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CHEM 210 Exam 1 - 8 Questions And Answers (Verified Answers)
1. According to the Module, a compound with a molecular mass of 8,000 g/mol is considered a
macromolecule.: True
2. Biomolecules can have only two functional groups.: False
3. The following functional group is an amine.: True
4. In a eukaryotic cell, the organelles called ribosomes serve the purpose of digesting
macromolecules.: False
5. Carbon dioxide has a linear molecular shape AND has a bond angle of 180o: True
6. Of the following, is not a property of carbon.: possessing five valence
electrons
7. Which of the following is an element not typically found in living organ- isms?: Br
8. Which of the following functional groups is prominent in carbohydrates?: -
Alcohols
9. The following functional group is an example of .: Ketone
10. A is a chemical formula that shows how the atoms of a molecule are
bonded to one another.: Kekule' structure
11. In biomolecular structure, if two macromolecules interact it is called a
.: Supramolecular complex
12. An organic compound with this structure, C-OH, contains a
functional group.: Alcohol
13. Scientists refer to as the "super glue" of the chemistry.: C
20. Which of the following is not a functional group discussed in this module?-
: All of these were discussed.
21. Which number would be closest to the approximate number of ribosomes in an E. coli cell?:
22. Which of the following would most likely have a cell wall?: Fungal cells
23. Eukaryotes have molecules that provide a protective structure. This net- work, which is found in
all eukaryotes, is called the .: Cytoskele- ton
24. What is the molecule responsible for gout?: Uric acid
25. About how many different elements are found in living organisms?: 30
26. Explain the common similarity in all prokaryotic and eukaryotic cells. Ex- plain the similarity in at
least two sentences.: The fundamental similarity is that each cell type has a plasma membrane that
separates life from non-life. The plasma membrane acts as a barrier to most molecules but does have proteins that permit select molecules to cross via proteins (transporters). The plasma membrane permits the cell to have a different composition of molecules inside the cell than out and defines a space for life to occur.
27. According to the Module, are smaller elements or large elements favored in biological
molecules? Explain which one (smaller or larger) are preferred and give at least two examples of elements (smaller or larger) common in the biomolecules.: According to the Module, are smaller elements or large elements favored in biological molecules? Explain which one (smaller or larger) are preferred and give at least two examples of elements (smaller or larger) common in the biomolecules.
28. Describe at least three properties of carbon that permit it to be the basis of life.: 1. Carbon can
form strong covalent bonds with a variety of different elements.
- Besides, carbon can form double and triple bonds with other carbon atoms and other elements (N and O).
- Carbon can form long chains by forming numerous carbon-carbon bonds; we call these large molecules polymer. 4. Lastly, carbon can form cyclic structures, which are also called ring compounds.
29. What the definition of inorganic chemistry? How does it differ from organic chemistry?: Inorganic
chemistry is the study of all other elements, but carbon. Organic chemistry is the study of carbon-based compounds both in living and non-living organisms. There is no need to have separate sub-disciples for organic and inorganic chemistry, but for historical and organizational reasons, the difference exists.
30. Biochemists study the communication within and among organisms. Ac- cording to the module,
what are two other aspects of living organisms that
36. If the Ka of an acid is 5.63 x 10-3, what is the pKa?: 2.25 (-log Ka)
37. List the acids in INCREASING order of strength (weakest to strongest): Nitrous acid (Ka = 4.0 x
10-4); acetic acid (Ka = 1.7 x 10-5); phosphoric acid (Ka = 7.3 x 10-3): Acetic acid, nitrous acid, phosphoric acid
38. Elemental bromine (Br2) is a liquid at room temperature. What is the domi- nant attractive force
that exists between Br2 molecules in the liquid?: London forces
39. Which one of the following molecules can form a hydrogen bond?: NH
40. A hydrogen bond can form between a hydrogen atom bonded to nitrogen, N-H, and .: O
41. In a bond between P and Cl, there exists a difference in electronegativity resulting in partial
positive and partial negative charges. If a dipole arrow were added to this structure, which way would the arrow point?: The arrow points from N toward Br
42. The following reaction occurs in glues purchased from hardware stores. Customers use this
product to glue plastic together.: ”G is (-) and ”H is (-)
43. Which of the following is the free-energy change of a reaction?: ”G
44. Which of the following is the change in entropy of a reaction?: None of the above
45. Which buffer system is used by the blood to maintain pH balance?: Bicar- bonate buffer system
46. A buffer can neutralize only a certain amount of acid and base. We say that this is its: Buffer
capacity
47. Is a pH of 7.00 acidic, neutral, or basic?: Neutral
48. The "ion product" is equal to what value?: 1.0 x 10-
49. In equilibrium constant expressions, the concentration is expressed in units of as
indicated by the brackets [ ].: molarity
50. A pH = 5.0 indicates a concentration of OH- (in M) of : 10-
51. Which of the following compounds would not be soluble in water?: Oil
52. The hybridization of the central atom in water is .: sp
53. Four identical molecules dissolve in water. Each molecule contains both a polar portion and
nonpolar portion of structure. The four molecules interact in such a way that the nonpolar sections align. This is an example of the .: Hydrophobic effect
54. How does the strength of a hydrogen bond compare to the strength of a London Force? Also,
how about the strength of a hydrogen bond compared to a dipole-dipole force? Briefly comment on these differences.: The hydrogen bond strength is between 12 and 16 kcal, while the London force is generally less than 1 Kcal. A dipole-dipole bond usually is from 0.5 to 2.0 kcal. Also, hydrogen bonds are the strongest non-covalent force, which is illustrated by these numbers 57. : .12 [x-][H+]
C) "+"
D) entropy E) "+"
60. What is the hydrophobic effect and how does a clathrate help explain this phenomenon?: The
hydrophobic effect helps scientists explain how biological molecules form and interact. For instance, when molecules with both a nonpolar and polar regions dissolve in water, the nonpolar regions pack together. The packing of the nonpolar regions minimizes the interaction with water and the polar region interact with water, which in total is called the hydrophobic effect. The driving force behind this effect is the spontaneous drive of water to bind to itself through hydrogen bonds. To maximize the hydrogen bonds, water orders itself around the hydrophobic portion of the nonpolar regions in a cage structure also called a clathrate. In so doing, water can form bonds with itself and also permit the nonpolar regions to be dissolved.
61. he amino acids serine and threonine both contain sulfur atoms.: False
62. The following secondary structure shown below is an example of an alpha helix.: True
63. The side chain of histidine is bonded to the backbone nitrogen atom: False
64. The name of the molecule that binds to an enzyme is called the holoen- zyme.: False
65. An inhibitor that binds at the active site is a coenzyme.: False
66. Which amino acids differ by only one atom?: Ser and Cys
67. The formation of a peptide bond between two amino acids is an example of a(n) reaction.:
Condensation
68. The peptide Ala-Glu-Gly-Ala has .: Three peptide bonds
69. Formally, when there are 100 or more amino acids are covalently linked together that is called
a .: Protein
70. What unit is used by biochemists to indicate the mass of a protein?: Da
71. All of the 20 standard amino acids contain an R-group that is attached to the:
A. Carboxyl group
B. Amino group
C. ±carbon
D. ²carbon
E. It depends on the amino acid: C
72. Which of the following correctly matches the amino acid with its one letter abbreviation?: Aspartic
acid, D
73. The order of amino acids in a protein is written .: N to C-terminus
74. In one turn of a helix, there approximate amino acids.: 3.
86. Identify the types of secondary structure present in the follow Also, determine the
numbers of each type of secondary structur one alpha helix and two beta strands (or one beta sheet). Beta turns m but are not required in the answer.
87. Hemoglobin is said to be a tetramer. A) What is a tetramer? B) Structurally, a tetramer describes
what level of protein organization?: A) Simply it means that hemoglobin has four subunits or four independent polypeptide chains interacting non-covalently. Each protein molecule is composed of two copies each of two different subunits a and b. We say that hemoglobin is a tetramer because it has four polypeptide chains. B) It is describing the quaternary structure, which has two or more independent polypeptide chains that associate with one another to form a quaternary structure.
88. There are collections of protein structure that fit between true secondary and true tertiary
structure. What is the name of the collections of protein structure? Explain this type of structure.: Motifs occupy a position between secondary and tertiary. Motifs are particularly stable arrangements of secondary
structure, including the connections between them. Motifs are found in a variety of proteins from across all organisms.
89. What would "PRSGED" indicate about the structure and composition to a protein scientist?
Explain in at least two complete sentences.: The "PRSGED" is an example of protein primary structure, which is the order of amino acids in a peptide or protein. Each of the letters (i.e. P, R, ...) represents one of the 20 amino acids as a one-letter abbreviation). The order of amino acids is written from N-terminal to C-terminal. The letters in this peptide stand for Proline, Arginine, Serine, Glycine, Glutamic Acid, and Aspartic Acid.
90. What is the spot on an enzyme where reactions take place? Explain the characteristics of this
spot.: The active site is the spot on the enzyme where catalysis takes place. This area is often small when compared to the overall size of the protein. In fact, about 10 amino acids make up the active site.
91. Which of the following monosaccharides is not an aldose?: Dihydroxyace- tone
92. When two monosaccharides are epimers:: They differ only in the configura- tion about one carbon
atom
93. Which pair is anomeric?
A) D-ribose and D-galactoseB) ±D- -allose and ²-D-alloseC) D-Ribose and L-fruc- toseD) D-glucose and L-glucoseE) ±D- -idose and ²-L-idose: ±D- -allose and ²-D-al- lose
94. When forming the disaccharide maltose from two glucose monosaccha- rides:: A condensation
reaction occurs
95. Amylose and amylopectin are both polymers of:
A) ±D- -glucoseB) ²-D-glucoseC) GalactoseD) IdoseE) Maltose: ±D- -glucose
99. Which arrow correctly identifies the atom that will become the anomeric carbon?: E
100. The following monosaccharides are covalently bonded. What type of bond unites them?
A) ±1 ’B 4 ) ±1 ’C² 4 ) 1, 4D) ±1 ’E 6 ) ²1 ’ : 6 D
101. Which statement about cellulose is true?: Cellulose is found in plants
102. The polysaccharide cellulose is most chemically similar to:: Chitin
103. The organic molecule that is produced abundantly by photosynthesis is
.: Glucose
104. The "D" in the D-carbohydrates stands for:: Dextrorotatory
105. The compound not fitting the formal definition for carbohydrate is
A. C6H14O
B. C5H10O
C. C9H18O
D. C8H16O
E. C3H6O3: A
106. Which letter represents the hemiacetal bond?: C
107. What is the configuration of the following compound?
A) ±B) C² ) DD) LE) Both A and C: D
111. Some carbohydrates form a(n) structure, which resembles a
structure in proteins.
A) ±form
B) ²turn
C) ²eta-sheet
D) D-configuration
E) ±h-elix: E
112. Mutarotation is the equilibrium between structures.
A) ±and B² ) D and LC) Anomer and epimerD) Furan and pyranE) Both A and B: A
113. Carbohydrates are not used in the following function.: All of the above are functions.
114. The word saccharide means .: Sugar
115. (Short response) A hiker is lost in the wilderness and without food.
He runs across several beetles with hard chitin exoskeletons. Would he get nutrition in the form of glucose from eating these beetles? Explain.: The human enzyme cannot break down the bond between the glucose residues in chitin. The bond is a ²1 ’4,but human enzymes only act upon ± 1 ’4S. o, no he should not eat the beetles as food.
116. How are oligosaccharides and polysaccharides similar in their structure? How are they
different?: An oligosaccharide is a polymer of 2 to 20 monosaccha- rides joined together. A polysaccharide is more than 20 monosaccharides joined together. They are typically linked together by the same1 ’ 4 linkages
practically, and there are usually thousands of monosaccharides in a polysaccharide. In addition, polysaccharides can have branches in the structure, which permits them to form large complexes. In contrast, most oligosaccharides do not have branching.
117. A) Which carbon in the following molecule determines if the molecule is D or L? Indicate the
letter corresponding the correct carbon ("A", "B", etc.)
