Biological Molecules and Their Functions Part 2

Which of these classes of biological molecules consist of both small molecules and macromolecular polymers?

a)nucleic acids
b)lipids, carbohydrates, proteins, and nucleic acids all consist of only macromolecular polymers
c)carbohydrates
d)lipids
e)proteins

Which of the following is not a polymer?

a)starch
b)glucose
c)chitin
d)cellulose
e)DNA

What is the chemical reaction mechanism by which cells make polymers from monomers?

a)dehydration reactions
b)hydrolysis
c)ionic bonding of monomers
d)phosphodiester linkages
e)the formation of disulfide bridges between monomers

How many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long?

12
11
10
9
8

Large organic molecules are usually assembled by polymerization of a few kinds of simple subunits. Which of the following is an exception to this statement?

DNA
an enzyme
a contractile protein
a steroid
cellulose

Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?

a)Dehydration reactions can occur only after hydrolysis.

b)Hydrolysis creates monomers, and dehydration reactions break down polymers.

c)Dehydration reactions eliminate water from lipid membranes, and hydrolysis makes lipid membranes water permeable.

d)Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers.

e)Dehydration reactions ionize water molecules and add hydroxyl groups to polymers; hydrolysis reactions release hydroxyl groups from polymers.

Polysaccharides, triacylglycerides, and proteins are similar in that they

a)are decomposed into their subunits by dehydration reactions.

b)are synthesized from monomers by the process of hydrolysis.

c)are synthesized from subunits by dehydration reactions.

d)are synthesized as a result of peptide bond formation between monomers.

e)all contain nitrogen in their monomer building blocks

Dehydration reactions are used in forming which of the following compounds?

a)triacylglycerides
b)polysaccharides
c)triacylglycerides and proteins only
d)proteins
e)triacylglycerides, polysaccharides, and proteins

DNAase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNAase?

a)The phosphodiester bonds between deoxyribose sugars would be broken.

b)All bases would be separated from the deoxyribose sugars.

c)The two strands of the double helix would separate.

d)The pyrimidines would be separated from the deoxyribose sugars.

e)The purines would be separated from the deoxyribose sugars.

Which of the following polymers contain nitrogen?

a)glycogen
b)chitin
c)amylopectin
d)cellulose
e)starch

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions?

a) C18H32O16
b)C18H10O15
c)C6H10O5
d)C18H36O18
e)C3H6O3

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the α form. Which of the following could amylase break down?

a)cellulose
b)starch
c)chitin
d)starch, cellulose, and chitin
e)starch and chitin only

On food packages, to what does the term insoluble fiber refer?

a)amylopectin
b)cellulose
c)polypeptides
d)chitin
e)starch

A molecule with the chemical formula is probably a

a)carbohydrate.
b)monosaccharide
c)carbohydrate and monosaccharide only.
d)carbohydrate and lipid only.
e)lipid.

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?

a)as a hexose
b)as a disaccharide
c)as a monosaccharide
d)as a pentose
e)as a polysaccharide

All of the following are polysaccharides except

a)chitin.
b)glycogen.
c)amylopectin.
d)cellulose.
e)lactose.

Which of the following is true of both starch and cellulose?

a)They are both polymers of glucose.
b)They are cis-trans isomers of each other.
c)They are both structural components of the plant cell wall.
d)They are both used for energy storage in plants.
e)They can both be digested by humans.

Which of the following is true of cellulose?

a)It is a polymer composed of enantiomers of glucose, it is a storage polysaccharide for energy in plant cells, it is digestible by bacteria in the human gut, and it is a major structural component of plant cell walls.

b)It is a storage polysaccharide for energy in plant cells.

c)It is a major structural component of plant cell walls.

d)It is digestible by bacteria in the human gut.

e)It is a polymer composed of enantiomers of glucose

Humans can digest starch but not cellulose because

a)the monomer of starch is glucose, while the monomer of cellulose is glucose with a nitrogen-containing group.

b)humans harbor starch-digesting bacteria in the digestive tract.

c)the monomer of starch is glucose, while the monomer of cellulose is galactose.

d)humans have enzymes that can hydrolyze the α glycosidic linkages of starch but not the β glycosidic linkages of cellulose.

e)humans have enzymes that can hydrolyze the β glycosidic linkages of starch but not the α glycosidic linkages of cellulose

The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA

a)is a six-carbon sugar and the sugar in RNA is a five-carbon sugar.

b)contains one less oxygen atom.

c)is in the α configuration and the sugar in RNA is in the β configuration.

d)is an aldehyde sugar and the sugar in RNA is a keto sugar.

e)can form a double-stranded molecule

If cells are grown in a medium containing radioactive 32P-labeled phosphate, which of these molecules will be labeled?

a)phospholipids
b)amylose
c)nucleic acids
d)proteins
e)both phospholipids and nucleic acids

How will brief heating (to 95°C) affect macromolecular structures in aqueous solution?

a)Starch will hydrolyze into monomeric sugars.

b)DNA duplexes will unwind and separate.

c)Proteins will unfold (denature).

d)DNA duplexes will unwind and separate, and proteins will unfold (denature).

e)Proteins will hydrolyze into amino acids

If cells are grown in a medium containing radioactive 15N, which of these molecules will be labeled?

a)both proteins and nucleic acids
b)fatty acids only
c)nucleic acids only
d)both fatty acids and proteins
e)proteins only

Which of the following is not a monomer/polymer pairing?

a)deoxyribonucleotide/DNA
b)monosaccharide/polysaccharide
c)ribonucleotide/RNA
d)triglyceride/phospholipid bilayer
e)amino acid/protein

Approximately 32 different monomeric carbohydrate subunits are found in various natural polysaccharides. Proteins are composed of 20 different amino acids. DNA and RNA are each synthesized from four nucleotides.

Among these biological polymers, which has the least structural variety?

proteins
DNA
polysaccharides
RNA

Approximately 32 different monomeric carbohydrate subunits are found in various natural polysaccharides. Proteins are composed of 20 different amino acids. DNA and RNA are each synthesized from four nucleotides.

Which class of biological polymer has the greatest functional variety?

a)proteins
b)RNA
c)DNA
d)polysaccharides

Use the following information to answer the question below.

Approximately 32 different monomeric carbohydrate subunits are found in various natural polysaccharides. Proteins are composed of 20 different amino acids. DNA and RNA are each synthesized from four nucleotides.

Professor Jamey Marth at the University of California, Santa Barbara, identified 70 molecules that are used to build cellular macromolecules and structures. These include at least 34 saccharides, 8 nucleosides, and 20 amino acids. In theory, then, which class of biological polymer has the greatest information-coding capacity?

polysaccharides
proteins
DNA
RNA

Which of the following statements concerning saturated fats is not true?

a)They are one of several factors that contribute to atherosclerosis.

b)They generally solidify at room temperature.

c)They are more common in animals than in plants.

d)They contain more hydrogen than unsaturated fats having the same number of carbon atoms.

e)They have multiple double bonds in the carbon chains of their fatty acids

A molecule with the formula is C18H36O2 probably a

nucleic acid.
hydrocarbon.
carbohydrate.
fatty acid.
protein.

Which of the following statements is true for the class of biological molecules known as lipids?

a)They are made from glycerol, fatty acids, and phosphate.

b)They are made by dehydration reactions.

c)They contain nitrogen.

d)They contain less energy than proteins and carbohydrates.

e)They are insoluble in water.

The label on a container of margarine lists "hydrogenated vegetable oil" as the major ingredient. What is the result of adding hydrogens to vegetable oil?

a)The hydrogenated vegetable oil is less likely to clog arteries.

b)The hydrogenated vegetable oil stays solid at room temperature.

c)The hydrogenated vegetable oil has a lower melting point.

d)The hydrogenated vegetable oil has more "kinks" in the fatty acid chains.

e)The hydrogenated vegetable oil has fewer trans fatty acids.

Which of the following is true regarding saturated fatty acids?

a)They are usually produced by plants.

b)They are the principal molecules in lard and butter.

c)They are the predominant fatty acid in corn oil.

d)They are usually liquid at room temperature.

e)They have double bonds between carbon atoms of the fatty acids.

Why are human sex hormones considered to be lipids?

a)They are hydrophilic compounds.
b)They are not soluble in water.
c)They are essential components of cell membranes.
d)They are made of fatty acids.
e)They contribute to atherosclerosis.

All of the following contain amino acids except

a)insulin.
b)cholesterol.
c)enzymes.
d)hemoglobin.
e)antibodies.

The bonding of two amino acid molecules to form a larger molecule requires

a)the release of a water molecule.
b)the release of a nitrous oxide molecule.
c)the addition of a nitrogen atom.
d)the release of a carbon dioxide molecule.
e)the addition of a water molecule.

There are 20 different amino acids. What makes one amino acid different from another?

a)different side chains (R groups) attached to a carboxyl carbon

b)different asymmetric carbons

c)different side chains (R groups) attached to an α carbon

d)different side chains (R groups) attached to the amino groups

e)different structural and optical isomers

Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. How many peptide bonds are present in this protein?

101
100
99
98
97

How many different kinds of polypeptides, each composed of 12 amino acids, could be synthesized using the 20 common amino acids?


12^20
20^12
20
240
4^12

Which bonds are created during the formation of the primary structure of a protein?

a)phosphodiester bonds
B)hydrogen bonds
c)disulfide bonds
d)peptide bonds
e)peptide bonds, hydrogen bonds, and disulfide bonds

What maintains the secondary structure of a protein?

a)disulfide bonds
b)hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond
c)hydrophobic interactions
d)hydrogen bonds between the R groups
e)peptide bonds

Which level of protein structure do the α helix and the β pleated sheet represent?

a)primary
b)secondary
c)tertiary
d)quaternary
e)primary, secondary, tertiary, and quaternary

Which type of interaction stabilizes the α helix and the β pleated sheet structures of proteins?

a)ionic bonds
b)peptide bonds
c)hydrophobic interactions
d)hydrogen bonds
e)disulfide bonds

The amino acids of the protein keratin are arranged predominantly in an α helix. This secondary structure is stabilized by

a)ionic bonds.
b)peptide bonds
c)hydrogen bonds.
d)covalent bonds.
e)polar bonds

The tertiary structure of a protein is the

a)order in which amino acids are joined in a polypeptide chain.

b)overall protein structure resulting from the aggregation of two or more polypeptide subunits.

c)bonding together of several polypeptide chains by weak bonds.

d)organization of a polypeptide chain into an α helix or β pleated sheet.

e)unique three-dimensional shape of the fully folded polypeptide.

What type of covalent bond between amino acid side chains (R groups) functions in maintaining a polypeptide's specific three-dimensional shape?

a)disulfide bond
b)ionic bond
c)hydrophobic interaction
d)van der Waals interaction
e)hydrogen bond

At which level of protein structure are interactions between the side chains (R groups) most important?

a)primary
b)secondary
c)tertiary
d)quaternary
e)primary, secondary, tertiary, and quaternary

The R group or side chain of the amino acid serine is -CH2-OH. The R group or side chain of the amino acid leucine is -CH2-CH(CH3)2. Where would you expect to find these amino acids in a globular protein in aqueous solution?

a)Leucine would be in the interior, and serine would be on the exterior of the globular protein.

b)Both serine and leucine would be in the interior and on the exterior of the globular protein.

c)Serine would be in the interior, and leucine would be on the exterior of the globular protein.

d)Both serine and leucine would be in the interior of the globular protein.

e)Both serine and leucine would be on the exterior of the globular protein.

Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are associated with an accumulation of misfolded polypeptides?

a)Alzheimer's and Parkinson's only
b)diabetes mellitus only
c)Alzheimer's only
d)Alzheimer's, Parkinson's, and diabetes mellitus
e)Parkinson's only

Changing a single amino acid in a protein consisting of 325 amino acids would

a)always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and sometimes affect its biological activity.

b)always alter the primary structure of the protein and disrupt its biological activity.

c)alter the primary structure of the protein but not its tertiary structure or function.

d)cause the tertiary structure of the protein to unfold.

e)always alter the biological activity or function of the protein.

Normal hemoglobin is a tetramer, consisting of two molecules of β hemoglobin and two molecules of α hemoglobin. In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits

a)altered primary structure.
b)altered tertiary structure.
c)altered quaternary structure.
d)altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered.
e)altered secondary structure.