Week 4 biochem CFP review

A coenzyme that is permanently bound to an enzyme and remains unchanged after a reaction is called? A. Prosthetic group B. Cofactor C. Holoenzyme D. Co-Substrate E. Apoenzyme

A

Enzymes influence chemical reactions in living systems by: A. Decreasing the energy needed for the formation of product. B. Providing the substrate required for the reaction to occur. C. Increasing the affinity of the substrate at high substrate concentration. D. Lowering the rate at which reactions occur.

A

For Non Competitive inhibitors: A. On a Lineweaver-Burk plot, their graph will show two lines with the same X intercept B. They decrease both Km and Vmax C. They increase the Km of the enzyme D. They bind to the enzyme active site E. On a Lineweaver-Burk plot, their graph will show two lines with the same Y intercept

A

In Hemoglobin, CO binds to: A. The same binding site as O2 B. Proximal Histidine C. The positive charge cavity formed by the beta chains D. The terminal -NH2 of the α and β chains E. Distal Histidine

A

In Oxy hemoglobin (Hb),the Fe(II) is coordinated to: A. Four nitrogens, proximal His residue and an O2 molecule B. Four nitrogens and proximal His C. Four nitrogens and distal His D. Four nitrogens and two His residues E. Four nitrogens and an O2 molecule

A

In the Tripeptide, Gln-Gly-Glu, the amino acid with the free amino end is: A. Glutamine B. Glutamate C. Glycine D. None of the above

A

Induction can be described as: A. Increasing the amount of Enzymes B. Increasing the amount of Phosphorylation C. Increasing the amount of Substrate D. Increasing the amount of Products E. Increasing the amount of Allosteric effectors

A

One of the factors that regulate the activity of an enzyme is substrate availability. When can an enzyme be effectively regulated by the substrate concentration? A. At low substrate concentration B. At any substrate concentration C. When the enzyme is saturated with the substrate D. When the enzyme concentration is high E. When the substrate concentration is higher than Km

A

Statin drugs are similar in structure to one of the substrates in Cholesterol synthesis. Statin is considered to be a: A. Competitive inhibitor B. Noncompetitive inhibitor C. Irreversible inhibitor D. Uncompetitive inhibitor

A

The graph below represents: A. A Competitive inhibitor that does not change the Vmax of the enzyme B. A Homotropic Allosteric effector that changes the Km of the enzyme C. A Heterotropic Allosteric effector that changes the Vmax of the enzyme D. A Noncompetitive Inhibitor that does not change the Km for the enzyme E. An Uncompetitive inhibitor that changes both Km and Vmax

A

The tertiary structure of a protein forms from the folding of secondary structures, and is often the functional form of a protein. Which one of the following describes this level of protein structure? A. Contains only one polypeptide chain B. R groups with opposing charges form covalent bond to stabilize this structure C. Only non covalent interaction stabilizes this structure D. Secondary structure determines the protein function E. Denaturation is the unfolding of the tertiary structure and resuming the secondary structure

A

What conclusion can you draw from the Mechaelis-Menten plot for enzyme A and B below? A.A non-competitive inhibitor is acting on the enzyme B.A will reach its Km at lower substrate concentrations C.B would have higher affinity for the substrate D. A has a higher Km than B E.A would reach Vmax at higher substrate concentration

A

Which of the following is True regarding amino acids? A. D and L isomers are considered mirror images B. Only one amino acid out of all the 20 has a chiral center C. Most naturally occurring amino acids exist in the D configuration D. D and L isomers are determined based on the position of the carboxyl group E. Only some of the 20 amino acids can have L and D isomers

A

Which of the following is not a characteristic of Quaternary structure? A. Stabilized by a mixture of non-covalent and covalent bonds B. Allosteric protein C. Hemoglobin is an example D. Multisubunit protein E. Held together by a number of non-covalent interactions

A

Which one of the following is an example of Tertiary Structure? A. Domains B. Multimeric Protein C. Polyalanine D. Alpha helix E. Beta pleated sheets

A

Which one of the following is true about the T state of Hb? A. It is the form of Hb when it reaches the Tissues B. It is when Hb has high affinity for O2 C. This forms when Hb curve shifts to the left D. It is when some weak bonds between αβ dimers will be broken E. It is when the Heme is Planar in shape

A

Which one of the following will be true for the molecule 2,3 BPG A. It binds to the positively charged cavity formed by the beta chains B. It binds to the active site of the enzyme C. It binds to Hb and stabilizes the relaxed conformation D. Four molecules of 2,3 BPG bind to four heme E. It shifts the O2 dissociation curve to the left

A

You have obtained the following data for enzyme activity measured in the presence of an inhibitor. Identify the type of inhibition. A. Noncompetitive B. Uncompetitive C. Irreversible D. Competitive

A

A competitive inhibitor will: A. Decrease apparent Vmax as well as decrease Km B. Increase apparent Km without affecting Vmax C. Increase apparent Km as well as increase Vmax D. Decrease apparent Vmax without affecting Km E. Decrease apparent Km without affecting Vmax

B

A metal ion that is needed for the function of a specific enzyme may be referred to as: A. Apoenzyme B. Cofactor C. Coenzyme D. Holoenzyme E. Organic molecule

B

At high substrate concentration the Enzyme? A. Velocity will be dependent on substrate concentration B. Velocity will not depend upon substrate concentration C. Velocity will be at about ½ Vmax D. Turnover number will be relatively low E. Has high affinity for the substrate

B

Reductases are enzymes that require electrons to reduce the substrate that they work on. Usually they use NADH as a coenzyme. In cases of deficiency, the reductases enzymes without its coenzyme will be called: A. Holoenzyme B. Apoenzyme C. Cofactor D. Prosthetic Group E. Coenzyme

B

Scientists discover a new enzyme and begin to study its activity. They realize that to function the enzyme requires a non protein, non metallic molecule, that dissociates over the course of the reaction. This non protein component can be described as a: A. Cofactor B. Co-substrate C. Holoenzyme D. Substrate E. Prosthetic group

B

The effects of low blood pH and high CO2 on Hb O2 binding: A. They cause Hb molecule to increase its affinity for oxygen B. Unload oxygen to the Tissues C. Shift the Hb‑O2 binding isotherm curve to the left D. Cause most Hb molecules to assume a "relaxed" Conformation E. Are Opposites to one another

B

When Hb is in the relax form which one is True? A. Shift of the sigmoidal curve to the right will be seen B. Weak interactions between dimers will be broken C. The affinity for O2 will be low D. This form is promoted/stabilized by the low pH of the tissues E. The heme will be domed

B

Which of the following conditions causes Hb affinity for oxygen to increase: A. An acidosis condition is established B. A molecule of Oxygen binds to one of the Heme groups C. Increase in Carbon Dioxide concentration D. Increase in Hydrogen ion concentration E. Increase in 2,3-BPG concentration

B

Which of the following has the lowest P50? A. Hb-A + 2,3-BPG B. Mb C. Hb-A at pH 7.2 D. Hb-A at pH 7.6

B

Which one of the following Peptide chains can form an Alpha helix structure? A. PolyTryptophan B. PolyAlanine C. PolyProline D. PolyGlutamate E. PolyArginine

B

Which one of the following statements describes the status of a person with a pulmonary obstruction (obstructed airflow): A. Low concentration of H+ B. Low plasma pH C. Stable pH near physiological pH D. High HCO3- E. High plasma pH

B

You use an acid hydrolysis to determine the amino acid composition of a protein. Using this information, which of the following would you most likely be able to figure out about the protein: A. The amino acids sequence B. How many disulfide bonds are possible C. The type secondary structures it contained D. Its specific function in the body E. How it will fold in its tertiary structure

B

hich one of the following is TRUE about Myoglobin? A. Myoglobin has a sigmoidal dissociation curve B. Myglobin consists predominately of alpha helices C. Myoglobin decreases its affinity for Oxygen when the pH of the environment falls from 7.5 to 7.2 D. Myoglobin binds four oxygen molecules when it is fully saturated E. Myoglobin has a low affinity for Oxygen.

B

Amoxicillin is a weak acid with pKa equal to 2.9. If you know that stomach pH =1.9, which one of the following will be a True statement: A. The drug will not be absorbed. B. The ionized form is much larger than the neutral form C. The neutral species of the drug is 10 folds larger. D. The ionized form is equal to the neutral form E. The neutral species of the drug is 10 folds smaller.

C

As blood (from the lungs) travels through the peripheral tissues, hemoglobin affinity for O2 __?__ and the pH __?__. A. Increases ... decreases B. Increases ... increases C. Decreases ... decreases D. Decreases ... increases

C

Scientist are observing a skin sample and find a protein with the following properties: It contains amino acids with small side chains regularly throughout the structure. It consisted of 3 helical structures tightly wound together. Which of the following is most likely TRUE? A. It would be the main component in structures like nails and hair. B. This protein contains alpha helixes mostly but some beta-sheets as well. C. It would also be observed in the tendons and bone. D. It would cause a TSE disease when it forms a very stable protein. E. It has high water solubility.

C

Which one of the following is TRUE for Hemoglobin, a complex quaternary structure? A. The Hemoglobin tetramer binds 4 molecules of 2,3 BisPG B. In the deoxygenated form of Hb some non-covalent interactions between the αβ dimers are broken C. Hb affinity for oxygen increases as the percentage O2 saturation increases D. Hemoglobin has a lower affinity for Oxygen at high pH values E. Low pH stabilizes Hb in its R state.

C

Which statement is TRUE about covalent modification? A. It is irreversible B. It usually uses the same enzyme for activation or inhibition C. It is quicker than regulation by induction D. The amino acids Serine and Proline are known to participate in covalent modification E. Activation involves the synthesis of more enzymes

C

Which statement regarding hemoglobin and myoglobin is FALSE? A. O2 binding curve of Mb is Hyperbolic B. On a graph, the O2 saturation curve of Mb is to the left of the Hb saturation curve C. When pO2 is low, O2 affinity of Hb is high D. When bonded to Oxygen, heme is planar

C

n deoxy hemoglobin (Hb), the Fe (II) is bonded to: A. Four Nitrogens, an O2 and the two His residues B. Four Nitrogens only C. Four Nitrogens and the proximal His D. Four Nitrogens and the distal Histidine. E. Four Nitrogens and an O2 molecule.

C

stored blood becomes depleted from 2,3BPG. What effect does this have on the hemoglobin-oxygen dissociation curve? A. Does not change the dissociation curve B. Shifts the curve to the left. so that the hemoglobin has a decreased oxygen affinity C. Shifts the curve to the left, so that the hemoglobin has an increased oxygen affinity D. Shifts the curve to the right, so that the hemoglobin has an increase oxygen affinity E. Shifts the curve to the right, so that the hemoglobin has a decrease oxygen affinity

C

Which of the following statements about enzyme regulation are TRUE? (Select all that apply) A. Enzyme activity can be altered by temperature, pH but not by the addition of phosphate groups. B. Homotropic effectors will most likely have a negative effect on substrate binding C. Induction is synthesis D. Truncation of an enzyme can affect its activity

C D

Which of the following about Competitive Inhibitors are TRUE? (Select all that apply) A. They bind to the ES complex B. They bind to another site on the enzyme C. They form a Lineweaver-Burk plot that has a common intercept on the Y axis D. They decrease Vmax of the enzyme E. They increase the Km of the enzyme

C E

A new inhibitor was discovered by scientist. After extensive research they realized that the inhibitor can bind to either the E or ES complex at a site that is not the enzymes catalytic site. This new inhibitor is most likely a : A. Uncompetitive inhibitor B. Irreversible inhibitor C. Competitive inhibitor D. Noncompetitive inhibitor

D

Blood from a patient who has been vomiting uncontrollably for several hours, is likely to exhibit an oxygen binding curver that is: A. Shifted to the left due to acidotic conditions B. Shifted to the right due to acidotic conditions C. Shifted to the right due to alkalotic conditions D. Shifted to the left due to alkalotic conditions

D

Enzyme A is a zymogen that must be truncated in order to become active. Enzyme B is inactivated by a phosphatase. Which of the following is true: A. Only Enzyme A is being regulated by covalent modification B. Enzyme B is being regulated by induction C. Enzyme A is being regulated by an allosteric effector D. Enzyme B can be activated by a kinase

D

R-groups in an α-helix: A. Have to be close together to stabilize the helix B. Are arranged similarly to those on the anti-parallel β-sheets C. Extend inward from the central axis D. Extend outward from the central axis E. Are hydrogen bonded to the next R group in the chain

D

Scientists observing protein synthesis notice a protein that kept unfolded peptide chain separate and protected against unwanted side-chain interactions. They also noticed that the synthesis of this protein increased in response to high temperatures and other conditions that would cause denaturation within the cell. Which of the following is most likely the protein they were observing? A. Ribosomal Proteins B. Hemoglobin C. PrPSc D. Chaperones E. Myoglobin

D

This form of regulation results in increased synthesis of an enzyme. A. Proteolytic cleavage B. Covalent modification C. Allosteric Regulation D. Induction E. Repression

D

When we denature proteins, they still retain their ____________ structure. _____________ are enzymes that help to degrade proteins because they are able to break _________ bonds. A. Primary....Oxidoreductases.....peptide B. Primary......Kinases......hydrogen C. Secondary....Proteases....peptide D. Primary......Proteases.......peptide E. Secondary....Ligases.....ionic

D

Which of the following characteristics is NOT shared by both hemoglobin and myoglobin? A. A proximal Histidine attached to the iron center B. Binds O2 reversibly C. Possesses a heme prosthetic group D. Their affinity for Oxygen at low oxygen concentration E. A distal Histidine stabilizes oxygen binding

D

Which of the following is NOT True about globular proteins? A. They are stabilized by interactions between R groups B. They have non polar amino acids on their interior C. They can have heme prosthetic groups and be used for O2 transport. D. They are stabilized by a variety of inter molecular bonds including disulfide bonds E. They tend to be made of a variety of secondary structures

D

Which of the following is TRUE about the Primary Structure of Protein? A. Edman's reagent is used once to identify the amino acid composition B. It's described as the local arrangement of adjacent amino acids in space to form a 3D structure C. It is usually stabilized by intermolecular disulfide bonds D. The primary sequence of an amino acid can be determined from the DNA sequence E. Non covalent bonds are the primary stabilizing forces

D

Which of the following statements about the Michaelis-Menten constant (Km) is correct? A. Km value decreases in competitive inhibition B. Km defines the concentration of a substrate needed for a biochemical reaction to occur C. Km is equal to ½ Vmax D. Km is the substrate concentration required to attain ½ maximal velocity E. Km Value is proportional to enzyme affinity to the substrate

D

Which of the following statements describes a non-competitive inhibitor? A. They bind covalently to the enzyme B. Binding occurs at the same site as substrate C. Their binding will result in a Michaelis-Menten plot showing an increase in Km D. Binding occurs at site other than the catalytic site E. Most are heavy metals

D

Which of the following statements is TRUE? A. The lock and key model is a more accurate description of enzyme-substrate binding than the induced-fit model. B. At low substrate concentration, the speed of the reaction will not be affected by increasing the amount of substrate. C. Enzymes lower the overall free energy and the activation energy of the reaction. D. At high substrate concentration, all of the enzymes will be saturated and the reaction rate cannot be increased by increasing the substrate concentration. E. All enzymes will have the same maximal temperature range and pH.

D

Which of the following will disrupt the stability of a secondary structure of a protein? A. Substitute Cystein with Serine. B. Substitute Serine with Tyrosine. C. Substitute Serine with Threonine D. Substitute Tyrosine with Proline E. Substitute Methionine with Valine

D

Which of the following would NOT occur as a result of a build up of CO2? A. 2,3 BPG binding to Hemoglobin B. Increase in proton concentration C. Acidosis D. Alkalosis E. Acidemia

D

Which of the following would result in acidosis: A. Increased flow of blood and oxygen throughout the body B. Decrease in blood proton concentration C. Persistent vomiting D. Retention of CO2 during asthmatic episodes E. Loss of CO2 due to increased exhalation

D

Which one of the following Polypeptides readily forms an alpha helix at pH = 7? A. Polyproline B. Polytryptophan C. Polyglutamate D. Polyalanine E. Polyarginine

D

Which one of the following is TRUE about Edman degradation system of sequencing polypeptides? A. It uses an electric field to separates charged amino acids. B. It will work on any size polypeptide chain C. Individual amino acids are separated by Cation/Anion exchange. D. The N-terminal will be labeled and cleaved and identified in each successive cycle E. It hydrolyzes the polypeptide to its constituent amino acids

D

Which one of the following statements concerning the peptide shown belowis correct: Gly-Cys-Glu-Ser-Asp-Arg-Met A. The peptide contains Asparagine B. The peptide contains an amino acid with a ring in its side chain. C. The peptide contains Glutamine. D. The peptide is able to form ionic bonds E. The peptide is able to form an intramolecular disulfide bond.

D

Which one of the following statements is TRUE? A. Phenylalanine would most likely be found on the interior of a membrane protein B. Gly and Pro help to stabilize the secondary structure of proteins C. Methionine would be found on the surface of globular proteins D. Tyrosine residues facilitate the phosphorylation of proteins E. Proline can form hydrogen bonds during protein folding

D

Which one of the following statements is True about the alpha helix of the polypeptide shown below: Leu - Ala - His -Asp - Leu- Glu - Lys- Val - Thr - Arg - Cys -- Tyr A. It contains Tyrosine as its free amino end B. It would most likely be found on the interior of a globular protein C. It can form a disulfide bridge D. It consists of approximately 3 turns E. It is not able to form any Ionic bonds

D

Which one of the following statements is True: A. Allosteric effectors can change the affinity of Mb O2 binding B. Hb has high affinity for O2 at low O2 concentration. C. In the deoxygenated form of Hb the heme will be planar D. Binding of O2 disrupts some bonding between αβ dimers E. αβ dimers joined by covalent bonds

D

Which one of the following statements is correct concerning Enzyme inhibition? A. In noncompetitive inhibition Vmax remains unchanged B. A competitive inhibitor binds to the ES complex C. The effect of an Uncompetitive inhibitors can be represented on a Lineweaver- Burk Plot as a set of lines having a common intercept on the X axis (same Km value). D. In competitive inhibition, an increase in Km occurs as the inhibitor binds to the same active site as the normal substrate E. Noncompetitive inhibitors decrease the Km for the substrate.

D

Which one of the following will cause a left shift in the oxygen dissociation curve for hemoglobin? A. Low pH B. High H+ conc. C. High Lactate D. High O2 E. 2-3 BPG

D

While studying a new enzyme scientists realize that its substrate acts as a positive effector. Its effect was similar to the cooperative oxygen binding seen in Hemoglobin. The type of regulation being exhibited was most likely: A. Proteolytic cleavage B. Covalent Modification C. Induction D. Allosteric E. Repression

D

Which of the following peptide chains would be found in the center of a globular protein: A. Alanine - Valine - Leucine - Lysine - Threonine B. Alanine - Aspargine - Glutamine - Tyrosine C. Leucine - Lysine - Isoleucine - Tryptophan D. Alanine - Phenylalanine - Valine - Leucine E. Valine - Serine - Leucine - Phenylalanine

D all the non polar ones

A group of Biochemistry students are asked to run a series of tests in a lab to classify a given enzyme. The students realize that their given enzyme uses water to help covalently modify other enzymes, by removing a phosphate group. What type of enzyme were the students most likely given? A. Kinase B. Oxidoreductase C. Ligase D. Lyase E. Phosphatase

E

A person exercising anaerobically, has increased delivery of O2 to their tissues because: A. The increase in Lactate produced by metabolism forces Hb into its Taut conformation B. 2,3 BisPG produced by metabolism binds to Hemoglobin and decreases its affinity for O2 C. Hemoglobin dissociation curve will shift to the left promoting O2 release D. a),b), and c) are correct E. Both a) and b) are correct

E

An organic compound that is needed for a specific enzyme to function is called? A. A holoenzyme B. An Apoprotein C. A Cofactor D. An apoenzyme E. A coenzyme

E

Biotin is needed for the enzyme Pyruvate Carboxylase to function. Biotin is a vitamin we can refer to as a type of: A. Holoenzyme B. Apoenzyme C. Catalyst D. Cofactor E. Coenzyme

E

In the Graph below what is shown as the line moves in the direction of the arrow? A. Effect of a Competitive inhibitor B. Increase in the concentration of the substrate C. Effect of an Uncompetitive inhibitor D. Decrease in the concentration of the inhibitor E. Effect of a Noncompetitive inhibitor

E

Lactate Dehydrogenase is an enzyme that can convert Pyruvate to Lactate. To do so it requires NADH which it oxidizes to NAD+ in the reaction. Lactate Dehydrogenase could classified as a .................... and NADH/NAD+ would be a ........................... A. Transferase .................Cofactor B. Hydrolase ...............Prosthetic group C. Ligase............Cofactor D. Lyase..............Prosthetic group E. Oxidoreductase ............ Co-substrate

E

The affinity of two different enzymes for their substrates can be compared by : A. Their ability to form products B. Their activation energy C. Their optimum pH D. The size of their active site E. Their Km value

E

Which of the following characteristics is SHARED by both Hemoglobin and Myoglobin? A. A multisubunit protein. B. Location and Function C. Number of Hemes D. Affinity for O2 at low O2 concentration E. Heme binding pocket with histidine residues and Fe 2+

E

Which of the following is CORRECT about Hemoglobin? A. The Hb O2 binding curve is hyperbolic B. Carbon monoxide and oxygen bind to distinct sites on Hb molecule C. Hb affinity for oxygen increases during anaerobic exercise D. Hb affinity for oxygen increases at high altitudes E. Hb affinity for oxygen decreases with the addition of 2,3 BPG

E

Which one of the following conditions will stabilize Hemoglobin in its OxyHb (high affinity for O2) A. 2,3BPG B. High Lactic acid C. High Altitude D. High CO2 E. High pH

E

Which one of the following is TRUE about Allosteric regulation? A. The effectors bind at the same site as the substrate B. Causes a hyperbolic curve C. The effector is always the same the substrate D. Involves activating enzymes by removing part of them E. Can have either positive or negative effectors

E

Which one of the following statements will be True about the following polypeptide chain Gly-Glu-Gln-Ser-Asp-Lys-Arg-Pro-Cys-Met-Cys A. It is found mainly on the interior of globular proteins B. It contains the amino acid Asparagine C. It contains an aromatic amino acid D. It is able to form an alpha helix (without disruption) E. It is able to form an intramolecular disulfide bridge

E

Which amino acid pair would most likely be found on the surface of membrane protein? A. Threonine - Tyrosine B. Proline - Serine C. Serine - Valine D. Tyrosine - Tryptophan E. Phenylalanine - Alanine

E bc they are both non polar

Which one of the following conditions will stabilize Hemoglobin in its OxyHb form. A. High CO2 B. High altitude C. High lactate D. High H+ E. High 2,3BPG F. High pH

F

A complete and catalytically active enzyme together with its bound vitamin or metal ions is called? A. Prosthetic group B. Organic Molecule C. Holoenzyme D. Apoenzyme E. Coenzyme

c

Phosphorylation is a common means of regulating protein activity. Which of the following amino acids are typically phosphorylated in proteins regulated by kinases?

tyrosine and threonine