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LESSONS - 3 to 6
THE CHEMICAL BUILDING BLOCKS OF LIVING MATERIAL.
A. CARBOHYDRATES AND LIPIDS.
A. Objectives.
-
Explain the nature of organic molecules; identify the carbon core and functional groups;
give the chemical notation for hydroxyl-, carboxyl-, amino-, sulfhydryl-, and
phosphate-groups, define and identify asymmetric carbon atoms, stereoisomers
(geometric isomers), and enantiomers.
Explain the nature of a macromolecule and polymeric molecule, how they can be
formed and dismantled; explain graphically dehydration and hydrolysis.
Give the general formula of a carbohydrate; relate the linear and ring structure of
glucose; give examples of monosaccharides, disaccharides and polysaccharides;
compare starch, amylose, amylopectin, pectins, glycogen, cellulose, mannan, chitin.
Define triglyceride, glycerol, fatty acid; compare structurally and functionally
saturated,unsaturated and polyunsaturated fatty acids; compare oils and fats and explain
their properties at different temperatures; give a graphic picture of a phospholipid;
compare the structure and properties of phospholipids and triglycerides; list examples
of complex lipids.
-
B.
Lecture outline.
1.
ORGANIC MOLECULES,.
Read:
2.
a.
structure of organic molecules.
b.
c.
polymers and macromolecules.
building macromolecules: dehydration and hydrolysis.
CARBOHYDRATES
Read:
a.
b.
c.
3.
Carbon atoms and molecules (SBM p46-50).
Carbohydrates (SBM p50-55).
simple sugars.
disaccharides.
polysaccharides.
LIPIDS.
Read:
a.
b.
c.
Lipids (SBM p56-59).
triglycerides: fats and oils.
phopholipids.
complex lipids: cholesterol, prostaglandins and carotenoids.
C.
Study Questions.
1.
Which of the following is NOT a characteristic of lipids?
A. All lipids, like carbohydrates and proteins, are made by linkage of monomers.
B.
Lipids are insoluble in water and polar compounds.
C.
Lipids have an oily consistency.
D. Lipids may exist as complex ring or linear structures and may form complexes with other types of
molecules and functional groups.
E.
A diet rich in saturated lipids may predispose to heart disease.
2.
Carbohydrates
A. contain carbon, hydrogen, nitrogen and oxygen.
B.
are involved in the storage and transmission of genetic information.
C.
can be polymers composed of monosaccharides joined by peptide bonds.
D. can combine with proteins and lipids to form glycoproteins and glycolipids.
E.
have hydrophobic monomers.
3.
Phospholipids
A. are important constituents of chromatin.
B.
have a hydrophilic and hydrophobic portion.
C.
always have saturated fatty acids.
D. are composed of glycerol attached to a single fatty acid and a substituted phosphate group.
E.
do not contain glycerol.
4.
The typical storage form of carbohydrates in plants is
A. glucose.
B.
glycogen.
c.
starch.
D. cellulose.
E.
chitin.
5.
Which of the following is NOT a common characteristic of each of the four basic biological macromolecules?
A. All contain carbon, hydrogen and oxygen.
B.
The atoms in these molecules are joined together by covalent bonds.
C.
All are polymers composed of monomers linked together.
D. All are found in every living organism.
E.
All are large molecules build from subunits.
6.
Which of the following functional groups would be least soluble in water?
A. R-CHO.
B.
R-COOH.
C.
R-CH3.
D. R-NH2.
E.
R-CH-OH.
7.
What is NOT a major macromolecule of the human body?
A. carbohydrates.
B.
lipids.
C.
nucleic acids.
D.
proteins.
E.
water.
8.
Organic compounds usually contain groups of atoms that convey certain chemical properties to the molecules;
these groups are often exchanged during chemical reactions and are called
A.
building blocks.
B.
functional groups.
C.
D.
E.
nucleic acids.
polymers.
subunits.
9.
All of the following are functional groups of organic molecules EXCEPT
A.
-CH3.
B.
-COOH.
C.
-H.
D. -NH2.
E.
-OH.
10.
Polysaccharides are polymers formed of structural units called
A. amino acids.
B.
fatty acids.
C.
nucleic acids.
D. phosphate groups.
E.
sugars.
11.
During synthesis of a polymer, two monomers are linked together by removal of
A. one of the monomers.
B.
one hydrogen from each monomer.
C.
two hydroxyl groups.
D. a molecule of water.
E.
an hydroxyl group.
12.
The breakdown of a polymer by addition of water is called
A. bond shearing.
B.
disassembly.
C.
enzyme catalysis.
D. hydrolysis.
E.
subunit recovery.
13.
Monosaccharides are
A. amino acids.
B.
simple sugars.
C.
subunits of lipids.
D. subunits of proteins.
E.
small peptides.
14.
Why are simple sugars highly water soluble? Because they
A. can exist in a linear and in a ring structure.
B.
can be condensed into polymers.
C.
have numerous hydroxyl groups.
D. have three or more carbon atoms.
E.
store energy in the cell.
15.
What is the name of sugars that possess the same number and kinds of atoms, but in a different arrangement
(e.g., glucose, fructose and galactose)?
A. Twin sugars.
B.
lactose.
C.
monomers.
D. isomers.
E.
polymers.
16.
What condensation reaction does NOT result in the formation of a
disaccharide? (Name the disaccharides!)
A. fructose + glucose.
B.
C.
D.
E.
galactose + galactose.
galactose + glucose.
glucose + glucose.
glucose + sucrose.
17.
The disaccharide of milk is called
A. fructose.
B.
maltose.
C.
glucose.
D. lactose.
E.
sucrose.
18.
A long, and sometimes branched polymer of simple sugars is a
A. disaccharide.
B.
double sugar.
C.
maltose molecule.
D. monosaccharide.
E.
polysaccharide.
19.
The glucose storage molecule of plants is
A. maltose.
B.
linoleic acid.
C.
albumin.
D. glycogen.
E.
starch.
20.
The glucose storage molecule of animal cells is
A. maltose.
B.
linoleic acid.
C.
albumin.
D. glycogen.
E.
starch.
21.
The chief structural carbohydrate constituent of plant cell walls is
A.
cellulose.
B.
chitin.
C.
starch.
D. glycogen.
E.
mannan.
22.
The structural carbohydrate of the exoskeleton of insects is
A.
cellulose.
B.
chitin.
C.
starch.
D.
glycogen.
E.
mannan.
23.
Chitin is a tough, resistant material that resembles cellulose except that the sugar moieties contain
A.
hydroxyl groups.
B.
amino groups.
C.
phosphate groups.
D.
a carbon skeleton.
E.
water molecules.
24.
Humans get little energy directly from cellulose because
A.
cellulose contains very little stored energy.
B.
cellulose is a structural, not an energy—storage material.
C.
D.
E.
humans do not have the machinery to digest cellulose.
humans do not like the taste of cellulose.
very little cellulose is found in the human diet.
25.
The principal difference between fatty acids and sugars is that fatty acids
A.
are found in cells only when food is abundant.
B.
contain less O (and more H) per C atom.
C.
are rarely found in living cells.
D.
are polymers of amino acids.
E.
contain carbon and hydrogen atoms.
26.
Which macromolecule is NOT a complex lipid?
A.
enzymes.
B.
photosynthetic pigments.
C.
prostaglandins.
D.
steroid hormones.
E.
carotenoids.
27.
Because the hydrogen/carbon ratio of fats is much higher than that of carbohydrates, fats
A.
are more soluble in water.
B.
are less soluble in a polar medium.
C.
cannot be digested by humans.
D.
tend to be highly polar molecules.
E.
are smaller molecules.
28.
Because fatty acids contain predominantly C-H bonds, fatty acids
A. are highly soluble in water.
B.
are hydrophobically excluded by water.
C.
are not found in living cells.
D.
form hydrogen bonds with one another.
E.
form hydrogen bonds with water.
29.
Three fatty acids bonded together with a glycerol form a(n)
A.
sugar.
B.
enzyme.
C.
phopholipid.
D.
nucleotide.
E.
triglyceride.
30.
The most common naturally occurring fatty acids contain
A.
no carbon atoms.
B.
1 or 2 carbon atoms.
C.
6 carbon atoms.
D.
16 or 18 carbon atoms.
E.
hundreds of carbon atoms.
31.
A fatty acid with one or more double bonds along the length of the carbon chain is
A.
unusual.
B.
saturated.
C.
a triglyceride.
D.
unsaturated.
E.
hydrophilic.
32.
A lipid that is liquid at room temperature is likely
A.
polyunsaturated.
B.
produced by plants.
C.
of shorter length.
D.
E.
both A and C.
all of the above.
33.
Phospholipids are different from triglycerides in that phospholipids
A.
have a highly polar group at one end.
B.
are often highly colored pigments.
C.
are used exclusively for energy storage.
D.
have a glycerol backbone and fatty acid tails.
E.
are not synthesized in the presence of aspirin.
35.
The molecule of a phospholipid that most resembles a sugar is (a)
A.
glycerol.
B.
fatty acid.
C.
phosphate.
D. small organic, hydrophilic molecule.
E.
glucose.
34.
Aspirin reduces pain and inflammation by inhibiting the synthesis of
A.
male and female steroid hormones.
B.
membrane lipids.
C.
prostaglandins.
D.
saturated fatty acids.
E.
triglycerides.
35.
Which of the following is not a property of carbon?
A.
Carbon-to-carbon bonds are limited to single bonds.
B.
Carbon has four valence electrons.
C.
Carbon can form bonds to various other atoms.
D.
Two carbon atoms can share three electron pairs with each other.
E.
Carbon-to-carbon bonds are strong.
36. The number of electron pairs shared between carbon 2 and 3 in the accompanying figure is:
A.
one.
B.
one and a half.
C.
two.
D.
three.
E.
None of the above.
37. The two molecules in the following figure represent:
A.
B.
C.
D.
E.
ionized structures.
enantiomers.
secondary structures.
geometric isomers.
polymers.
38. The highly polarized nature of compounds containing carboxyl groups can be attributed to the presence of two:
A.
highly electronegative carbon atoms.
B.
highly electropositive carbon atoms.
C.
highly electronegative oxygen atoms.
D.
highly electropositive oxygen atoms.
E.
highly electropositive nitrogen atoms.
39. This functional group is weakly basic because it can accept an H+ ion:
A.
hydroxyl
B.
carbonyl
C.
amino
D.
phosphate
E.
sulfhydryl
40. Hydrocarbons are hydrophobic because:
A.
the covalent bonds between hydrogen and carbon are nonpolar.
B.
they contain no functional groups.
C.
they exist as isomers.
D.
Both A and B.
E.
Both A and C.
41. The chemical interactions of large organic molecules are largely determined by:
A.
their solubility in water.
B.
their functional groups.
C.
their polar nature.
D.
isomerization of these hydrocarbons into other forms.
E.
the hydrogens bonded to the carbon atoms.
42. Which of these terms is most inclusive?
A.
monosaccharide
B.
starch
C.
polysaccharide
D.
disaccharide
E.
carbohydrate
43. Carbohydrate molecules:
A.
serve as structural components of human cell walls.
B.
form the regulatory compounds known as enzymes.
C.
are a source of energy.
D.
help protect vital organs from damage.
E.
contain the genetic information of a cell.
44. A chemical reaction in which polymers are synthesized from their building blocks is called:
A.
hydrolysis.
B.
condensation.
C.
oxidation.
D.
reduction.
E.
dissociation.
45, 46. Use the figure below to answer the corresponding questions.
45. The process illustrated in the figure is called:
A.
condensation.
B.
protein synthesis.
C.
hydrolysis.
D.
dehydration synthesis.
E.
denaturation.
46. The products of the process in the accompanying figure are:
A.
amino acids.
B.
molecules of glycerol.
C.
representative of a glycoside linkage.
D.
enzymes.
E.
monosaccharides.
47. In which of the following reactions must the equivalent of a water molecule be added in order to break a bond?
A.
fatty acids + glycerol → fat
B.
glucose + fructose → sucrose
C.
glycogen → glucose
D.
alanine + glycine → dipeptide
E.
glucose → cellulose
48. Which of the following illustrates hydrolysis?
A.
the reaction of two monosaccharides to form a disaccharide
B.
the reaction of two amino acids to form a dipeptide
C.
the reaction of a hydrogen atom and a hydroxide ion to form water
D.
the reaction of a fat to form glycerol and fatty acids
E.
the formation of ATP from ADP and inorganic phosphate
49. Glucose dissolves in water because:
A.
it ionizes.
B.
it is a polysaccharide.
C.
it has polar hydroxyl groups that interact with polar water molecules.
D.
it has a very reactive primary structure.
E.
it is hydrophobic.
50. The difference between a hexose and a pentose is that:
A.
B.
C.
D.
E.
a hexose is saturated, and a pentose is undersaturated.
a hexose is hydrophilic, and a pentose is hydrophobic.
a hexose always has six hydroxyl groups, and a pentose always has five.
a hexose always has six carbons, but a pentose always has five carbons.
a hexose can be polymerized, but a pentose cannot.
51. Monosaccharides are water soluble because:
A.
they contain a large number of methyl groups.
B.
they have a large number of polar hydroxyl groups.
C.
they have at least one double bond between adjacent carbons.
D.
they have large numbers of nonpolar carbons in their backbones.
E.
they can form ring structures.
52. Which pair is mismatched?
A.
monsaccharide—maltose
B.
disaccharide—sucrose
C.
polysaccharide—cellulose
D.
hexose—glucose
E.
pentose—ribose
53. Which one of the following carbohydrates is the most structurally complex?
A.
sucrose
B.
fructose
C.
cellulose
D.
glucose
E.
a disaccharide
54. Amyloplasts are organelles that store:
A.
fat.
B.
starch.
C.
protein.
D.
lipids.
E.
DNA.
55. A carbohydrate energy storage molecule found in animal liver and muscle cells is:
A.
starch.
B.
glycogen.
C.
cellulose.
D.
a fatty acid.
E.
cholesterol.
56. What macromolecule is composed entirely of beta-glucose units?
A.
starch
B.
chitin
C.
glycogen
D.
cellulose
E.
protein
57. Which of the following is NOT true of lipids?
A.
They store energy.
B.
They function as structural components of cellular membranes.
C.
They function as hormones.
D.
They are nonpolar.
E.
They have many oxygen-containing functional groups.
58. The hydrolysis of triacylglycerol will yield:
A.
three fatty acids and one glycerol.
B.
three glycerols and one fatty acid.
C.
two fatty acids and three glycerols.
D.
one fatty acid, one amino acid, and one glucose.
E.
one fatty acid, one phosphate, and one glycerol.
59. Which of the following molecules is not grouped with the lipids?
A.
prostaglandins
B.
steroids
C.
cholesterol
D.
carotenoids
E.
None of these; all are lipids.
60. A molecule of a saturated triacylglycerol contains:
A.
the maximum number of double bonds between carbons in the fatty acid chains.
B.
the maximum number of triple bonds between carbons in the fatty acid chains.
C.
the maximum number of hydrogen atoms in the fatty acid chains.
D.
fatty acid chains with both amino and carboxyl groups.
E.
alternating single and double bonds between carbons in the fatty acid chains.
61. Which of the following statements concerning unsaturated fats is correct?
A.
They are more common in animals.
B.
They have no double bonds in the carbon chains of their fatty acids.
C.
They are generally liquids at room temperature.
D.
They contain more hydrogen than do saturated fats having the same number of carbon atoms.
E.
They have fewer fatty acids per fat molecule than do saturated fats.
62. An amphipathic molecule has:
A.
two polar ends.
B.
two hydrophobic ends.
C.
a hydrophobic and a hydrophilic portion.
D.
only one hydrophobic end.
E.
only one hydrophilic end.
63. The major difference between a structural lipid, such as those in cell membranes, and a storage fat is the fact
that the structural lipid:
A.
most commonly contains phosphate.
B.
does not contain glycerol.
C.
has four fatty acids attached to glucose.
D.
is entirely hydrophobic.
E.
is nonpolar.
64. If you partially hydrogenate oleic acid, the resulting molecule most likely would:
A.
decrease the risk of cardiovascular disease.
B.
contain more double bonds.
C.
lose a carbon atom.
D.
lose a carboxyl group.
E.
have a double bond changed from cis to trans.
65. You isolate a compound that is insoluble in water, has alternating single and double bonds, and has a bright
orange color. You correctly conclude that this compound is a:
A.
protein.
B.
nucleic acid.
C.
polysaccharide.
D.
E.
steroid.
carotenoid.
66. Which of the following statements concerning steroids is FALSE?
A.
They can function as hormones.
B.
They are exemplified by cholesterol.
C.
They consist of four attached carbon rings.
D.
They are synthesized from isoprene units.
E.
They contain phosphodiester linkages.
67. The most abundant molecules in this structure are:
A.
structural proteins.
B.
polysaccharides.
C.
triacylglycerols.
D.
phospholipids.
E.
polypeptides.
68. Which of the following is generally considered an inorganic form of carbon?
A.
CO2
B.
C2H4
C.
CH3COOH
D.
B and C
E.
All of the preceding
69. Carbon is particularly well suited to be the backbone of organic molecules because
A. It can form both covalent bonds and ionic bonds
B. Its covalent bonds are very irregularly arranged in three-dimensional space
C. Its covalent bonds are the strongest chemical bonds known
D. It can bond to atoms of a large number of elements
E.
All the bonds it forms are polar
70. The structures depicted are
A. Enantiomers
B. Different views of the same molecule
C. Geometric (cis-trans isomers)
D. Both geometric isomers and enantiomers
E.
Structural isomers
H
CH 3
CH 3
C
C
H
H
H
H
71. Which of the following are generally hydrophobic?
A. Polar molecules and hydrocarbons
B. Ions and hydrocarbons
C. Nonpolar molecules and ions
D. Polar molecules and ions
E.
None of the preceding
72. Which of the following is a nonpolar molecule?
A. Water, H2O
B. Ammonia, NH3
C. Methane, CH4
D. Ethane, C2H6
E.
More than one of the preceding
H
CH 3
C
C
CH 3
H
H
73. Which of the following functional groups normally acts as an acid?
A. Hydroxyl
B. Carbonyl
C. Sulfhydryl
D. Phosphate
E.
Amino
74. The synthetic process by which monomers are covalently linked is
A. Hydrolysis
B. Isomerization
C. Condensation
D. Glycosidic linkage
E.
Ester linkage
75. A monosaccharide designated as an aldehyde sugar contains
A. A terminal carboxyl group
B. An internal carboxyl group
C. A terminal carbonyl group
D. An internal carbonyl group
E.
A terminal carboxyl group and an internal carbonyl group
76. Structural polysaccharides typically
A. Have extensive hydrogen bonding between adjacent molecules
B. Are much more hydrophilic than storage polysaccharides
C. Have much stronger covalent bonds than do storage polysaccharides
D. Consist of alternating alpha-glucose and beta-glucose subunits
E.
Form helical structures in the cell
77. A carboxyl group is always found in
A. Organic acids and sugars
B. Sugars and fatty acids
C. Fatty acids and amino acids
D. Alcohols
E.
Glycerol
78. Fatty acids are components of
A. Phospholipids and carotenoids
B. Carotenoids and triacylglycerol
C. Steroids and triacylglyecerol
D. Phospholipids and triacylglycerol
E.
Carotenoids and steroids
79. Saturated fatty acids are named so because they are saturated with
A. Hydrogen
B. Water
C. Hydroxyl groups
D. Glycerol
E.
Double bonds
80. Fatty acids in phospholipids and triacylglycerols interact with one another by
A. Disulfide bridges
B. Van der Waals interactions
C. Covalent bonds
D. Hydrogen bonds
E.
Fatty acids do not interact with each other