Chem 20
Final Exam Review
1. What is the cellular organelle associated with energy production?
Mitochondrion
2. The ultimate source of energy for all but a very few biochemical reactions is
The sun – through the process of photosynthesis
3. The biochemical process in which simple molecules are combined to make larger ones is referred to as
Anabolism
4. The sum of all the biochemical reactions occurring in an organism is
metabolism
5. The common molecule produced from all foods at the second stage of catabolism (before Kreb’s) is
Acetyl CoA
6. The abbreviation ATP stands for
Adenosine triphosphate
7. ATP is the molecule most often used for energy transport because
The hydrolysis of the third phosphate releases a significant amount of energy and is slow except in the
presence of an enzyme.
8. Which statement concerning coenzymes and redox reactions is incorrect? Explain.
A. Oxidation can be considered as loss of hydrogen or gain of oxygen.
B. Reduction can be considered as gain of hydrogen or loss of oxygen.
C. NADè is the oxidized form of NADH.
D. An oxidation reaction cannot occur unless a reduction reaction also occurs.
E. FAD is the reduced form of FADH2.
9. Every turn of the citric acid cycle directly produces ___0__ molecule(s) of ATP.
Zero – none – not any!!!!! Kreb’s produces reduced coenzymes that can be used to
create ATP in the Ox-Phos pathway.
10. The citric acid cycle produces __reduced coenzymes_ as high energy molecules and ______CO2_ as its major
chemical waste product.
11. In steps 5-8 of the citric acid cycle, the high-energy molecules ___GTP, NADH_____,
produced, and ___oxaloacetate___ is regenerated to begin another turn of the cycle.
and __FADH2______ are
12. Which step(s) of the Kreb’s cycle is/are catalyzed by an oxidoreductase?
STEP 2, 4, 5,6,7,8
Oxidoreductases in the citric acid cycle include: isocitrate dehydrogenase, α-ketoglutarate
dehydrogenase complex, succinate dehydrogenase, and malate dehydrogenase.
13. Which step(s) of the Kreb’s cycle is/are catalyzed by an isomerase?
STEP 2
14. The fourth stage of metabolism, in which the high energy molecules from stage three are oxidized to produce ATP is
referred to as
Oxidative phosphorylation or electron transport
15. All of the following molecules are directly involved in the electron transport chain except
A. coenzyme Q B. ADP C. cytochrome c
D. hemoglobin E. H2O
16. The driving force which provides the energy for synthesis of
The concentration difference that occurs across the inner membrane of the mitochondrion that results
in hydrogen ions shuttling through the last part of the oxidative phosphorylation pathway.
17. The process of converting ADP to ATP in the mitochondrion takes place by a process known as
A. oxidative phosphorylation B. chemosmosis
C. respiration
D. reductive phosphorylation
E. chemiosmotic phosphorylation
18. The metal that acts as an electron carrier in the cytochromes in the electron transport chain is
Iron
19. After O2 has been reduced in the electron transport chain, the oxygen atoms are part of what molecules?
water
20. The most important goal of glucose metabolism is
Produce ATP for cellular energy
21. The pathway followed by glucose when energy is needed is
glycolysis
22. The pathway followed by glucose when cells have plenty of glucose available and there are adequate stores of
glycogen is
Lipogenesis (fatty acid synthesis)
23. When energy is needed and adequate oxygen is available, pyruvate is converted to acetyl CoA.
24. Which conversion is accomplished during glycolysis?
A. glucose to glycogen
D. pyruvate to glucose
B. glucose to pyruvate
E. glycogen to glucose
C. starch to glucose
25. The conversion of glucose 6-phosphate to fructose 6-phosphate in the second step of glycolysis is a(an) ______
reaction.
isomerization
26. When ATP is produced by direct transfer of a phosphate group instead of from reactions coupled to electron transport,
the process is referred to as _substrate-level phosphorylation.
27. The chemical products of glycolysis are
Pyruvate ATP and NADH
28. Which chemical is produced from pyruvate when it is metabolized in muscle cells under aerobic conditions?
Acetyl CoA
29. Which chemical is produced from pyruvate when it is metabolized in muscle cells under anaerobic conditions?
Lactic acid or lactate
30. Which chemical is produced from pyruvate when it is metabolized by yeast cells?
ethanol
31. All of the following are reactions in the oxidation of glucose which produce energy except
A. glycolysis
B. glycogenolysis
C. conversion of pyruvate to acetyl-SCoA
D. the citric acid cycle
E. reaction of reduced coenzymes in the electron transport chain
32. Hormones which regulate glucose metabolism are _______, _________, and _________.
A. insulin; cortisone; thyroxine
C. estrogen; progesterone; testosterone
E. estrogen; glucagon; epinephrine
B. insulin; glucagon; epinephrine
D. growth hormone; cortisone; thyroxine
33. In an individual who is starving or fasting, the body meets its need for glucose first by the process of __________,
and then by the process of __________.
A. glycolysis; gluconeogenesis
C. gluconeogenesis; glycogenesis
E. lipogenesis; glycogenolysis
B. glycogenolysis; gluconeogenesis
D. glycogenesis; lipogenesis
34. Which pathway converts glucose to its storage form in animals?
A. glycolysis
D. glycogenesis
B. glycogenolysis
E. lipogenesis
C. gluconeogenesis
35. Which pathway produces glucose from its storage form in animals?
A. glycolysis
B. glycogenolysis
C. gluconeogenesis D. glycogenesis
E. lipogenesis
36. Glycogen is most commonly found in _____ cells and _____ cells.
A. red blood; white blood
D. muscle; liver
B. red blood; liver C. muscle; white blood
E. bone; white blood
37. Which statement best summarizes the digestion of proteins?
A. Amine groups are removed from all amino acids.
B. All peptide linkages are hydrolyzed to produce a mixture of amino acids.
C. Proteins are denatured by stomach acid.
D. Amino acids are combined to produce proteins or enzymes.
E. None of the above.
38. All of the following are enzymes which are involved in the digestion of proteins except
A. pepsin
B. amylase
C. trypsin D. carboxypeptidase
E. chymotrypsin
39. The amino acid pool is the collection of
All free amino acids in the blood and cells available to be used for translation
40. The oxidation of amino acids requires many different pathways because of differences in the
The carbon skeletons that result from the R (or functional) groups.
41. If nitrogen is to be excreted from the body, it is converted to which chemical?
Urea
42. The enzyme involved in removing an amine group from an amino acid and transferring it to α-ketoglutarate is
classified as a transferase
43. Derivatives of vitamin _____ are often necessary as coenzymes in amino acid reactions in which amine groups are
removed.
A. A
B. B 6
C. B 12
D. C
E. D
44. The conversion of nitrogen derivatives to urea takes place in the
A. blood
B. kidneys
C. liver
D. brain
E. intestines
45. An essential amino acid is one which
A. is required for the synthesis of all proteins.
B. must be obtained in the diet because the human body cannot synthesize it.
C. can safely be omitted from the diet because the human body can produce it in unlimited amounts.
D. must be provided in the diet for individuals with specific hereditary enzyme deficiencies.
E. has a relatively simple carbon skeleton.
46. Each of the following metabolic intermediates is a precursor to one or more amino acids except
A. fumarate
D. 3-phosphoglycerate
B. α-ketoglutarate
E. pyruvate
C. oxaloacetate
47. Enzymes that hydrolyze lipids are ___lipases_____; substances that emulsify lipids are _bile salts_.
48. Which lipoprotein is used solely for the transport of exogenous lipids?
chylomicrons
49. Which lipoprotein is used to transport cholesterol to the liver to be recycled or excreted?
HDLs
50. Which lipoprotein transports cholesterol from the liver to cells where it is used for cell membranes or for steroid
synthesis?
LDLs or VLDLs
51. All of the following are possible metabolic fates of acetyl CoA except
A. synthesis of cholesterol
D. lipogenesis
B. Kreb's cycle
E. ketogenesis
C. gluconeogenesis
52. Which molecule is not associated with synthesis of triacylglycerides?
A. glycerol - phosphate
B. NADH
C. coenzyme A
D. carnitine
E. fatty acids
53. Which molecule is associated with transport of fatty acids into the mitochondrial matrix? carnitine
54. The complete oxidation of one molecule of stearic acid, an 18 carbon fatty acid, would require how many turns of the
beta-oxidation cycle?
8
55. The complete metabolism of one molecule of myristic acid a fatty acid with 14 carbons would produce how many
molecules of acetyl CoA? Show your work.
7 molecules of Acetyl CoA x 12 ATP = 84 ATP
6 molecules of FADH2 x 2 ATP =
12 ATP
6 molecules of NADH x 3 ATM =
18 ATP
114 ATP
-2 ATP for activation
112 ATP
56. Which cells predominately produce ketone bodies?
Muscles and liver
57. Which type of molecule is the major form for long term storage of chemical energy in the body?
Fat or triglycerides
58. Explain how bile salts work.
The nonpolar end attracts the nonpolar part of the triglyceride. The polar end attracts water. The bile salt
surrounds the triglyceride to form a micelle.
59. Consider nucleic acids.
a.
Draw a monomer of DNA.
c. Draw A U C G.
b. Draw a monomer of RNA.
Draw T A G C.
60. Consider the following segment of mRNA:
AUGUUUCCGAGCGCUUAG
a.
What is the sequence of DNA that this strand of mRNA was transcribed from?
b.
A mutation occurs that results in the replacement of the fifth nucleotide in the mRNA with A. What will be
the result in the protein?
61. Compare and contrast transcription and translation.
Transcription: the process in which information encoded in a DNA molecule is copied into an mRNA molecule
Translation: the process in which information encoded in an mRNA molecule is used to assemble a specific protein
They are both involve in the process of gene expression.
62. Explain energy metabolism is regulated when a cell has a high energy charge.
Chemical energy is stored in ATP only for a short time-ATP is quickly hydrolyzed. This chemical energy is used to do
chemical, mechanical and electrical work in the body and to maintain body temperature
63. Explain how energy metabolism is regulated when a cell has a high level of NAD +.
NAD+ is an co-enzyme that picked up H+ and e- to form NADH during the breaking down of carbohydrates, proteins
and fats.
64. Explain how gluconeogenesis and glycolysis are regulated so that both pathways are not stimulated at the same time.
Type of cells that can perform gluconeogenesis.
Three irreversible points in the pathway that are catalyzed by different enzymes.
The roles of ATP, NAD+ in regulating the enzymes.
65. Explain how ketogenic amino acids can be converted to triacylglycerols.
They are transaminated, the carbon skeletons are converted to AcetylCoA which is the starting material for fatty acid
synthesis (lipogenesis).
(c) 1996 Prentice-Hall, Inc. All rights reserved.