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LESSON-9
THE CHEMICAL BUILDING BLOCKS OF LIFE.
C. NUCLEIC ACIDS.
A. objectives.
—
—
—
B.
List and draw the structure of a nucleotide; number the carbons of the pentose from 1’ to
5’; identify the phosphodiester bond between nucleotides; list the structure of ATP, NAD
and FAD; identify the high-energy bonds of ATP; why is ATP the’energy currency of
life’?
Give the essential structural characteristics of DNA; draw the molecule; list the major
differences between purines and pyrimidines; discuss the direction of nucleic acid strands.
Compare the structure of DNA and RNA.
Lecture outline.
Read:
1.
Nucleic acids (SBM p67=70)
THE BUILDING BLOCKS
a. five carbon sugar: ribose or deoxyribose.
b. phosphate group.
c. organic, cyclic, nitrogen base: purines and pyrimydines.
2.
NUCLEOTIDES
Read:
Figure 3.13 (R&J p47)
ATP Figure 7-5 (SBM p15)
cAMP Figure 3-25 (SBM p70) and Figure 6-8 (SBM p143)
NAD Figure 7-7 (SBM p160)
FAD
3.
DNA. Fig. 3.15 (R&J p48), 14.9c (R&J p286), 14.10a (R&J p287).
4.
RNA. Fig. 3.16 (R&J p49).
C.
Study Questions.
1.
A nucleotide is composed of:
A. a purine and a sugar.
B. a pyrimidine and a sugar.
C. a phosphate and a sugar.
D. sugars and amino acids.
E. a pyrimidine or purine, sugar and phosphate.
2.
When the phosphate group of one nucleotide binds to the sugar hydroxyl group of another
nucleotide, the bond is called a
A. glyceride bond.
B. ionic bond.
C. hydrogen bond.
D. peptide bond.
E.
phosphodiester bond.
3.
What cyclic nitrogen base does NOT occur in DNA?
A. adenine.
B. cytosine.
C. guanine.
D. thymine.
E. uracil
4.
What cyclic nitrogen base does NOT occur in RNA?
A. adenine.
B. cytosine.
C. guanine.
D. thymine.
E. uracil
5.
To what carbon of deoxyribose is the cyclic nitrogen base of a nucleotide connected?
A. 1’
B. 2’
C. 3’
D. 4’
E. 5’
6.
To what carbon of deoxyribose is the phosphate group of the nucleotide connected?
A. 1’
B. 2’
C. 3’
D. 4’
E. 5’
7.
To what sugar carbon of a nucleotide is the next nucleotide attached?
A. 1’
B. 2’
C. 3’
D. 4’
E. 5’
8.
The backbone of a nucleic acid is formed by alternating
A. sugar and phosphate molecules.
B. sugar, phosphate and cyclic N-bases.
C. purines and pyrimidines.
D.
E.
9.
ribose and deoxyribose molecules.
peptide bonds.
To what end of the nucleic acid can new nucleotides be attached? The
A. 1’
B. 2’
C. 3’
D. 4’
E. 5’
10. Cyclic N—bases in which a 6—ring is connected to a 5—ring are called.
A. adenines.
B. purines.
C. guanines.
D. pyrimidines.
E. cytosines.
11. Cyclic N-bases that contain only a 6-ring are called
A. thymines.
B. purines.
C. cytosines.
D. pyrimidines.
E. adenines.
12. What nucleotide(s) is(are) (a) purine base(s)?
A. adenine.
B. thymine.
C. guanine.
D. cytosine.
E. adenine and guanine.
F. thymine and cytosine.
13. What nucleotide(s) is(are) (a) pyrimidine base(s)?
A. adenine.
B. thymine.
C. guanine.
D. cytosine.
E. adenine and guanine.
F. thymine and cytosine.
14. What biologically important molecules may contain N atoms?
A. carbohydrates.
B. lipids.
C. proteins.
D. nucleic acids.
E. proteins and nucleic acids.
F. carbohydrates and proteins and nucleic acids.
15. What biologically important molecules contain S atoms?
A. carbohydrates.
B. lipids.
C. proteins.
D. nucleic acids. proteins and nucleic acids.
E. carbohydrates and proteins and nucleic acids.
16. Whatbiologically important molecules contain P atoms?
A. carbohydrates.
B.
C.
D.
E.
F.
lipids.
proteins.
nucleic acids.
proteins and nucleic acids.
carbohydrates and proteins and nucleic acids.
17. ATP is an example of a
A. sugar
B. fatty acid.
C. amino acid.
D. nucleotide.
E. nucleic acid.
18. The number of nucleotides present in NAD equals
A. 0.
B. 1.
C. 2.
D. 3.
E. 4.
19.
This molecule transmits heredity information:
A.
cholesterol.
B.
adenosine triphosphate.
C.
nucleic acid.
D.
fatty acid.
E.
polysaccharide.
20.
Which of the following statements is false?
A.
DNA is usually composed of two nucleotide strands.
B.
DNA contains deoxyribose.
C.
DNA does not normally contain uracil.
D.
The nucleotides of DNA are linked by phosphodiester linkages.
E.
DNA does not normally contain a phosphate group.
21. DNA most directly determines which _______ are made by a cell.
A.
polysaccharides
B.
polypeptides
C.
nucleotides
D.
triglycerides
E.
fatty acids
22. Which of the following statements best summarizes the differences between RNA and DNA?
A.
RNA is a protein and DNA is a nucleic acid.
B.
DNA is a polymer and RNA is a monomer.
C.
DNA comprises the genes, while RNA is a direct participant in the process of protein
synthesis.
D.
RNA is a single-stranded form of DNA.
E.
DNA is the primary energy currency of all cells.
23, 24.
Use the figure to answer the corresponding questions.
23. The molecular fragment represented in the
accompanying figure is:
A.
ATP.
B.
RNA.
C.
a protein.
D.
a nucleotide.
E.
a polysaccharide.
24. The type of connection between the atoms at
the point labeled 1 in the accompanying
figure is:
A.
a peptide bond.
B.
a glycoside linkage.
C.
a disulfide bond.
D.
a phosphodiester linkage.
E.
a hydrogen bond.
25. Analysis of a certain polymer shows that it
contains phosphate groups, ribose groups, and pyrimidines. Based on this information,
which of the following is the best description of this compound?
A.
It is most likely ribonucleic acid.
B.
It is DNA.
C.
It is an inorganic compound.
D.
It contains thymine.
E.
It is a polypeptide.
26. Which pair matches the correct macromolecule with the bond that joins its subunits?
A.
polysaccharide—peptide bond
B.
triacylglycerol—glycosidic linkage
C.
nucleic acid—phosphodiester linkage
D.
protein—ester linkage
E.
steroid—peptide bond
27. When a nucleic acid undergoes hydrolysis, the resulting subunits are:
A.
amino acids
B.
monosaccharides
C.
nucleotides
D.
fatty acids
E.
carotenoids
28. ATP is important in living organisms because:
A.
like all other nucleic acids, it stores hereditary information.
B.
like RNA, it acts as a source code for the formation of proteins.
C.
it can transfer some of its energy to other chemicals.
D.
it is an important structural component of cell membranes.
E.
it is easily converted to starch for long-term storage.
29. Which portion of the following molecule is most
directly involved in transferring energy?
A.
B.
C.
D.
E.
1
2
3
1 and 2
2 and 3
30. Each phosphodiester linkage in DNA or RNA includes a phosphate joined by covalent
bonds to
A.
B.
C.
D.
E.
Two bases
Two sugars
Two additional phosphates
A sugar, a base, and a phosphate
A sugar and a base
True/False
31. By definition, geometric isomers are mirror images of each other. __________________
32. The carboxyl group can exist in an ionized form and also in a nonionized form.
_________________
33. The phosphate group is a nonpolar group. __________________
34. Water is always released as a product in hydrolysis reactions. __________________
35. When glucose and fructose undergo condensation, maltose is produced as a product.
_______________
36. A disaccharide is composed of two monosaccharides joined by a glycosidic linkage.
_________________
37. Glycogen consists of beta-glucose monomers. __________________
38. Chitin is a polymer composed of N-acetyl glucosamine monomers. __________________
39. Fats high in unsaturated fatty acids tend to be solid at room temperature.
__________________
40. Carotenoids are composed of isoprene subunits. __________________
41. An essential amino acid is one that the body cannot synthesize in sufficient amounts.
_______________
42. A beta-pleated sheet is an example of a protein’s tertiary structure. __________________
43. Molecular chaperones mediate the folding of other protein molecules. __________________
44. A single protein may have several domains. __________________
45. A pyrimidine is double-ring molecule. __________________
46. Cyclic AMP is a type of nucleotide. __________________
Matching
Match the molecule with the appropriate word or phrase.
a. Carbohydrate
c. nucleic acid
b. Lipid
d. protein
47. most are nonpolar
48. starch
49. consist of monomers having 20 different types
50.
a beta-pleated sheet is one typical structure
51. monomers are joined by a glycosidic linkage
52. contains purines and pyrimidines
53. cellulose
54. cholesterol
55. may contain thymine
56. monomers are joined by phosphodiester linkages
57. can be denatured by temperature and/or pH
58. some are composed of fatty acids joined to glycerol