CH 5 STUDY GUIDE

if a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain? 150 200 75 25 50

75 100 nucleotide pairs are a total of 200 nucleotides. Because of base pairing, if there are 25 adenine there must also be 25 thymine. This leaves 200-50 = 150 nucleotides to be divided evenly between guanine and cytosine.

Which of the following statements about the formation of polypeptides from amino acids is true? A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid. Polypeptides form by condensation or hydrolysis reactions. A bond can form between any carbon and nitrogen atom in the two amino acids being joined. The reaction occurs through the addition of a water molecule to the amino acids.

A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid. (A hydroxyl group is removed from the carboxyl group of one amino acid and hydrogen is removed from the amino group of the other amino acid, allowing a bond to form between the two groups.)

What do Alzheimer's, Parkinson's, and mad cow disease have in common? All are caused by the buildup of misfolded proteins in cells. All are associated with plaque buildup in arteries (atherosclerosis). All are associated with the buildup of lipids in brain cells due to faulty lysosome activity. All cause the misfolding of nucleic acids. All are associated with the buildup of misfolded proteins in cells.

All are associated with the buildup of misfolded proteins in cells. These diseases and others are associated with a buildup of misfolded versions of various proteins within cells.

Select the statement that is incorrect. Complex sugars are carbohydrates. All carbohydrates have the general formula Cn(H2O)n. Simple sugars are carbohydrates. Simple sugars contain only carbon, oxygen, and hydrogen atoms.

All carbohydrates have the general formula Cn(H2O)n.

Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein? denaturing the protein a change in salt concentrations or pH treating the protein with a chemical that breaks hydrogen bonds heating the protein All of the listed responses are correct.

All of the listed responses are correct. All of the listed responses would affect the shape and therefore the catalytic activity of the enzymatic protein.

Which of the following is true regarding complementary base pairing in DNA and RNA molecules? Although the base pairing between two strands of DNA in a DNA molecule can be thousands to millions of base pairs long, base pairing in an RNA molecule is limited to short stretches of nucleotides in the same molecule or between two RNA molecules. Complementary base pairing promotes an antiparallel orientation in the structure of DNA and RNA molecules. Complementary base pairing within single strands of DNA and RNA gives them particular three-dimensional structures that are necessary for their function. Although a DNA molecule demonstrates complementary base pairing between two DNA polynucleotides to form a double helix, an RNA molecule can base-pair only along stretches of nucleotides in the same RNA molecule, such as in transfer RNA molecules. None of the listed responses is correct.

Although the base pairing between two strands of DNA in a DNA molecule can be thousands to millions of base pairs long, base pairing in an RNA molecule is limited to short stretches of nucleotides in the same molecule or between two RNA molecules Complementary base pairing provides an accurate way to synthesize a new DNA molecule from an existing one, and gives RNA molecules particular three-dimensional shapes necessary for their function.

Which of the following is not attached to the central carbon atom in an amino acid? An oxygen A carboxyl functional group An amino functional group A side chain ("R group")

An oxygen

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? C6H10O5 C18H32O16 C18H36O18 C18H30O15

C18H32O16

Which of the following molecules is a monosaccharide? C22H49O10N5 C6H12O6 C25H43O8 C51H98O6 C45H84O8PN

C6H12O6 Monosaccharides have molecular formulas that are multiples of CH2O.

Which part of an amino acid is always acidic? Side chain ("R group") Amino functional group Carboxyl functional group None of the above

Carboxyl functional group

High cholesterol levels are considered a major risk factor for heart disease. If it is so bad for humans, why does the body make cholesterol in the first place? Cholesterol aids in the formation of amino acids that are used to build proteins. Cholesterol is the precursor for many important molecules such as sex hormones. Cholesterol is not important for humans anymore. It is a holdover from hunter-gatherer days when food was scarce. Cholesterol is an important constituent of nucleotides. Cholesterol is an important energy storage molecule.

Cholesterol is the precursor for many important molecules such as sex hormones. Cholesterol is the basis for many steroid molecules, including sex hormones.

A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture __________. proteins cellulose DNA sucrose fatty acids

DNA The backbone of a nucleic acid consists of alternating sugar and phosphate groups.

Which of the following statements best summarizes the differences between DNA and RNA? DNA contains the base uracil, whereas RNA contains the base thymine. DNA nucleotides contain a different sugar than RNA nucleotides. DNA encodes hereditary information, whereas RNA does not. The bases in DNA contain sugars, whereas the bases in RNA do not contain sugar.

DNA nucleotides contain a different sugar than RNA nucleotides.

When a protein is denatured, why does it lose its functionality? Denaturation destroys the primary structure of the protein, and the protein breaks down to monomers. Denaturation breaks the intramolecular bonds, such as hydrogen bonds and van der Waals interactions, that hold the protein in its three-dimensional shape. Without the proper shape, the protein cannot function. The protein's pH changes, and the change causes the protein to lose its functionality. Different amino acids are substituted into the sequence, so the protein's properties change. Denaturation breaks the covalent bonds that hold the protein in its three-dimensional shape. Without the proper shape, the protein cannot function.

Denaturation breaks the intramolecular bonds, such as hydrogen bonds and van der Waals interactions, that hold the protein in its three-dimensional shape. Without the proper shape, the protein cannot function. Denaturation disrupts secondary, tertiary, and quaternary protein structure, causing the protein to lose its form, and thus its function.

Nutritionally, saturated triacylglycerols are considered to be less healthful than unsaturated triacylglycerols. What is the difference between them? Saturated triacylglycerols are liquid at room temperature. Saturated triacylglycerols are fats; unsaturated triacylglycerols are carbohydrates. Saturated triacylglycerols have more double bonds than unsaturated triacylglycerols do. For carbon skeletons of equal length, saturated triacylglycerols have more hydrogen atoms than unsaturated triacylglycerols do. All of the listed responses are correct.

For carbon skeletons of equal length, saturated triacylglycerols have more hydrogen atoms than unsaturated triacylglycerols do. Saturated triacylglycerols are saturated with hydrogen atoms.

Which of the following represents a specific description of a polypeptide? carbohydrates with a hydrogen bond holding them together organic molecules linked by dehydration reactions amino acids linked by hydrolysis organic monomers covalently bonded None of the listed responses is correct.

None of the listed responses is correct. A polypeptide is a chain of amino acids that have been linked together by dehydration reactions.

Which of the following is a true statement comparing phospholipids and triacylglycerols (fats and oils)? In nature, phospholipids occur in fused rings (sterol form), whereas triacylglycerols maintain a straight-chain form. Triacylglycerols may be saturated or unsaturated, but all phospholipids are saturated. Phospholipid molecules have a distinctly polar "head" and a distinctly nonpolar "tail," whereas triacylglycerols are predominantly nonpolar. Phospholipids are the primary storage form for fats in our bodies. Both molecules contain a phosphate group.

Phospholipid molecules have a distinctly polar "head" and a distinctly nonpolar "tail," whereas triacylglycerols are predominantly nonpolar. Triacylglycerols consist of three (nonpolar) fatty acid tails attached to a glycerol molecule. Phospholipids have two fatty acid tails and a hydrophilic head containing a negatively charged phosphate group.

Which polymers are composed of amino acids? Nucleic acids Carbohydrates Monomers Proteins

Proteins

True or false? Enzymes in the digestive tract catalyze hydrolysis reactions. True False

T

Which of the following statements about the 5' end of a polynucleotide strand of RNA is correct? The 5' end has a carboxyl group attached to the number 5 carbon of ribose. The 5' end has a hydroxyl group attached to the number 5 carbon of ribose. The 5' end has a phosphate group attached to the number 5 carbon of ribose. The 5' end has phosphate attached to the number 5 carbon of the nitrogenous base.

The 5' end has a phosphate group attached to the number 5 carbon of ribose.

Amylase is an enzyme that breaks down starch. Why cannot the same enzyme break down cellulose? The bonds between the monosaccharide monomers in cellulose are much stronger. Cellulose molecules are much too large. The monosaccharide monomers in cellulose are bonded together differently than those in starch. The enzyme cannot attack cellulose because of its helical shape. Starch is made of glucose; cellulose is made of fructose.

The monosaccharide monomers in cellulose are bonded together differently than those in starch. The glucose monomers in cellulose are bonded in a β glycosidic linkage, whereas those in starch have an α glycosidic linkage. The enzyme amylase is specific for the α glycosidic linkage.

Which of the following is the best explanation for why vegetable oil is a liquid at room temperature while animal fats are solid? Vegetable oil has more double bonds than animal fats. Vegetable oil has fewer double bonds than animal fats. Vegetable oil has longer fatty-acid tails than animal fats have. Animal fats have no amphipathic character.

Vegetable oil has more double bonds than animal fats.

If a small droplet of triacylglycerol molecules is suspended in water, the fat molecules form a "ball of spaghetti" with no particular orientation. But if a droplet of phospholipid molecules is put in water, all the molecules point outward, toward the water. Phospholipids are forced into this orientation because phospholipids have __________. three fatty acid molecules, all pointing in different directions two charged or polar ends both a saturated fatty acid and an unsaturated fatty acid two fatty acid molecules pointing in different directions a charged or polar end and an uncharged or nonpolar end

a charged or polar end and an uncharged or nonpolar end The nonpolar hydrocarbon tails of phospholipids are hydrophobic—that is, they are excluded from water. The negatively charged phosphate group and its attachments form a hydrophilic head that is attracted to water.

When nucleotides polymerize to form a nucleic acid _____. hydrogen bonds form between the bases of two nucleotides a covalent bond forms between the sugar of one nucleotide and the phosphate of a second covalent bonds form between the bases of two nucleotides a hydrogen bond forms between the sugar of one nucleotide and the phosphate of a second

a covalent bond forms between the sugar of one nucleotide and the phosphate of a second

The peptide bond is __________. a hydrogen bond joining nucleotides together to form a nucleic acid a hydrogen bond joining amino acids together to form a polypeptide a covalent bond joining nucleotides together to form a nucleic acid a covalent bond joining amino acids together to form a polypeptide a covalent bond joining simple sugars together to form a polypeptide

a covalent bond joining amino acids together to form a polypeptide The specific type of covalent bond joining two amino acids is a peptide bond.

Which of the following lists represents the chemical components of a nucleotide? a nitrogenous base, an amino acid, and a phosphate group a nitrogenous base, an amino acid, and a pentose sugar a series of nitrogenous bases, a nucleic acid backbone, and a hexose sugar a nitrogenous base, a phosphate group, and a pentose sugar a nitrogenous base, a fatty acid, and an amino acid

a nitrogenous base, a phosphate group, and a pentose sugar Each nucleotide consists of three parts: an organic molecule, called a nitrogenous base; a 5-carbon sugar, called a pentose; and a phosphate group that serves in the phosphodiester covalent bond that forms a bridge between adjacent nucleotides.

Which of the following descriptions best fits the class of molecules known as nucleotides? a sugar and a purine or pyrimidine a nitrogenous base and a phosphate group a nitrogenous base, a phosphate group, and a sugar a nitrogenous base and a sugar

a nitrogenous base, a phosphate group, and a sugar

A glucose molecule is to starch as __________. an amino acid is to a nucleic acid a steroid is to a lipid a protein is to an amino acid a nucleotide is to a nucleic acid a nucleic acid is to a polypeptide

a nucleotide is to a nucleic acid Nucleotides are the monomers that make nucleic acid polymers, just as glucose is the monosaccharide (monomer) from which starch (polymer) is constructed.

A glycosidic linkage is analogous to which of the following in proteins? a disulfide bond a β-pleated sheet a peptide bond an amino group

a peptide bond

Which one of the following is NOT a component of each monomer used to make proteins? an amino functional group, NH2 a phosphorus atom, P a side chain, R a carboxyl group, COOH

a phosphorus atom, P

Manufacturers make vegetable oils solid or semisolid at room temperature by __________. adding hydrogen atoms to the single-bonded carbon atoms of the fatty acid hydrocarbon chains adding hydrogen atoms to the fatty acid hydrocarbon chains, thereby converting carbon-carbon double bonds to single bonds removing hydrogen atoms and forming additional single bonds in the fatty acid hydrocarbon chains removing hydrogen atoms and forming additional double bonds in the fatty acid hydrocarbon chains None of the listed responses is correct.

adding hydrogen atoms to the fatty acid hydrocarbon chains, thereby converting carbon-carbon double bonds to single bonds The phrase "hydrogenated vegetable oils" found on food labels means that unsaturated fats have been synthetically converted to saturated fats by the addition of hydrogen.

Protein polymers are made up of ---- monomers.

amino acid

Starch and cellulose _____. are cis-trans isomers of each other are used for energy storage in plants are structural components of the plant cell wall are polymers of glucose

are polymers of glucose

Plant cell walls consist mainly of _____. peptidoglycan chlorophyll chitin cellulose None of the choices is correct.

cellulose Cellulose is a polysaccharide that is a major component of the tough walls that enclose plant cells.

Monomers are joined together in a reaction in which two molecules are ------ to each other through the loss of a water molecule; this is called a condensation reaction or, specifically, a dehydration reaction.

covalently bonded

Which of the following includes all of the pyrimidines found in RNA and DNA? cytosine, uracil, and guanine cytosine and uracil cytosine, uracil, and thymine cytosine and thymine

cytosine, uracil, and thymine

What is another name for a condensation reaction? dehydration monomerization hydrolysis catabolism water formation

dehydration Condensation, also called dehydration, refers to the removal of a water molecule during the linking of monomers

Which of the following is NOT a polymer? cellulose starch DNA glucose

glucose

A polysaccharide that is used for storing energy in human muscle and liver cells is __________. starch glucose glycogen chitin cellulose

glycogen Humans and other vertebrates store glucose as a polysaccharide called glycogen in their liver and muscles

Sucrose is formed when glucose is joined to fructose by a(n) _____. phosphodiester linkage ester linkage peptide linkage ionic bond glycosidic linkage

glycosidic linkage Glycosidic linkages join simple sugars to form polysaccharides.

The subunits (monomers) in cellulose are linked together by __________. glycosidic linkages peptide bonds ionic bonds phosphodiester linkages ester linkages

glycosidic linkages

Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by __________. glycosidic linkages ester linkages peptide bonds ionic bonds phosphodiester linkages

glycosidic linkages In making a fat, each of the three fatty acid molecules is bonded to a glycerol molecule by an ester linkage type of covalent bond.

Phospholipids and triglycerides both _____. have a phosphate have a glycerol backbone contain serine or some other organic compound have three fatty acids

have a glycerol backbone

The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases. hydrophilic interactions covalent bonds ionic bonds S—S bonds hydrogen bonds

hydrogen bonds

The secondary structure of a protein results from _____. hydrogen bonds peptide bonds hydrophobic interactions bonds between sulfur atoms ionic bonds

hydrogen bonds Electronegative oxygen and nitrogen atoms leave hydrogen atoms with partial positive charges.

What is the name of the process during which a bond between two monomers is broken? dehydration combustion hydrolysis condensation

hydrolysis

The fatty acid tails of a phospholipid are __________ because they __________. hydrophobic ... dissolve easily in water hydrophilic ... are easily hydrolyzed into their monomers hydrophobic ... have no charges to which water molecules can adhere hydrophobic ... consist of units assembled by dehydration reactions hydrophilic ... consist of units assembled by dehydration reactions

hydrophobic ... have no charges to which water molecules can adhere Phospholipid tails, which consist of nonpolar hydrocarbon chains, are hydrophobic.

A molecule with the chemical formula C6H12O6 is probably a _____. fatty acid polysaccharide monosaccharide nucleic acid

monosaccharide

Nucleic acid polymers are made up of --------- monomers.

nucleotide

Nucleic acids are polymers made up of which of the following monomers? sugars nucleotides nitrogenous bases amino acids

nucleotides

The building blocks or monomers of nucleic acid molecules are called _____. DNA and RNA nucleotides fatty acids pyrimidines and purines polysaccharides

nucleotides A nucleotide is a nucleic acid monomer consisting of a nitrogen base, a pentose sugar, and a phosphate group. Nucleotides joined together by covalent bonds called phosphodiester linkages form nucleic acid molecules.

Tertiary structure is NOT directly dependent on _____. hydrophobic interactions bonds between sulfur atoms hydrogen bonds ionic bonds peptide bonds

peptide bonds Peptide bonds link together the amino acids of a protein's primary structure.

A nucleotide is composed of a(n) _____. sulfhydryl group, a nitrogen-containing base, and a five-carbon sugar glycerol, a nitrogen-containing base, and a five-carbon sugar phosphate group, a nitrogen-containing base, and a five-carbon sugar amino group, a nitrogen-containing base, and a five-carbon sugar phosphate group, a nitrogen-containing base, and a hydrocarbon

phosphate group, a nitrogen-containing base, and a five-carbon sugar

Polymers of amino acids are called ---------. A protein consists of one or more polypeptides folded into specific conformations.

polypeptides

A carbohydrate that yields many monosaccharides when hydrolyzed is a ---------------

polysaccharide

Which level of protein structure do the α-helix and the β-pleated sheet represent? primary secondary tertiary quaternary

secondary

Some regions of a polypeptide may coil or fold back on themselves. This is called _____, and the coils or folds are held in place by _____. tertiary structure ... hydrogen bonds tertiary structure ... covalent bonds primary structure ... covalent bonds secondary structure ... hydrogen bonds secondary structure ... peptide bonds

secondary structure ... hydrogen bonds Secondary structure is the localized folding and/or coiling of the primary structure of a polypeptide. It results from hydrogen bonding between atoms of the polypeptide backbone.

***In what polysaccharide form do plants store glucose to be available later as an energy source? protein fatty acids cellulose glycogen starch

starch Starch is a glucose storage polymer in plants.

The polysaccharide that you are most likely to have eaten recently is __________. ribose starch lactose chitin glucose

starch Starch is a storage polysaccharide found especially in certain plant tissues.

Carbohydrates can function in which of the following ways? information storage enzymatic catalysis structural support energy storage structural support and energy storage

structural support and energy storage Carbohydrates function as both storage molecules (starch, glycogen) and structural support molecules (cellulose).

The overall three-dimensional shape of a single polypeptide is called its __________. secondary structure double helix quaternary structure tertiary structure primary structure

tertiary structure The tertiary structure is determined by hydrogen bonds, hydrophobic R groups, ionic bonds between R groups, van der Waals interactions, and disulfide bridges.

What component of amino acid structure varies among different amino acids? the long carbon-hydrogen tails of the molecule the presence of a central C atom the components of the R-group the glycerol molecule that forms the backbone of the amino acid

the components of the R-group

What is the difference between an aldose sugar and a ketose sugar? the position of the carbonyl group the number of carbons the position of the hydroxyl groups One is a ring form, the other is a linear chain/

the position of the carbonyl group

One characteristic shared by sucrose, lactose, and maltose is that __________. they all contain fructose they are all disaccharides they are all indigestible by humans they are all monosaccharides they are all polysaccharides

they are all disaccharides A disaccharide consists of two monosaccharides joined together by a glycosidic linkage.

Which of the following are pyrimidines found in the nucleic acid DNA? guanine and cytosine adenine and guanine thymine and adenine thymine and cytosine uracil and guanine

thymine and cytosine

The tertiary structure of a protein is the _____. organization of a polypeptide chain into an α-helix or β-pleated sheet order in which amino acids are joined in a polypeptide chain overall protein structure resulting from the aggregation of two or more polypeptide subunits unique three-dimensional shape of the fully folded polypeptide

unique three-dimensional shape of the fully folded polypeptide

A dehydration reaction (or condensation reaction) is the process in which _____. water molecules are produced as a polymer is formed from monomers water molecules are attracted to each other water molecules are used as a source of raw material to break down polymers to monomers the bonds between the individual monomers of a polymer are broken by the addition of water molecules None of the choices is correct.

water molecules are produced as a polymer is formed from monomers

Which of the following lists ranks these molecules in the correct order by size from smallest to largest? water, glucose, sucrose, protein protein, water, glucose, sucrose water, protein, sucrose, glucose glucose, water, sucrose, protein water, sucrose, glucose, protein

water, glucose, sucrose, protein