histidine in the active site must be deprotonated for full activity

A. Zinc bound water depronates

When the pH is equal to a weak acid's pKa, which of the following are true? A. [HA]=[A-] B. pI=pKa C. [HA]= 0M D. [HA]= 0M E. [H+]= 10^-7 M

A. [HA]=[A-]

In the Edman Degradation, A. A proteins secondary, tertiary, and quaternary structure are destroyed while the primary structure is left intact B. A protein is sequenced by identifying the N-terminal amino acid which is removed, then identifying the new N-terminal amino acid and so on in a cyclic fashion C. All peptide bonds in a protein are simultaneously hydrolyzed by strong acid D. Cyanogen bromide is used to cleave peptides after hydrophobic amino acid side chains E. Poor Edman's his life falls apart, until little is left of the man he wants was... At least I think that was the plot.

B . A protein is sequenced by identifying the N-terminal amino acid which is removed, then identifying the new N-terminal amino acid and so on in a cyclic fashion

At 100K, which of the following reactions at equilibrium (the delta H and delta S is listed for each): A. +5 KJ/ mol, 5 J/K/mol B. + 0.5 KJ/ mol, 5 J/K/mol C. -5 KJ/ mol, 5 J/K/mol D. -0.5 KJ/ mol, 0.005 J/K/mol E. -0.5 KJ/ mol, 5 J/K/mol

B. + 0.5 KJ/ mol, 5 J/K/mol

In a western blot: A. The Bradford assay is carried out on proteins spot it onto paper, so no electrophoresis is required B. A PAGE gel is transferred to special paper and stained with the help of an antibody C. DNA is used to stain protein in an SDS-PAGE gel D. And SDS-PAGE gel is dried and treated with a coomassie dye E. A three dimensional protein NMR experiment is carried out to identify all the amino acids present

B. A PAGE gel is transferred to special paper and stained with the help of an antibody

Polyclonal antibodies A. Are antibodies that catalyze chemical reactions B. Are a mixture of different antibodies that bind many different things C. Are a sample of pure antibody, all of which binds the same thing D. Are antibodies that vine to other antibodies E. Are the antibodies found in many storm troopers in last year Star Wars movie

B. Are a mixture of different antibodies that bind many different things

The catalytic triad of serine proteases is: A. Asp, Trp, Ala B. Asp, His, Ser C. Asp, Asp, Ser D. Asp, Ala, Ser E. Ala. Trp, Ser

B. Asp, His, Ser

Dr. Lynne believes that carbonic anhydrase catalyzes the hydration of carbon dioxide using a catalytic triad. This is wrong because: A. Carbonic anhydrase does not catalyze the hydration of carbon dioxide, but the dehydration of carbonic acid B. Carbonic anhydrase is a metalloenzyme, not a serine protease C. Carbonic anhydrase has only two of the three amino acids of the catalytic triad D. Carbonic anhydrase isn't actually enzyme E. Actually, it is right. Dr. Lynne is always right

B. Carbonic anhydrase is a metalloenzyme, not a serine protease

Disulfide bonds are formed in proteins with the appropriate amino acids by: A. An SN2 reaction B. Gentle oxidation C. Harsh reduction D. Harsh oxidation E. Gentle reduction

B. Gentle oxidation

When a peptide is hydrolyzed by refluxing and concentrated HCl overnight in the amino acids are analyzed by HPLC the next day, only 18 amino acids are present (along with ammonia). The two amino acids that would be expected to be missing are: A. Lys and Arg B. Gln and Asn C. Glu and Asp D. Pro and His E. Ser and Thr

B. Gln and Asn

Which of the following statements is true? A. Hemoglobins affinity for oxygen depends on pH but not partial pressure of CO2 B. Hemoglobins affinity for oxygen depends on both pH and the partial pressure of CO2 C. Hemoglobins affinity for oxygen depends on partial pressure of CO2 but not pH D. Hemoglobins affinity for oxygen depends neither on pH nor the partial pressure of CO2 E. None of the above are true

B. Hemoglobins affinity for oxygen depends on both pH and the partial pressure of CO2

Fetal hemoglobin has a ______affinity for oxygen than adult hemoglobin. A. Lower B. Higher C. Equivalnet D. Hemoglobin isn't expressed until after birth

B. Higher

An affinity label: A. Is an irreversible inhibitor that binds to an active site and makes a covalent bond with it only if the enzyme treats it as a substrate B. Is an irreversible inhibitor that binds to an active site and makes a covalent bond with it based on a reactive group C. Is a reversible competitive inhibitor

B. Is an irreversible inhibitor that binds to an active site and makes a covalent bond with it based on a reactive group

The protonation of a histidine at an alpha subunit -beta subunit interface of hemoglobin: A. Prevents BPG binding B. Makes oxygen binding pH dependent C. Prevent carbon monoxide binding D. Causes carbon dioxide to bind hemoglobin E. Hemoglobin doesn't have alpha and beta chains it is a Homotetramer

B. Makes oxygen binding pH dependent

All of the amino acids are chiral except: A. G B. P C. G and P D. Y E. W

B. P

In prion diseases, the infectious agent is: A. A small piece of RNA B. Protein that folds into a very stable structure C. A protein that becomes disordered D. A virus with the protein coat E. Dr. Primm (is is Primm's Really Intensely Opportunistic Neuropathy)

B. Protein that folds into a very stable structure

In ion-exchange chromatography with chromatography media coated with carboxymethyl groups, which of the following amino acids will elute last? A. S B. R C. A D. N E. E

B. R

The distal histidine in hemoglobin: A. Binds directly to the heme iron B. Reduces affinity for carbon monoxide and stabilizes oxygen binding C. Is primarily responsible for hemoglobin oxygen binding's pH sensitivity D. Is anti-aromatic E. Is soooo lazy. It just sits there and does nothing

B. Reduces affinity for carbon monoxide and stabilizes oxygen binding

Deprenyl is a monoamine oxidase inhibitor (MAOI) that contains no reactive groups except an anime and an alkyne. The compound selectively alkylates MAO when the enzyme tries to oxidize the inhibitor. The mode of inhibition is: A. Noncompetitive B. Suicide C. Competitive D. Uncompetitive

B. Suicide

A mutant enzyme binds a substrate 100-fold more tightly than the native enzyme. What is the effect of this mutation on the rate of reaction (catalysis) if the binding of the transition state is unaffected? A. The rate will be unaffected B. The rate is much lower for the mutant than for the native enzyme C. The rate will increase exactly 100-fold D. This is nonsense, enzymes don't bind substrates E. The rate is much higher for the mutant than for the native enzyme (but not exactly 100-fold higher)

B. The rate is much lower for the mutant than for the native enzyme

Which amino acid has a phenol in it's side chain? A. Asparagine B. Tyrosine C. Tryptophan D. Isoleucine E. Histidine

B. Tyrosine

Mutagenesis of chymotrypsin shows that: A. Only two of the three residues of the catalytic triad contribute to catalysis B. All three residues of the catalytic triad are required to get any catalysis C. All three residues of the catalytic triage contribute to catalysis D. Only the histidine contributes to catalysis E. Only the nucleophilic serine contributes to catalysis

C. All three residues of the catalytic triage contribute to catalysis

Which of the following is not a common mechanism regulating enzyme activity? A. Isozymes B. Covalent modification C. Alteration of reaction equilibrium constants D. Zymogens E. Allosterism

C. Alteration of reaction equilibrium constants

Antibodies to transition state analogs: A. Can completely stop reactions from happening B. Are great enzyme inhibitors C. Catalyze chemical reactions D. Are the basis of most ELISA tests E. Make you immune to organic chemistry

C. Catalyze chemical reactions

You homogenize a batch of liver cells and carry out differential centrifugation, at first 500 g for 20 minutes, then the supernatant is centrifuged again at 10,000 G for 20 minutes, then the supernatant is spun at 100,000 G for one hour. The pellet from this step contains what are called 'microsomes', which are: A. The genetic material from the cells B. The soluble cytosolic proteins C. Fragments of endoplasmic reticulum membrane D. Intact nuclei E. Intact mitochondria

C. Fragments of endoplasmic reticulum membrane

Which amino acid has an imidazole ring in it's side chain? A. Isoleucine B. Tryptophan C. Histidine D. Tyrosine E. Asparagine

C. Histidine

Which of the following terms describes the side chain of valine? A. Uncharged, polar B. Acidic C. Nonpolar D. Charged, polar E. Basic

C. Nonpolar

When a disulfide linkages form, the compound containing this new linkage has been_______. A. Dehydrated B. Reduced C. Oxidized D. Hydrolyzed E. Electrolyzed

C. Oxidized

The advantage of affinity chromatography is: A. Protein are separated in the denatured form, so shape isn't a factor B. The mitochondrial proteins are selectively purified from all the proteins in the cell C. That it can be very highly specific D. Molecules are separated based on isoelectric point E. That the media is cheap and widely available

C. That it can be very highly specific

If oxygen leaves hemoglobin and takes an electron with it, oxidizing the iron(II) to iron (III): A. The oxygen becomes water B. The oxygen becomes hydrogen peroxide C. The oxygen becomes superoxide D. This can't happen, oxygen can't gain or lose electrons E. This can't happen, the oxidation state of iron and hemoglobin isn't iron (II)

C. The oxygen becomes superoxide

In the biochemical standard state: A. Gases are all considered to be at 10 atm B. Delta G is always negative for any reaction equilibrium C. The proton concentration is 1X 10-7 M D. The proton concentration is 7 M E. The concentration of your liquids is 10 M

C. The proton concentration is 1X 10-7 M

Ethyleneimime reacts with cysteine side chains in proteins to form S-amnioethyl derivatives. The peptide bonds on the carboxyl side of these modified cysteine residues are susceptible to hydrolysis by trypsin. Why? A. They resemble methionine B. They become aromatic C. They look like lysine D. They are now negatively charged E. The cysteines can no longer form disulfides

C. They look like lysine

In the MWC model of allosterism, A. Kinases phosphorylate T states to make them R states B. A strict order of binding is observed, with the T-state always a current immediately after the R-state in the reactions mechanism C. and equilibrium exist between a more active R - state and a less active T - state D. A post translational modification of an R-state stoichiometrically provides a T-state E. Two different polypeptide chains are expressed, one called R-state and the other called T-state

C. and equilibrium exist between a more active R - state and a less active T - state

In the induced fit model of enzyme action, the enzyme active site: A. Uses an inhibitor to adjust its shape for the substrate B. Stays the same shape while causing a change in the shape of the substrate C. Uses a cofactor to change the shape of the substrate D. Adjusts shape to adapt to the shape of the substrate E. Stays the same shape during substrate binding

D. Adjusts shape to adapt to the shape of the substrate

One benefit of a cascade of zymogen activation (like in the blood clotting cascade) is: A. Energy isn't wasted synthesizing proteins before they are needed B. The response is slow, lasting months C. The process is completely reversible D. Amplification E. You get to come up with cool names like 'clotting factor IX' and 'clotting factor VII'

D. Amplification

The free amino acid glycine at neutral at pH is: A. Fully protonated B. An acid C. Neither acid nor bass D. An acid and a base E. A base

D. An acid and a base

Kinases typically phosphorylate: A. Tyrosine B. Serine C. Threonine D. Any of the above E. None of the above

D. Any of the above

The rate of carbonic anhydrase reaction would be limited by proton diffusion and the pKa of the active site nucleophile. The reaction really goes much faster than this limit usually, however, because: A. Diffusion is always irrelevant in enzyme kinetics B. Of allosterism C. The enzyme greatly speed the diffusion of proteins D. Buffer participates in the reaction E. Magic. Sheer magic.

D. Buffer participates in the reaction

Dicyclohexylcarbodiimide is a reagent for: A. Cleaving peptide chains after methionine residues B. Marking the N terminal amino acid of a peptide C. Reducing disulfide bonds D. Coupling carboxylic acids to amine to form amides E. Oxidizing disulfide bonds two pairs of cysteic acids

D. Coupling carboxylic acids to amine to form amides

Central dogma of molecular biology is that genetic information primarily flows from: A. RNA to protein to DNA B. Protein to RNA to DNA C. RNA to DNA to protein D. DNA to RNA to protein E. Protein to DNA to RNA

D. DNA to RNA to protein

Denaturation of a protein: A. Can only occur in a protein with quaternary structure B. Change is the primary structure of a protein C. Is always irreversible D. Disrupts the secondary, tertiary, or quaternary structure of a protein E. Hydrolyzes peptide bonds

D. Disrupts the secondary, tertiary, or quaternary structure of a protein

CTP slows down ATCase. This is an example of: A. Feed forward activation B. Competitive inhibition C. Suicide inhibition D. Feedback inhibition E. Catalytic antibody-ism

D. Feedback inhibition

You run an HPLC analysis of the amino acids present in small peptide and find of the amino acids Glu, Ala, Gly, Phe, and Lys are present. You also see a peek for ammonia. Which of the following amino acids must have been present in the peptide? A. Trp B. Asn C. Arg D. Gln E. His

D. Gln

You are trying to explain to Dr. Primm how chymotrypsin-catalyzed protein hydrolysis works. He says the active site serine acts as an acid in the reaction. In reality, it acts as a(n): A. Lowry base B. Electrophile C. Bronsted base D. Nucleophile E. Reducing agent

D. Nucleophile

Dothiothreitol (DTT) and beta-mercaptoethanol are both used to: A. Denature proteins by interfering with hydrogen bonds B. Reduce thiols C. Oxidize disulfide bonds D. Reduce disulfide bonds E. Make lab smell really good (ahhhhhh, rotten eggs)

D. Reduce disulfide bonds

Enzymes accelerate reactions by: A. Stabilizing substrates, lowering activation energy B. stabilizing products, lowering activation energy C. Stabilizing products, raising activation energy D. Stabilizing transition state, lowering activation energy E. Stabilizing substrates, raising activation energy

D. Stabilizing transition state, lowering activation energy

In Michaelis-Menten kinetics, if you double the amount of substrate, without changing the enzyme concentration, A. There will be no change in rate B. You will get double the rate C. You will get half the rate D. The change in rate will depend on the substrate concentration you are using E. You will get the same rate

D. The change in rate will depend on the substrate concentration you are using

How can you tell that protein purification is going well by SDS-PAGE? A. The size of the proteins band goes up B. The protein's band gets lighter the more pure the sample gets C. The size of the proteins band goes down D. The sample gives few were bands, hopefully a single band in the end E. You can't tell by SDS-PAGE

D. The sample gives few were bands, hopefully a single band in the end

Peptide bonds in proteins are typically found in the______ confirmation. A. Gauche B. S-cis C. Cis D. Trans E. Z

D. Trans

On a double reciprocal, or Lineweaver-Burke, plot: A. you plot v versus 1/s B. the slope is Vmax and the x-intercept is -1/Km C. you get a hyperbola that approaches Vmax D. the y-intercept is 1/Vmax and the x-intercept is -1/Km E. he x-intercept is 1/Vmax and the y-intercept is -1/Km

D. the y-intercept is 1/Vmax and the x-intercept is -1/Km

The pKa of the side chain leucine is: A. 8 B. 10 C. 3 D. 13 E. (There is none, at least not less than 30)

E. (There is none, at least not less than 30)

A zymogen is: A. A protein that gets phosphorylated to activate it B. A protein that adds phosphate groups to Ser, Thr, and Tyr C. A protein that gets phosphorylated to inactivate it D. An enzyme that catalyzes the carboxylation of glutamate E. A proteins synthesized as an inactive precursor

E. A proteins synthesized as an inactive precursor

Common covalent modifications of protein activity include: A. Ubiquitination B. Gamma-carboxylation C. Sulfation D. Phosphorylation E. All of the above

E. All of the above

Isozymes can differ in: A. Vmax B. Allosteric regulation C. Distribution among tissues D. Substrate affinity E. All of the above

E. All of the above

In ATCase, there are two different kinds of subunits,____ and_____. A. Carbamoyl phosphate binding and aspartate binding B. Kinase and phosphatase C. Fetal and adult D. High affinity and low affinity E. Catalytic and regulatory

E. Catalytic and regulatory

Unlike hemoglobin, myoglobin: A. Lacks cooperativity, but is also a tetramer B. Is a monomer and lacks cooperativity C. Doesn't bind oxygen D. Lacks heme E. Is a monomer and demonstrates more highly cooperative oxygen binding

E. Is a monomer and demonstrates more highly cooperative oxygen binding

Water molecules adjacent to oil droplets are _____ compared to water molecules in bulk water. A. Disordered B. Capable of making more hydrogen bonds C. More positively charged D. More negatively charged E. Ordered

E. Ordered

In an alpha helix, the amino acid side chains: A. Stick to the interior of the helix B. Must form disulfide with a residue a few amino acids down the chain C. Hydrogen bond to each other to hold the helix together D. Cannot be very large or the helix cannot form E. Stick out from the surface of the helix

E. Stick out from the surface of the helix

Which of the following amino acids has a side chain that would be neutral at pH 12? A. Cys B. Lys C. Asp D. Glu E. Tyr

E. Tyr

In Michaelis-Menten kinetics, if you double the amount of enzyme, without changing the substrate concentration, A. The change in rate will depend on the substrate concentration you are using B. You will get half the rate C. There will be no change in rate D. You will get the same rate E. You will double the rate

E. You will double the rate

In the derivation of the Michaleis-Menten Equation, we make the assumption of steady state. This assumption is: A. d[S]/dt=0 ([S] doesn't change) B. [P]<<<[S]([P] is much smaller than [S]) C. [ES] = all the enzyme we put into the reaction D. that no product is formed E. d[Es]/dt = 0 ([ES] doesn't change

E. d[Es]/dt = 0 ([ES] doesn't change

In the alpha helix, the i-th amino acid's carbonyl will hydrogen bond to the ______ amino acid's amine N-H. A. i + 1 B. i + 3 C. i + 5 D. i + 2 E. i + 4

E. i + 4

A lack of what causes scurvy?

Hydroxyproline

You discover a new amino acid found in proteins that has a side chain that is different than the standard 20. If the PK of the side chain of this amino acid is determined to be 8.9, is the side chain primarily protonated or deprotonated at physiological pH?

Protonated

One of the benefits of allosterism in hemoglobin, which results in sigmoid oxygen binding curve, is that: a. there is maximal change in oxygen binding between the lung oxygen pressure and the typical (or active) tissue oxygen pressure b. oxygen binds more strongly to hemoglobin at all oxygen pressures than if it wasn't allosteric c. it allows hemoglobin to function as a monomer., saving the energy cost of maintaining and expressing multiple genes d. hemoglobin is able to bind to oxygen more tightly than myoglobin at tissue oxygen concentrations, saving oxygen for other tissues e. there is no advantage, it is an artifact of evolution

a. there is maximal change in oxygen binding between the lung oxygen pressure and the typical (or active) tissue oxygen pressure

When 2,3-bisphosphoglycerate (2.3-BPG) is bound to hemoglobin, a. the oxygen binding site is completely blocked b. hemoglobin's affinity got oxygen is decreased c. hemoglobin shifts mostly to R-state d. oxygen binds more tightly due to BPG providing additional interactions in the active site e. actually, 2,3-BPG does not bind to hemoglobin

b. hemoglobin's affinity got oxygen is decreased

The 'catalytic efficiency' is defined as: a. Km/kcat b. kcat/Km c. Km/Vmax d. kcat/Vmax e. Vmax/Km

b. kcat/Km

In MALDI-TOF analysis of an unknown peptide, the protonated peptide comes at m/z 4330. A mystery peak occurs at m/z 2116. This peak is most likely: a. the protein losing its C-terminal amino acid b. a protonate dimer of the protein c. double protonated protein d. an aggregate of protein molecules resulting from oxidation of surface cysteine resudues e. the protein losing its N-terminal amino acid

c. double protonated protein

In Michaelis-menten kinetics, Vmax is: a. the rate of reaction at infinitely low substrate concentration b. the rate of reaction at infinitely high enzyme concentration c. the rate of reaction at infinitely high substrate concentration d. the rate of reaction when [E] >>> [S] e. the rate of reaction at an infinitely low enzyme concentration

c. the rate of reaction at infinitely high substrate concentration

Antigens are: A. a special type of antibody B. always denatured protein C. what antibodies bind to D. peptide hydrolyzing enzymes E. cells that bind to antibodies

c. what antibodies bind to

Trypsin cleaves polypeptide chains: a. after hydrophobic amnion side chains b. completely into free amino acids c. after methionine residues d. after positive amino acid side chains e. starting with the C-terminal residue

d. after positive amino acid side chains

Antibodies can be used to stain which part of cells? a. the cytoskeleton b. the nuclear membrane c. 'nuclear' hormone receptors d. the endoplasmic reticulum e. all of the above and much more

e. all of the above and much more

The Henderson-Hasselbalch equation states that:

pH = pKa + log ([A-]/[HA])