Biochem Final

Front 1

Product feedback inhibition would be illustrated by metabolite VI most likely inhibiting which enzyme in the pathway? If enzyme F is allosterically inhibited by product VI, the structures of IV and VI should be _____________ .

Back 1

a) A; different b) B; different c) D; different d) F; different e) G; different f) A; similar g) B; similar h) D; similar i) F; similar j) G; similar

Hint 1

B

Front 2

If activity of enzyme D is regulated by phosphorylation, is it possible that enzyme D is also regulated by an allosteric regulator? Which of the following regulations is(are) reversible?

A. Allosteric regulation B. Covalent regulation C. Proteolytic activation

Back 2

a) No; A and B b) No; C c) Yes; A and B d) Yes; C

Hint 2

C

Front 3

3. Aspartate transcarbamoylase (ATCase) catalyzes the reaction: carbamoylphosphate + aspartate → carbamoylaspartate and phosphate. The charge of carbamoylaspartate is ________ . Its activity is allosterically regulated by CTP and ATP. ATCase has six catalytic subunits and six regulatory subunits. CTP is an allosteric inhibitor and also a possible ___________ inhibitor.

Back 3

a) -1; noncompetitive b) -1; uncompetitive c) -2; noncompetitive d) -2; uncompetitive

Hint 3

C

Front 4

Isozymes are enzymes with slightly different subunits in structure and catalytic function. Lactate dehydrogenase, an example of isozyme, has two different isoforms H and M. The tetramer, H4 expressed in heart, has the highest catalytic activity to convert _____________. One of the products is for the fuel of the citric acid cycle/TCA. An excess of the H type of lactate dehydrogenase in serum indicates a heart problem. In contrast, the tetramer, M4 expressed in muscle, has the highest catalytic activity to convert ____________ since one of the products is generated for continuing glycolysis

Back 4

a) lactate and NADH to pyruvate and NAD+; pyruvate and NAD+ to lactate and NADH b) pyruvate and NAD+ to lactate and NADH; lactate and NADH to pyruvate and NAD+ c) lactate and NAD+ to pyruvate and NADH; pyruvate and NADH to lactate and NAD+ d) pyruvate and NADH to lactate and NAD+; lactate and NAD+ to pyruvate and NADH

Hint 4

C

Front 5

As a consequence of Mutation A, which of the following hormone responses is most likely to be decreased? Enhanced cAMP cellular level will lead to the events of _____________ in the cells with mutation A compared to the activity of glycogen phosphorylase and synthase at their normal cAMP cellular level.

Back 5

a) glucagon; A and D b) glucagon; E and F c) insulin; A and D d) insulin; E and F

Hint 5

B

Front 6

As a consequence of Mutation B, which of the following hormone responses is most likely to be decreased? Enhanced cAMP cellular level will lead to the events of _____________ in the cells with mutation B compared to the activity of glycogen synthase and phosphorylase at their normal cAMP cellular level.

Back 6

a) glucagon; E and F b) glucagon; B and C c) insulin; E and F d) insulin; B and C

Hint 6

A

Front 7

Caffeine is a bitter, white crystalline xanthine alkaloid and a stimulant drug. Caffeine is a central nervous system and metabolic stimulant, and is used both recreationally and medically to reduce physical fatigue and to restore alertness when drowsiness occurs. It produces increased wakefulness, faster and clearer flow of thought, increased focus, and better general body coordination. Drinking a caffeinated beverage would inhibit activity of _____________. As a consequence, drinking a caffeinated beverage would _____________ cAMP signaling.

Back 7

a) Enzyme X; enhance b) Enzyme X; inhibit c) Enzyme Y; enhance d) Enzyme Y; inhibit

Hint 7

C

Front 8

In the Figure above, how many phosphodiester bond(s) in total is(are) recognized by nuclases? What the enzyme(s) catalyzes (catalyze) formation of phosphodiester bond?

Back 8

a) 1; Enzyme X b) 1; Enzyme X, Y and Z c) 4; Enzyme X d) 4; Enzyme X, Y and Z

Hint 8

A

Front 9

How many different active proteases are involved in intrinsic pathway based on the diagram above? How many different zymogens in extrinsic pathway based on the diagram above?

Back 9

a) 7; 3 b) 7; 4 c) 8; 3 d) 8; 4

Hint 9

A

Front 10

What is A in the diagram above? The A in the diagram catalyzes the crosslink reaction between glutamine of one fibrin monomer and ___________ in another fibrin monomer?

Back 10

a) transglutaminase; glutamate b) transglutaminase; lysine c) thrombin; glutamate d) thrombin; lysine

Hint 10

B

Front 11

Back 11

a) elastase; negatively b) elastase; positively c) thrombin; negatively d) thrombin; positively

Hint 11

C

Front 12

Back 12

a) two; A: Plasminogen; B: Tissue Plasminogen Activator; C: Plasmin b) four; A: Plasminogen; B: Tissue Plasminogen Activator; C: Plasmin c) two; A: Tissue Plasminogen Activator; B: Plasminogen; C: Plasmin d) four; A: Tissue Plasminogen Activator; B: Plasminogen; C: Plasmin

Hint 12

D

Front 13

Which of the following would be the best method to separate α-antitrypsin from Met  Lys mutation of α-antitrypsin? Alternatively, if you would like to purify α-antitrypsin from a cell by affinity chromatography, you will need ________

Back 13

a) Size-exclusion chromatography; elastase b) Size-exclusion chromatography; trypsin c) Ion-exchange chromatography; elastase d) Ion-exchange chromatography; trypsin

Hint 13

C

Front 14

Smokers’ lungs are often damaged by elastase because α-antitrypsin is inactive. The best explanation for this effect is that tobacco smoke _____________, which prevent it from binding to _________

Back 14

a) causes the substitution of Met for Lys in α-antitrypsin; elastase b) causes the substitution of Met for Lys in α-antitrypsin; trypsin c) causes oxidation of Met in α-antitrypsin; elastase d) causes oxidation of Met in α-antitrypsin; trypsin

Hint 14

C

Front 15

From the information given, all of the following can correctly be concluded EXCEPT

Back 15

a) The number of trypsin cleavage sites is greater in Met  Lys mutation of α-antitrypsin than in normal α-antitrypsin. b) The individuals with Met  Lys mutation of α-antitrypsin might have a bleeding disorder. c) Single-residue changes in proteins can alter substrate-binding specificity. d) Pancreas trypsin inhibitor and α-antitrypsin may have similar active sites.

Hint 15

B

Front 16

Vitamins are organic compounds required as essential nutrients in trace amounts by human. Vitamin K is required for biosynthesis of _____________ and vitamin C is ______

Back 16

a) prothrombin; required for formation of hydroxyproline b) prothrombin; a coenzyme of prolyl hydroxylase c) antithrombin; required for formation of hydroxyproline d) antithrombin; a coenzyme of prolyl hydroxylase

Hint 16

A

Front 17

Blood clotting must be precisely regulated. Specific inhibitors are critical for the regulation of clotting proteins. Antithrombin III is a specific inhibitor of thrombin. Nature of antithrombin III is ______________. This action of antithrombin III is stimulated by heparin, a polysaccharide. Thus, heparin functions in ______________ blood clotting cascade.

Back 17

a) an organic compound; inhibiting b) an organic compound; stimulating c) a protein; inhibiting d) a protein; stimulating

Hint 17

C

Front 18

You are given two statements below: A. Elastase is activated by trypsin B. Trypsin is activated by elastase Which statement is correct? Proteolytic activation of chymotrypsin from chymotrypsinogen requires cleavage of four peptide bonds. Assume that any proteases can convert 100 substrates to 100 products. Activation of one enteropeptidase can eventually lead to formation of _____________ chymotrypsin proteins

Back 18

a) A; 1,000,000 b) A; 100,000,000 c) B; 1,000,000 d) B; 100,000,000

Hint 18

A

Front 19

Polysaccharide is an important class of biological polymers. Their function in living organisms is usually either structure- or storage-related. A polysaccharide consists of many covalently linked monosaccharides. These structures are often linear, but may contain various degrees of branching. Glycogen is a polymer of ______________ with branches of ______________ . ______________ reducing ends are in a molecule of glycogen that contains 100,000 linear glucose residues with a branch every 100 glucose residues.

Back 19

a) [glucose α-1,4 glucose]n; glucose α-1,6 glucose; 1 b) [glucose α-1,4 glucose]n; glucose α-1,6 glucose; 1,000 c) [glucose α-1,6 glucose]n; glucose α-1,4 glucose; 1 d) [glucose α-1,6 glucose]n; glucose α-1,4 glucose; 1,000

Hint 19

A

Front 20

Lab scientists have synthesized a new form of maltose with an α (1, 1) glycosidic bond instead of the normal α (1, 4) linkage and also a new form of lactose with an β (1, 1) glycosidic bond instead of the normal β (1, 4) linkage. Which of the following statements about the new forms of maltose and lactose is most likely true?

Back 20

a) The new form of maltose will still be a reducing sugar while the new form of lactose will become a non-reducing sugar. b) The new form of maltose will become a non-reducing sugar while the new form of lactose will still be a reducing sugar. c) Both new forms of maltose and lactose are still reducing sugars. d) Both new forms of maltose and lactose will become non-reducing sugars.

Hint 20

D

Front 21

Back 21

a) A: lactose, B: cellobiose, C: sucrose; A and B b) A: cellobiose, B: lactose, C: sucrose; A and B c) A: lactose, B: cellobiose, C: sucrose; C d) A: cellobiose, B: lactose, C: sucrose; C

Hint 21

C

Front 22

____________ moieties of carbohydrates with five and six carbons will spontaneously reaction with ____________ groups present in neighboring carbons to produce ring structure. The rings can open and close allowing for different configurations of atoms in the ring. Glucose have linear or ring structures in water solution. Majority of glucose molecules in water are ring structures, either α or β. The predominant form of glucose in water is __________ configuration.

Back 22

a) Aldehyde; alcohol; α b) Aldehyde; alcohol; β c) Carboxyl; alcohol; α d) Carboxyl; alcohol; β

Hint 22

B

Front 23

A polysaccharide consists of many covalently linked monosaccharides. These structures are often linear, but may contain various degrees of branching. Chitin is a polymer of ______________ . Peptidoglycan is a polymer of _________

Back 23

a) [NAG β-1,4 NAG]n; [NAM β-1,4 NAG]n b) [NAM β-1,4 NAG]n; [NAG β-1,4 NAG]n c) [NAG α-1,4 NAG]n; [NAM α-1,4 NAG]n d) [NAM α-1,4 NAG]n; [NAG α-1,4 NAG]n

Hint 23

A

Front 24

Hemagglutinin and neuraminidase are influenza proteins. Influenza, commonly known as the flu, is an infectious disease of birds and mammals caused by ssRNA virus. Hemagglutinin binds carbohydrate portion of glycoprotein on the surface of a host cell through noncolvanet interactions. ______________ contains carbohydrate binding sites. Neuraminidase cleaves ______________ to free the pathogen to infect the cell.

Back 24

a) Hemagglutinin; glycosidic bonds b) Hemagglutinin; sialic acid c) The glycoprotein on the surface of a host cell; glycosidic bonds d) The glycoprotein on the surface of a host cell; sialic acid

Hint 24

A

Front 25

O-linked glycoproteins have _____________ to covalently link to carbohydrates (often directly link to mannose, N-acetylglucosamine or N-acetylgalactosamine). N-linked glycoproteins have _____________ to covalently link to carbohydrates. Blood type is determined by specific O/H, A and B antigens that are examples of glycoproteins found in red blood cells. An A-type blood person has A antigen in the blood and has enzyme A. The substrate for enzyme A is ___

Back 25

a) Asn; Ser and Thr; A antigen b) Ser and Thr; Asn; A antigen c) Asn; Ser and Thr; H antigen d) Ser and Thr; Asn; H antigen

Hint 25

D

Front 26

Blood type is determined by specific O, A and B antigens because of transcriptional regulation of enzyme A and B. An O-type blood person can transfer his/her blood to an A-type blood person because _____________. An A-type blood person can transfer his/her blood to ________

Back 26

a) an antibody against O antigen will be produced by the A-type blood person; an O-type blood person b) an antibody against O antigen would not be produced by the A-type blood person; an O- type blood person c) an antibody against O antigen will be produced by the A-type blood person; an AB-type blood person d) an antibody against O antigen would not be produced by the A-type blood person; an AB-type blood person

Hint 26

D

Front 27

Glucose is an essential substrate for metabolism of most cells. Because glucose is a polar molecule, transport through biological membranes requires specific transport proteins. GLUT4 is one of glucose transporters. GLUT4 become associated with ______________ upon the activation of Akt in response to insulin signaling, and transport glucose to cytoplasm from blood vessel. GLUT4 is primarily found in muscle cells and adipose tissue. The mechanism of glucose transport by GLUT4 is ________

Back 27

a) plasma membranes; ligand-gated channel b) plasma membranes; facilitated transport c) vesicles; ligand-gated channel d) vesicles; facilitated transport

Hint 27

B

Front 28

Nearly all of the calcium ions are sequestered inside vesicles called sarcoplasmic reticulum (SR) in human muscle cells. The Ca2+-ATPase (or Ca2+-pump) functions in transporting Ca2+ from ___________ to ___________ in order to alter Ca2+ concentration when ___________ muscles become ___________ muscles

Back 28

a) cytoplasm; sarcoplasmic reticulum; working; resting b) cytoplasm; sarcoplasmic reticulum; resting; working c) sarcoplasmic reticulum; cytoplasm; working; resting d) sarcoplasmic reticulum; cytoplasm; resting; working

Hint 28

A

Front 29

Specific channels are membrane proteins, which rapidly transport ions across biological membranes. Which of the following statements is most likely true for channels? A. Channels typically have open & closed states. Closed to open and open to closed states are often regulated. B. Channels typically have open & closed states. Closed to open states are often regulated. However, open state often spontaneously converts to closed state. Channels are often integral membrane proteins. They can move laterally in the membrane, but cannot flip-flop within the membrane. They interact with lipid bilayer mainly through ________

Back 29

a) A; hydrophobic interactions b) A; hydrogen bonds c) B; hydrophobic interactions d) B; hydrogen bonds

Hint 29

C

Front 30

Potassium channel is specific for transport of potassium ion. The conserved K+ binding site of potassium channel contains unique amino acid sequence: Thr-Val-Gly-Tyr-Gly. One potassium channel has specific sites to bind maximal four K+ ions. Close to open of K+ channel is regulated by _____________ and K+ can rapidly shift from one binding site to another one farther up the channel because of ___

Back 30

a) rotation of one positively charged subunit of K+ channel; charge repulsion b) rotation of one positively charged subunit of K+ channel; polar – polar interactions c) rotation of one negatively charged subunit of K+ channel; charge repulsion d) rotation of one negatively charged subunit of K+ channel; polar – polar interactions

Hint 30

A

Front 31

Back 31

a) Molecule A; voltage-gated Na+ channel, voltage-gated K+ channel b) Molecule A; voltage-gated K+ channel, voltage-gated Na+ channel c) Molecule B; voltage-gated Na+ channel, voltage-gated K+ channel d) Molecule B; voltage-gated K+ channel, voltage-gated Na+ channel e) Molecule C; voltage-gated Na+ channel, voltage-gated K+ channel f) Molecule C; voltage-gated K+ channel, voltage-gated Na+ channel

Hint 31

A

Front 32

Back 32

a) A, C, G, B, F, D, E b) D, E, C, G, F, A, B c) E, D, B, C, G, A, F d) E, D, C, B, G, A, F

Hint 32

D

Front 33

Back 33

a) an ATP/ADP binding site; Ca2+ binding sites; A, B, C, E, D, F b) an ATP/ADP binding site; Ca2+ binding sites; B, A, C, D, F, E c) Ca2+ binding sites; an ATP/ADP binding site; A, B, C, E, D, F d) Ca2+ binding sites; an ATP/ADP binding site; B, A, C, D, F, E

Hint 33

B

Front 34

Bacteriorhodopsin is an example of integral membrane proteins, which utilize α helices in their transmembrane regions. Bacteriorhodopsin captures light energy and uses it directly to generate _____________ . It is often coupled with __________

Back 34

a) ATPs; ATP synthase b) ATPs; lactose transporter c) proton gradient; ATP synthase d) proton gradient; lactose transporter

Hint 34

C

Front 35

All cells acquire the molecules and ions they need from their surrounding extracellular fluid. There is an unceasing traffic of molecules and ions. Na+ /K+ ATPase (or Na+/K+ pump) requires ATP for transporting ions across cell membrane. Which of the following statements: A or B, is correct about Na+/K+ ATPase? A. Na+ /K+ ATPase requires phosphorylation and dephosphorylation in order to transport Na+ and K+ ions across cell membrane. B. No phosphorylation is needed for Na+/K+ ATPase to transport Na+ and K+ ions across cell membrane. Na+ /K+ ATPase transports 3 Na+ from the _________________ of a cell and 2 K+ from the _________________ of a cell by using energy of hydrolysis of one ATP molecules

Back 35

a) A; inside to the outside; outside to the inside b) B; inside to the outside; outside to the inside c) A; outside to the inside; inside to the outside d) B; outside to the inside; inside to the outside

Hint 35

A

Front 36

Lactose permease is an example of active transporters. ____________ is required for __________ to cause a conformational change in order for a bacterial cell to transport lactose from the outside to the inside

Back 36

a) ATP; phosphorylating Glu269 of lactose permease b) ATP; phosphorylating Asp269 of lactose permease c) A proton gradient; transferring H+ to carboxylic group of Glu269 of lactose permease d) A proton gradient; transferring H+ to carboxylic group of Asp269 of lactose permease

Hint 36

C

Front 37

Gram negative bacteria are different from gram positive bacteria in that gram negative bacteria contain one peptidoglycan layer and ______________. Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer, forming the cell wall. ______________bacteria are more sensitive to penicillin because of their surface of peptidoglycan.

Back 37

a) only one lipid bilayer membrane; Gram positive b) two lipid bilayer membranes; Gram negative c) only one lipid bilayer membrane; Gram negative d) two lipid bilayer membranes; Gram positive

Hint 37

D

Front 38

All cells acquire the molecules and ions they need from their surrounding extracellular fluid. There is an unceasing traffic of molecules and ions. ABC ATPase transports molecules using energy stored in ATP. The extramembrane region of ABC ATPase contains two P-loops that interact with ATP phosphate groups. ABC ATPase _____________ and it ___

Back 38

a) undergoes protein phosphorylation; aids in cancer treatment for cancer patients b) does not undergo protein phosphorylation; aids in cancer treatment for cancer patients c) undergoes protein phosphorylation; impedes cancer treatment for cancer patients d) does not undergo protein phosphorylation; impedes cancer treatment for cancer patients

Hint 38

D

Front 39

Back 39

a) A, B, C, F, D b) B, F, A, C, D c) C, D, A, B, F d) C, D, B, F, A

Hint 39

A

Front 40

_____________ most likely contain(s) a SH2 domain because their interacting proteins have ___________

Back 40

a) Only B, and C; phosphotyrosine site(s) b) Only B, and C; phosphatidylinositol 1,4,5-triphosphate(s)) c) Only B, C and E; phosphotyrosine site(s) d) Only B, C and E; phosphatidylinositol 1,4,5-triphosphate(s)

Hint 40

C

Front 41

_________________ most likely contain(s) a PH domain because it has _________________ binding site(s).

Back 41

a) Only D; phosphatidylinositol 1,4,5-triphosphate(s) b) Only D; phosphotyrosine site(s) c) Only E; phosphatidylinositol 1,4,5-triphosphate(s) d) Only E; phosphotyrosine site(s)

a) Only D; phosphatidylinositol 1,4,5-triphosphate(s) b) Only D; phosphotyrosine site(s) c) Only E; phosphatidylinositol 1,4,5-triphosphate(s) d) Only E; phosphotyrosine site(s)

Hint 41

A

Front 42

Back 42

a) brain only; muscle and brain only b) muscle and brain only, brain only c) liver and heart only; liver only d) liver only; liver and heart only

Hint 42

C

Front 43

Back 43

a) only A and D b) only B and C c) only B and D d) only A, B and D e) All of them

Hint 43

C

Front 44

Back 44

a) ERK, ELK-1 and MEK; Grb-2, Raf, Ras and Sos b) ERK, ELK-1, MEK and Raf; Grb-2, Ras and Sos c) Grb-2, Raf, and Sos; ERK, ELK-1 and MEK d) Grb-2, and Sos; ERK, ELK-1, MEK and Raf

Hint 44

C

Front 45

The human body requires that the blood glucose level is maintained in a very narrow range. Glucose homeostasis is normally regulated by two hormones: glucagon and insulin. ____________, a peptide hormone, is synthesized in response to low blood glucose level and it is secreted from ____________ of human pancreas. ____________, a peptide hormone, is synthesized in response to high blood glucose level and it is secreted from ____________ of human pancreas

Back 45

a) Glucagon; α cells; Insulin; β cells b) Glucagon; β cells; Insulin; α cells c) Insulin; α cells; Glucagon; β cells d) Insulin; β cells; Glucagon; α cells

Hint 45

A

Front 46

Back 46

a) an active dimer and two inactive monomers; E, F, C, A, G, D, B b) an active dimer and two inactive monomers; F, E, C, A, G, D, B c) two active monomers and an inactive dimer; E, F, C, A, G, D, B d) two active monomers and an inactive dimer; F, E, C, A, G, D, B

Hint 46

D

Front 47

Back 47

a) A: αβγGDP; B: αGTP; C: βγ; amide-linked fatty acyl; thioether-linked prenyl b) A: αβγGDP; B: βγ; C: αGTP; amide-linked fatty acyl; thioether-linked prenyl c) A: αβγGDP; B: αGTP; C: βγ; thioether-linked prenyl; amide-linked fatty acyl d) A: αβγGDP; B: βγ; C: αGTP; thioether-linked prenyl; amide-linked fatty acyl

Hint 47

B

Front 48

Back 48

a) A: Grb-2; B: GDP; C: GTP; thioester-linked fatty acyl b) A: Grb-2; B: GDP; C: GTP; thioether-linked prenyl c) A: Sos; B: H2O; C: Pi; thioester-linked fatty acyl d) A: Sos; B: H2O; C: Pi; thioether-linked prenyl

Hint 48

D

Front 49

Back 49

a) Only A and C b) Only A and D c) Only B d) Only D

Hint 49

D

Front 50

Back 50

a) blood pressure; D, E, B, C, A b) blood pressure; E, C, B, D, A c) blood vessel formation; D, E, B, C, A d) blood vessel formation; E, C, B, D, A

Hint 50

B

Front 51

Why is oligo-dT column used in this experiment?

Back 51

(A) Only hnRNA will bind to oligo-dT. (B) Oligo-dT selects large RNA species. (C) Ribosomal RNA is bound to the column. (D) Intact, rather than partially hydrolyzed, RNA is retained on the column. (E) Polyadenylated RNA is purified by the procedure.

Hint 51

E

Front 52

The protein in the peak of 3 H at position 20 in Figure 2a is of lower monomeric molecular weight than the protein in Figure 1a. This suggests that ER causes proteolytic cleavage but only one of products of proteolysis appears on the gel in Figure 2a. Which of the following statements does(do) not account for the absence of a second product of proteolysis?

Back 52

(A) It was not recognized by the antibody Y. (B) It contains no leucine residues. (C) It was rapidly degraded. (D) It was too small to be retained on this gel. (E) It contains no mannose residues.

Hint 52

B & E

Front 53

If glycosylation (a process of carbohydrate covalently linking to protein) were blocked with an inhibitor, tunicamycin, in the experiment with ER, the resulting gel would display only [ 3 H]leucine labeling and most likely show which of the following characteristic profiles?

Back 53

(A) The same as Figure 1. (B) Two peaks of radiolabel, one centered at position 15 and one centered at position 20 as the position shown in Figure 1a or 2a. (C) Two peaks of radiolabel, one centered at position 20 and the other, twice the amplitude, centered at position 24 as the position shown in Figure 1a or 2a. (D) A single peak of radiolabel centered at position 20 as the position shown in Figure 1a or 2a. (E) A single peak of radiolabel centered at position 15 as the position shown in Figure 1a or 2a

Hint 53

D