Tymoczko Biochemistry A Short Course THIRD EDITION (Six Month Access) John L. Tymoczko -Test Bank

<< Understanding Anatomy And Physiology A Visual Auditory Interactive Approach 2nd Edition Thompson Test Bank Burton Microbiology For the Health Sciences 9th edition by Paul G. Engelkirk Test Bank >>
Product Code: 222
Availability: In Stock
Price: $24.99
Qty:     - OR -   Add to Wish List
Add to Compare

Tymoczko Biochemistry A Short Course THIRD EDITION (Six Month Access) John L. Tymoczko -Test Bank



Tymoczkos Biochemistry A Short Course THIRD EDITION (Six Month Access) John L. Tymoczko -Test Bank

Chapter 2  Water, Weak Bonds, and the Generation of Order Out of Chaos



Matching Questions

Use the following to answer questions 110:


Choose the correct answer from the list below. Not all of the answers will be used.

  1. a) ionic bonds or salt bridges
  2. b) Brownian motion
  3. c) hydrophobic
  4. d) hydrogen
  5. e) polar
  6. f) nonpolar
  7. g) van der Waals
  8. h) entropy
  9. i) ion product of water
  10. j) amphipathic
  11. k) positive
  12. l) dielectric constant
  13. m) negative


1. ____________: The type of bond found between an oxygen on one water molecule and hydrogen on a different water molecule.
  Ans: d
  Section: 2.2


2. Movement of particles due to the random fluctuations of energy content of the environment is known as ____________.
  Ans: b
  Section: 2.1


3. Electrostatic interactions between atoms with opposite electrical charges are also called ____________.
  Ans: a
  Section: 2.3


4. Water weakens the electrostatic interaction of ions due to its high ____________.
  Ans: l
  Section: 2.3


5. The distance when two atoms no longer repulse each other yet have the strongest attraction is known as the____________  contact distance.
  Ans: g
  Section: 2.3


6. ____________: Thermodynamic force that drives hydrophobic interactions.
  Ans: h
  Section: 2.4


7. ____________: A molecule with two distinctive chemical properties or characteristics.
  Ans: j
  Section: 2.4


8. Which type of amino acid is responsible for increasing entropy as a protein folds?
  Ans: f
  Section: 2.4


9. ____________: The charge on acetic acid when the pH is more than one pH unit above the pKa.
  Ans: m
  Section: 2.5


10. ____________: The charge of an amino group when the pH is one pH unit below the pKa.
  Ans: k
  Section: 2.5



Fill-in-the-Blank Questions


11. Molecules that are readily soluble in water are considered      .
  Ans: polar                                            Section 2.2


12. The force that is quantified by Coulombs law is called      .
  Ans: ionic or electrostatic interaction   Section 2.3


13. A solvent with a low dielectric constant would be a       solvent for salts.
  Ans: poor                                             Section 2.3


14. The transient force, which while weak, still has a large impact on how macromolecules interact is the      .
  Ans: van der Waals interaction                        Section 2.3


15. Hydrophobic molecules are driven together by      , not because they have an affinity for each other.
  Ans: entropy                                        Section 2.4


16. Lipids that interact with both the water and the hydrophobic regions of the membrane are considered      .
  Ans: amphipathic                                 Section 2.4


17. An acid ionizes to form a proton and its      .
  Ans: base or conjugate base                 Section 2.5


18. When the pH is more than two pH units above the pKa of a carboxyl group, the acid is      .
  Ans: unprotonated                               Section 2.5


19. Buffers are critical in maintaining proper       levels in biological systems.
  Ans: pH                                               Section 2.5


20. The source of the key buffering component of blood is      .
  Ans: carbon dioxide                            Section 2.5



Multiple-Choice Questions


21. What is the H+ concentration in a urine sample that has a pH of 6?
  A) 106 M
  B) 108 M
  C) 106 M
  D) 1014 M
  E) 8 M
  Ans: A             Section: 2.5


22. Which of the following is considered a noncovalent bond?
  A) electrostatic interactions
  B) hydrogen bonds
  C) van der Waals interactions
  D) All of the above.
  E) None of the above.
  Ans: D             Section: 2.3


23. What charged group(s) is/are present in glycine at a pH of 7?
  A) NH3+
  B) COO
  C) NH2+
  D) A and B
  E) A, B, and C
  Ans: D             Section: 2.5


24. Water can form hydrogen bonds with the ___________ of another molecule.
  A) carbonyl groups
  B) amine groups
  C) aromatic rings
  D) alcohol groups
  E) A, B, and D
  Ans: E              Sections: 2.3 & 2.4


25. What pairs of atoms in nucleotide bases are involved in hydrogen bonds?
  A) NH and CO
  B) NH and SH
  C) OH and PO
  D) All of the above.
  E) None of the above.
  Ans: A             Section: 2.3


26. Typical van der Waals energies are about:
  A) 420 kJ/mol.
  B) 24 kJ/mol.
  C) 200 kJ/mol.
  D) All of the above.
  E) None of the above.
  Ans: B             Section: 12.3


27. What two properties of water are important for biological interactions?
  A) the polarity of water
  B) the density of water
  C) the cohesive properties of water
  D) A and C
  E) B and C
  Ans: D             Section: 2.2


28. List atoms commonly found in biological molecules that are often hydrogen-bond acceptors.
  A) carbon
  B) oxygen
  C) nitrogen
  D) B and C
  E) All of the above.
  Ans: D             Section: 2.3


29. What happens to nonpolar molecules in water?
  A) They dissolve independently.
  B) They aggregate together.
  C) They precipitate.
  D) All of the above.
  E) None of the above.
  Ans: B             Section: 2.3


30. What is the [A]/[HA] ratio when the weak acid is in a solution one pH unit above its pKa?
  A) 1:1
  B) 1:10
  C) 10:1
  D) 2:1
  E) None of the above.
  Ans: C             Section 2.3


31. What are the primary chemical components present in a phosphate buffer at pH 7.4?
  A) H3PO4 and PO43
  B) H2PO4 and PO43
  C) HPO4-2 and PO4-3
  D) H2PO4 and HPO42
  E) H3PO4 and HPO42
  Ans: D             Section 2.5


32. What is the concentration of acetic acid in 250 ml of a 100 mM acetate buffer at pH 4.76?
  A) 250 mM
  B) 100 mM
  C) 50 mM
  D) 75 mM
  E) There is not enough information to tell.
  Ans: C             Section 2.5


33. Climate scientists are concerned with the ongoing decrease in the pH of the Earths oceans. Based on what you know about weak acid/base equilibria, which of the following would contribute to ocean acidification?
  A) An increase in phosphate containing fertilizers from river runoff causes a shift in phosphoric acid equilibrium.
  B) An increase in atmospheric CO2 causes a shift in carbonic acid equilibrium.
  C) An increase in atmospheric SO2 emissions causes a shift in sulfuric acid equilibrium.
  D) All of the above.
  E) None of the above.
  Ans: B             Section: 2.5


34. Citric acid is an important intermediate in glucose metabolism and is synthesized in mitochondrial matrix. The three pKa values for each of the carboxylic acids are 3.1, 4.8, and 6.4. What would the charge be on a citrate molecule formed in the mitochondrial matrix where the pH is 7.8?
  A) +3
  B) +2
  C) -3
  D) -2
  E) None of the above.
  Ans: C             Section 2.5




35. A student observes that when an unknown molecule is added to water, it forms micelles. What can this student infer about this phenomenon?
  A) The unknown molecule is amphipathic.
  B) The micelle formation is driven by the resulting decrease in entropy of water.
  C) The unknown molecule forms many van der Waals interactions with water.
  D) Micelle formation is driven by the hydrophilic effect.
  E) All of the above.
  Ans: A             Section 2.4



Short-Answer Questions


36. Using Coulombs law, describe how water is an ideal solvent for the ions found in cells?
  Ans: The force that attracts two oppositely charged ions is measured by a constant a kq1q2  divided by the dielectric constant of the solvent R. This means that a solvent such as water, with a high dielectric constant, will result in a lowered attractive force between two ions dissolved in water.
  Section: 2.3


37. What is the significance of hydrogen bonding in biochemical structures such as DNA?
  Ans: The bonds are weak enough to be easily disrupted; yet when many are present in large numbers, they provide the stabilization necessary for larger structures such as DNA.
  Section: 2.3


38. What is an electrostatic interaction? Give an example.
  Ans: It is the attractive force of two oppositely charged atoms. Salts (such as NaCl) are a common example.
  Section: 2.3


39. How is water able to be a solvent for so many biological molecules?
  Ans: Many biological molecules have polar characteristics. Water is extremely polar and it is capable of competing with other polar molecules by weakening their electrostatic and hydrogen bonds. The oxygen can act as a hydrogen-bond acceptor, and the hydrogen can act as a donor.
  Section: 2.2


40. What is the net effect of many van der Waals interactions?
  Ans: At the interface of two large molecules, the numerous van der Waals interactions can substantially affect and stabilize the interaction.
  Section: 2.3


41. How is protein folding driven?
  Ans: Nonpolar amino acids associate with each other, forming the interior of folded proteins. This causes an increase in the entropy of water and thermodynamically drives protein folding.
  Section: 2.4


42. If noncovalent bonds are so much weaker than covalent bonds, how do they stabilize large biochemical structures?
  Ans: There is stability in numbers.
  Section: Introduction


43. What thermodynamic and free-energy changes participate in protein folding?
  Ans: A combination of hydrogen bonds and van der Waals forces affect enthalpy and the entropy associated with hydrophobic interactions.
  Section: 2.4


44. How do hydrophobic interactions aid in membrane formation?
  Ans: Hydrophobic interaction causes the nonpolar tails to aggregate and form the interior of the membrane. This results in a net release of heat and a favorable change in the system enthalpy.
  Section: 2.4


45. Give examples of key functional groups found in biochemistry.
  Ans: hydrophobic, hydroxyl, aldehyde, keto, carboxyl, amino, phosphoryl, sulfhydryl
  Section: 2.5, Table 2.1


46. Draw a titration curve for the ionization of acetic acid.
  Ans: The curve should look like Figure 2.12.
  Section: 2.5


47. Why are conjugate acidbase pairs so important in biological systems?
  Ans: The conjugate acidbase pairs in biological systems act as buffers. Many metabolic activities release protons, and these can combine with the conjugate base and so have little effect on the pH.
  Section: 2.5


48. Tris buffers are commonly used in biochemistry labs because they buffer within the physiological range of 7.1 to 9.1 due to a pKa of 8.1. To demonstrate the buffering capacity of Tris buffer, your biochemistry lab teaching assistant has given you one liter of a 0.1 M Tris buffer at pH 7.4. Add 2 mL of 1M HCl to this buffer and calculate what the new pH will be.
  Ans: Use the Henderson-Hasselbalch equation to determine the ratio of conjugate base to weak acid of the original solution.

7.4 = 8.1 + log [A]/[HA]

-0.7 = log [A]/[HA]

0.20/1 = [A]/[HA]

0.20/1.20 = 0.17 = % of buffer A = 0.17 (0.1M) = 0.017M A . = 0.83 = % of buffer HA = 0.83(0.1M) = 0.083 M HA

Next determine the [H+] added based on the amount and concentration of the HCl.

[HCl] = [H+] = (0.002 L) (1.0 M)/1.002 L) = .002 M

New [A] = 0.017 M 0.002 M = 0.015M A

New [HA] = 0.083 M + 0.02 M = 0.085M HA

Using the Henderson-Hasselbalch equation, recalculate the new pH.

pH = 8.1 + log (0.015)/0.08 = 7.35


  Section: 2.5



Chapter 14   Digestion: Turning a Meal into Cellular Biochemicals



Matching Questions

Use the following to answer questions 1-10:


Choose the correct answer from the list below. Not all of the answers will be used.

  1. a) ATP-dependent proton pump
  2. b) catabolism
  3. c) hydrolyzed
  4. d) pepsin
  5. e) digestion
  6. f) zymogen
  7. g) lipases
  8. h) anabolism
  9. i) carbohydrates
  10. j) lipids
  11. k) micelle
  12. l) enteropeptidase


25. ____________ is the first stage in the conversion of foods to energy.


  Ans:  e
  Section:  Introduction


26. In digestion, proteins are ____________ into their individual 20 amino acids.


  Ans:  c
  Section:  14.1


27. ____________ is the mechanism by which the stomach maintains a pH of around 12 pH units.


  Ans:  a
  Section:  14.2


28. ____________is a protease released by the stomach for digestion of protein.


  Ans:  d
  Section:  14.1


29. ____________ activation is a mechanism of permanently activating a protease by covalent modification.


  Ans:  f
  Section:  14.1


30. a Amylase begins the digestion of ____________ in the gut.


  Ans:  i
  Section:  14.3


31. ______________ These enzymes start the hydrolysis of proteins in the small intestine.


  Ans:  l
  Section:  14.1


32. ____________ are lipid vesicles that act to carry fats to the intestinal epithelium for absorption.


  Ans:  k
  Section:  14.4


33. Snake venom contains ____________, which cause hydrolysis of red blood cells.


  Ans:  g
  Section:  14.4


34. ___________ is a set of reactions that use energy and small molecules to synthesize new biomolecules.


  Ans:  h
  Section:  Introduction



Fill-in-the-Blank Questions


35.  The set of reactions that extract biologically useful energy from environmental sources is      .
  Ans: catabolism       Section:  Introduction


36.  One common motif in metabolism is that pathways are      in common ways.
  Ans: regulated        Section:  Introduction


37.  The      pH of the stomach is important for the denaturation of proteins.
  Ans:   denaturation      Section:  14.2


38.  The pancreas releases      to neutralize the acid produced in the stomach.
  Ans: sodium bicarbonate        Section:  14.2


39.  A      is an inactive enzyme that must be partially digested to attain full enzymatic activity.
  Ans:   zymogen      Section:  14.1


40.  Inactive chymotrypsinogen will be hydrolyzed to become an active enzyme called      .
  Ans:    chymotrypsin     Section:  14.1


41.  Amylase digests carbohydrates by cleaving the      bonds of starch.
  Ans:  a-1,4 glycosidic Section:  14.2


42.  The limit dextrin is material not digested by amylase due to the      .
  Ans: a-1,6 glycosidic bonds   Section:  14.3


43.  Emulsification of lipids requires what amphipathic molecule released from the gall bladder?     .
  Ans: bile salts        Section:  14.4


44.  Micelles are important for lipid absorption across the plasma membrane, but secretion into the lumen of the intestine and into the lymph system takes the formation of      .
  Ans:   chylomicrons      Section:  14.4


45.  Dietary fat is primarily transported from the gut to the      .
  Ans:  lymphatic system       Section:  14.4


46.  Snake venom has a high concentration of      , which digests the cell membrane.
  Ans:  phopholipases       Section:  14.4


47.        causes the release of digestive enzymes from the pancreas.
  Ans:    CCK     Section:  14.2


48.  Bile salts are produced from the precursor     .
  Ans:  cholesterol      Section:  14.4


49.  Protein digestion leads to release of      by intestinal mucosal cells into the blood for use by other tissues.
  Ans:  free amino acids       Section:  14.2




Multiple-Choice Questions


50.  Digestion is___________
  A) the process of breaking down large molecules in food.
  B) the salvage of metabolic intermediates.
  C) creating energy from foodstuff.
  D) the set of reactions that degrade small molecules into a few simple units.
  E) a pathway activated by steroid hormones.
  Ans:  A     Section:  Introduction


51. You are studying a metabolic pathway and are trying to decide if it is an anabolic pathway or a catabolic pathway. Which of the following would help diagnose this problem?
  A) Look for ATP requiring steps.
  B) Look for common intermediates.
  C) Look for enzymes under allosteric regulation
  D) Look for phagocytic activity.
  E) None of the above.
  Ans:  E     Section:  Introduction


52.   Digestion of which of the following involves hydrolases?
  A) carbohydrates
  B) triacylglycerols
  C)  proteins
  D) All of the above.
  E) A and C only.
  Ans:  D     Sections:  14.2, 14.3, and 14.4


53.   What is the significance of having transporters move amino acids from the lumen of the small intestine into intestinal cells but anti-porters move them then into blood?
  A) The transporters are driven by a K+/H+ATPase, which provides energy to completely deplete the intestine of all amino acids.
  B) The secondary active transport of the anti-porter moves amino acids into blood, regardless of the blood concentrations of amino acids, keeping the intestinal cell concentrations low.
  C) Peptidases in the intestinal cell membrane also act as amino acid transport channels driving amino acids into intestinal cells.
  D) The transporters on the lumen side of the intestinal cell will let oligopeptides into the cell, and the anti-porter ensures that these oligopeptides can be utilized by serum proteins.
  E) None of the above.
  Ans:  B     Section:  14.2


54.  A digestible proton pump inhibitor would likely have the following effect:
  A) undigested protein.
  B) nucleic acid hydrolysis.
  C) loss of ATP production.
  D) pepsin activation.
  E) decreasing levels of bile salts.
  Ans:  A     Section:  14.2


55.   The pancreas releases _________ to buffer the pH of the stomach juices.
  A) a strong base to counter the strong acid
  B) HCl
  C) NaHCO3
  D) pepsin
  E) ATPase activating protein
  Ans:  C     Section:  14.2


56.   Pepsin requires _________ to achieve activity.
  A) low pH
  B) partial denaturation of protein
  C) zymogen activation
  D) All of the above.
  E) None of the above.
  Ans:  D     Section:  14.2


57.   Which of the following enzymes activates trypsin?
  A) zymogenase
  B) pepsin
  C) trypsinase
  D) enteropeptidase
  E) carboxypeptidase
  Ans:  D     Section:  14.2


58. All of the following are pancreatic proteases except:
  A) pepsin.
  B) chymotrypsin.
  C) trypsin.
  D) carboxypeptidase.
  E) elastase.
  Ans:  A     Section:  14.2


59.   Complex carbohydrates are absorbed:
  A) as acetyl CoA.
  B) as starch or glycogen.
  C) as  glucose and simple sugars.
  D) as short 4-glucose residues.
  E) after the digestion of a 1,6 bonds by a amylase.
  Ans:  C     Section:  14.3



60.   Glucose transport into intestinal epithelial cells takes place by:
  A) active transport using sodium gradient.
  B) active transport using ATP as the energy source.
  C) passive transport using the glucose gradient.
  D) secondary active transport using potassium gradient.
  E) secondary active transport using the sodium glucose cotransporter.
  Ans:  E     Section:  14.3


61.   The result of lipase activity in digestion is:
  A) phopholipid head group hydrolysis.
  B) monoacylgycerol and two free fatty acids.
  C) bile salt formation.
  D) hydrolysis of membrane proteins.
  E) emulsion formation.
  Ans:  B     Section:  14.4


62.   The transport of lipids in the lymph is carried out by:
  A) lipases.
  B) micelles.
  C) cholesterol bile salt binding.
  D) chylomicrons.
  E) None of the above.
  Ans:  D     Section:  14.4


63.   Snake venoms poison is actually:
  A) a collection of digestive enzymes.
  B) repertory toxins.
  C) paralysis toxins and red blood cell poisons.
  D) All of the above.
  E) None of the above.
  Ans:  A     Section:  14.4


64.   Which of the following is released by the upper intestine and increases zymogen secretion?
  A) secritin
  B) pepsin
  C) cholecystekinin
  D) bile salts
  E) enteropeptidiase
  Ans:  C     Section:  14.2


65.   What is the advantage in synthesizing enzymes as zymogens?
  A) It allows them to be packaged in chyomicrons more easily.
  B) Zymogens can be stored for rapid release when needed.
  C) Depending on the zymogen, it can be activated by the low pH in the stomach or the high pH in the intestine.
  D) Zymogens are resistant to inactivation by kinases.
  E) Diet pills can be designed to inhibit zymogen hydrolysis.
  Ans:   B    Section:  14.1



Short-Answer Questions


66.  How are dietary proteins, carbohydrates, and lipids digested?
  Ans: In three phases where the foods are first absorbed, then broken down to smaller usable monomer components, and then converted to intermediate forms for transport to their final metabolic site.
  Sections:  Introduction, 14.1 14.5


67. How is the release of pancreatic enzymes coordinated with digestion in the stomach?
  Ans: Stretching of the upper intestine leads to endocrine cells releasing the hormone cholecystokinin (CCK). CCK acts on the pancreas causing it to release a host of digestive enzymes.
  Section:  14.2


68.  Why is the acidification of the stomach juices important for digestion of proteins?
  Ans: The proteases involved in the initial digestion of proteins into oligopeptides are most active at low pHs.  For the proteases to bind to their substrate, the digested protein must be partially denatured by the acidic condition of the stomach.
  Section:  14.2


69.  What would happen if an enzyme mutation occurred that seriously inhibited the activity of amylase?
  Ans: The carbohydrates would not be shortened to smaller simple sugars.  The result would be an inability of the lumen to transport the sugars to the blood. Osmotic changes in the gut would lead to very watery stool.
  Section:  14.3


70.  What is the role of cholesterol in digestion?
  Ans: The emulsification of lipids is required for digestion and transport of fats.  Crucial to this process are the bile salts formed from cholesterol.
  Section:  14.4


71.  What is a limit dextrin?
  Ans: material not digested by amylase due to the a 1,6 bonds
  Section:  14.3


72.  Non-fat substitutes often come with a warning of runny or watery stool.  What metabolic condition is similar?
  Ans: Steatorrhea, runny stool due to excess lipids when the bile salts necessary for emulsification and transport of lipids are inadequate.
  Section:  14.4


73.  Explain the mechanism of snake bite poisons.
  Ans: This is a problem of digestion from the inside out.  The answer should focus on the lipases causing hemolysis and the proteolysis of tissue proteins like collagen for the toxin spreading.
  Section:  14.4


74.   Why does the drug Omeprazole impact protein digestion more than lipid digestion?
  Ans: Omeprazole is an inhibitor of the K+/H+ ATPase used to reduce stomach acid formation. Most lipases act in the small intestine where the pH is high, however pepsin, a protein peptidase, acts in the stomach. Thus, raising stomach pH will inhibit pepsin activity.
  Section:  14.2


75.  What is a chylomicron?
  Ans: A complex mixture of lipid and protein formed in the lumin of the gut to transport nacent lipids through the lymph system.
  Section:  14.4



Chapter 28     Fatty Acid Synthesis



Matching Questions

Use the following to answer questions 110:


Choose the correct answer from the list below. Not all of the answers will be used.

  1. a) malonyl CoA
  2. b) three
  3. c) four
  4. d) C16-acyl ACP
  5. e) cytosol
  6. f) glycolysis
  7. g) acetyl CoA
  8. h) b-hydroxybutyrate
  9. i) acetyl CoA carboylase
  10. j) AMP-activated protein kinase
  11. k) oxaloacetate
  12. l) malic
  13. m) citrate


76. Fatty acid synthesis takes place in ________________ stages.
  Ans: b
  Section: 28.1


77. Fatty acid synthesis primarily takes place in the cellular location ________________.
  Ans: e
  Section: 28.1


78. The reaction utilizing NADP+ and malate uses the ________________ enzyme.
  Ans: l
  Section: 28.1


79. ________________ is the product of the committed step in fatty acid synthesis.
  Ans: a
  Section: 28.1


80. The committed step in fatty acid synthesis is inactivated by the regulatory enzyme ________________.
  Ans: j
  Section: 28.2


81. Thioesterase determines the acyl-chain length by cleaving ________________.
  Ans: d
  Section: 28.1


82. The date rape drug GHB is an isomer of ________________.
  Ans: h
  Section: 28.1


83. The availability of the metabolite ________________ determines whether acetyl CoA, made from fatty acids, can enter the citric acid cycle.
  Ans: k
  Section: 28.1


84. ________________ is the key regulator of fatty acid metabolism.
  Ans: i
  Section: 28.3


85. The molecule ________________ is the form in which acetyl groups are carried across the mitochondrial membrane from the matrix to the cytoplasm.
  Ans: m
  Section: 28.1



Fill-in-the-Blank Questions


86. Activation of acetyl CoA results in the production of _____.
  Ans: malonyl CoA                               Section: 28.1


87. Citrate serves as a signal for a high-energy state as it stimulates _____ .
  Ans: acetyl CoA carboxylase               Section: 28.2


88. A biotin-deficient diet may lead to an increase of cytosolic _____.
  Ans: acetyl CoA                                 Section: 28.1


89. The major product of mammalian fatty acid synthesis is _____.
  Ans: a C16 fatty acid, palmitate                                    Section: 28.2


Write a review

Your Name:

Your Review: Note: HTML is not translated!

Rating: Bad           Good

Enter the code in the box below:


Once the order is placed, the order will be delivered to your email less than 24 hours, mostly within 4 hours. 

If you have questions, you can contact us here

90. The synthesis of fatty acids takes place in the _____of the cell.
  Ans: cytoplasm                                                Section: 28.1