Key Concepts:
• Macromolecules are polymers, built from monomers.
• Carbohydrates serve as fuel and building material.
• Lipids are a diverse group of hydrophobic molecules.
• Proteins include a diversity of structures, resulting in a wide range of functions.
• Nucleic acids store, transmit, and help express hereditary information.
• Genomics and proteomics have transformed biological inquiry and applications.
Terms : Hide Images
| 2204836747 | Alpha | a coiled region constituting one form of the secondary structure of proteins, arising from a specific pattern of hydrogen bonding between atoms of the polypeptide backbone (not the side chains) | 0 | |
| 2204836748 | Amino Acid | an organic molecule possessing both a carboxyl and an amino group; amino acids serve as the monomers of polypeptides | 1 | |
| 2204836749 | Amino Group | a chemical group consisting of a nitrogen atom bonded to two hydrogen atoms; can act as a base in solution, accepting a hydrogen ion and acquiring a charge of 1+ | 2 | |
| 2204836750 | Antiparallel | referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5′ ? 3′ directions) | 3 | |
| 2204836751 | Beta | one form of the secondary structure of proteins in which the polypeptide chain folds back and forth; two regions of the chain lie parallel to each other and are held together by hydrogen bonds between atoms of the polypeptide backbone (not the side chains) | 4 | |
| 2204836752 | Carbohydrate | a sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides) | 5 | |
| 2204836753 | Catalyst | a chemical agent that selectively increases the rate of a reaction without being consumed by the reaction | 6 | |
| 2204836754 | Cellulose | a structural polysaccharide of plant cell walls, consisting of glucose monomers joined by β glycosidic linkages | 7 | |
| 2204836755 | Chaperonin | a protein complex that assists in the proper folding of other proteins | 8 | |
| 2204836756 | Chitin | a structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods | 9 | |
| 2204836757 | Cholesterol | a steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids, such as many hormones | 10 | |
| 2204836758 | Dehydration Reaction | a chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule | 11 | |
| 2204836759 | Denaturation | in proteins, a process in which a protein loses its native shape due to the disruption of weak chemical bonds and interactions, thereby becoming biologically inactive; in DNA, the separation of the two strands of the double helix; denaturation occurs under extreme (noncellular) conditions of pH, salt concentration, or temperature | 12 | |
| 2204836760 | Deoxyribonucleic acid (DNA) | a nucleic acid molecule, usually a double-stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T); capable of being replicated and determining the inherited structure of a cell's proteins | 13 | |
| 2204836761 | Deoxyribose | the sugar component of DNA nucleotides, having one fewer hydroxyl group than ribose, the sugar component of RNA nucleotides | 14 | |
| 2204836762 | Disaccharide | a double sugar, consisting of two monosaccharides joined by a glycosidic linkage formed by a dehydration reaction | 15 | |
| 2204836763 | Disulfide Bridge | a strong covalent bond formed when the sulfur of one cysteine monomer bonds to the sulfur of another cysteine monomer | 16 | |
| 2204836764 | DNA (deoxyribonucleic acid) | a nucleic acid molecule, usually a double-stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T); capable of being replicated and determining the inherited structure of a cell's proteins | 17 | |
| 2204836765 | Double Helix | the form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape | 18 | |
| 2204836766 | Enzyme | a macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. Most enzymes are proteins | 19 | |
| 2204836767 | Fat | a lipid consisting of three fatty acids linked to one glycerol molecule; also called a triacylglycerol or triglyceride | 20 | |
| 2204836768 | Fatty Acid | a carboxylic acid with a long carbon chain; fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form a fat molecule, also called triacylglycerol or triglyceride | 21 | |
| 2204836769 | Gene | a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses) | 22 | |
| 2204836770 | Gene Expression | the process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs | 23 | |
| 2204836771 | Glycogen | an extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch | 24 | |
| 2204836772 | Glycosidic Linkage | a covalent bond formed between two monosaccharides by a dehydration reaction | 25 | |
| 2204836773 | Hydrolysis | a chemical reaction that breaks bonds between two molecules by the addition of water; functions in disassembly of polymers to monomers | 26 | |
| 2204836774 | Hydrophobic | having no affinity for water; tending to coalesce and form droplets in water | 27 | |
| 2204836775 | Hydrophobic Interaction | a type of weak chemical interaction caused when molecules that do not mix with water coalesce to exclude water | 28 | |
| 2204836776 | Lipid | any of a group of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all, with water | 29 | |
| 2204836777 | Macromolecule | a giant molecule formed by the joining of smaller molecules, usually by a dehydration reaction; polysaccharides, proteins, and nucleic acids are macromolecules | 30 | |
| 2204836778 | Monomer | the subunit that serves as the building block of a polymer | 31 | |
| 2204836779 | Monosaccharide | the simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides; also called simple sugars, monosaccharides have molecular formulas that are generally some multiple of CH2O | 32 | |
| 2204836780 | Nucleic Acid | a polymer (polynucleotide) consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities. The two types are DNA and RNA | 33 | |
| 2204836781 | Nucleotide | the building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one or more phosphate groups | 34 | |
| 2204836782 | Peptide Bond | the covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction | 35 | |
| 2204836783 | Phospholipid | a lipid made up of glycerol joined to two fatty acids and a phosphate group; the hydrocarbon chains of the fatty acids act as nonpolar, hydrophobic tails, while the rest of the molecule acts as a polar, hydrophilic head; phospholipids form bilayers that function as biological membranes | 36 | |
| 2204836784 | Polymer | a long molecule consisting of many similar or identical monomers linked together by covalent bonds | 37 | |
| 2204836785 | Polynucleotide | a polymer consisting of many nucleotide monomers in a chain; the nucleotides can be those of DNA or RNA | 38 | |
| 2204836786 | Polypeptide | a polymer of many amino acids linked together by peptide bonds | 39 | |
| 2204836787 | Polysaccharide | a polymer of many monosaccharides, formed by dehydration reactions | 40 | |
| 2204836788 | Primary Structure | the level of protein structure referring to the specific linear sequence of amino acids | 41 | |
| 2204836789 | Protein | a biologically functional molecule consisting of one or more polypeptides folded and coiled into a specific three-dimensional structure | 42 | |
| 2204836790 | Proteomics | the systematic study of sets of proteins and their properties, including their abundance, chemical modifications, and interactions | 43 | |
| 2204836791 | Purine | one of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring fused to a five-membered ring; adenine (A) and guanine (G) are purines | 44 | |
| 2204836792 | Pyrimidine | one of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring; cytosine (C), thymine (T), and uracil (U) are pyrimidines | 45 | |
| 2204836793 | Quaternary Structure | the particular shape of a complex, aggregate protein, defined by the characteristic three-dimensional arrangement of its constituent subunits, each a polypeptide | 46 | |
| 2204836794 | Ribonucleic Acid (RNA) | a type of nucleic acid consisting of a polynucleotide made up of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis, in gene regulation, and as the genome of some viruses | 47 | |
| 2204836795 | Ribose | the sugar component of RNA nucleotides | 48 | |
| 2204836796 | Saturated Fatty Acid | a fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that are attached to the carbon skeleton | 49 | |
| 2204836797 | Secondary Structure | regions of repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bonding between constituents of the backbone (not the side chains) | 50 | |
| 2204836798 | Sickle-Cell Disease | a recessively inherited human blood disorder in which a single nucleotide change in the β-globin gene causes hemoglobin to aggregate, changing red blood cell shape and causing multiple symptoms in afflicted individuals | 51 | |
| 2204836799 | Starch | a storage polysaccharide in plants, consisting entirely of glucose monomers joined by α glycosidic linkages | 52 | |
| 2204836800 | Tertiary Structure | the overall shape of a protein molecule due to interactions of amino acid side chains, including hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges | 53 | |
| 2204836801 | Trans Fat | an unsaturated fat, formed artificially during hydrogenation of oils, containing one or more trans double bonds | 54 | |
| 2204836802 | Unsaturated Fatty Acid | a fatty acid that has one or more double bonds between carbons in the hydrocarbon tail; such bonding reduces the number of hydrogen atoms attached to the carbon skeleton | 55 | |
| 2204836803 | X-Ray Crystallography | a technique used to study the three-dimensional structure of molecules; it depends on the diffraction of an X-ray beam by the individual atoms of a crystallized molecule | 56 | |
| 2204836804 | What is the process by which monomers are linked together to form polymers? a. protein formation b. coiling c. monomerization d. dehydration reaction e. hydrolysis | dehydration reaction When monomers are linked together to form a more complex polymer, a water molecule is removed by dehydration reactions. | 57 | |
| 2204836805 | In a hydrolysis reaction, __________, and in this process water is __________. a. monomers are assembled to produce a polymer ... produced b. a monomer is broken up into its constituent polymers ... produced c. a polymer is broken up into its constituent monomers ... consumed d. monomers are assembled to produce a polymer ... consumed e. a polymer is broken up into its constituent monomers ... produced | a polymer is broken up into its constituent monomers ... consumed The meaning of hydrolysis is "to break with water." | 58 | |
| 2204836806 | The type of bond that forms to join monomers (such as sugars and amino acids) into polymers (such as starch and proteins) is a(n) __________ bond. a. covalent b. van der Waals c. hydrogen d. peptide e. ionic | covalent Monomers are joined together by a dehydration reaction in which two molecules are covalently bonded to each other through the loss of a water molecule. | 59 | |
| 2204836807 | Which of the following is a polymer? a. triacylglycerol, or fat b. fructose, a component of sucrose c. glucose, an energy-rich molecule d. testosterone, a steroid hormone e. cellulose, a plant cell wall component | cellulose, a plant cell wall component The polysaccharide cellulose is a major component of plant cell walls. It is a polymer composed of many glucose monomers joined together by glycosidic linkages. | 60 | |
| 2204836808 | Cellulose is a __________ made of many __________. a. protein ... amino acids b. lipid ... triacylglycerols c. polypeptide ... monomers d. polymer ... glucose molecules e. carbohydrate ... fatty acids | polymer ... glucose molecules Cellulose is a polysaccharide and therefore a polymer, constructed from many monosaccharide glucose monomers. | 61 | |
| 2204836809 | Generally, animals cannot digest (hydrolyze) the glycosidic linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass? a. They have to eat a lot of grass. b. Cows and other herbivores are exceptions and make some cellulose-digesting enzymes. c. Microorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units. d. The flat teeth and strong stomach of herbivores break the cellulose fibers so that the cows get enough nutrition from the cell contents. e. All of the listed responses are correct. | Microorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units. Cows have digestive chambers populated by microorganisms that can produce certain hydrolytic enzymes that cows cannot. The enzymes hydrolyze (digest) the cellulose polymer into glucose monomers. | 62 | |
| 2204836810 | In what polysaccharide form do plants store glucose to be available later as an energy source? a. protein b. starch c. fatty acids d. cellulose e. glycogen | starch Starch is a glucose storage polymer in plants. | 63 | |
| 2204836811 | Which of the following carbohydrate molecules has the lowest molecular mass? a. glucose b. chitin c. sucrose d. cellulose e. lactose | glucose Glucose is a monosaccharide. | 64 | |
| 2204836812 | Which of the following molecules is a monosaccharide? a. C25H43O8 b. C22H49O10N5 c. C51H98O6 d. C6H12O6 e. C45H84O8PN | C6H12O6 Monosaccharides have molecular formulas that are multiples of CH2O. | 65 | |
| 2204836813 | At a conference, the speaker's grand finale was sautéing mealworms (insect larvae) in butter and serving them to the audience. They were crunchy (like popcorn hulls) because their exoskeletons contain the polysaccharide __________. a. collagen b. palmitic acid c. glycogen d. cellulose e. chitin | chitin Chitin is the structural polysaccharide found in arthropod exoskeletons. | 66 | |
| 2204836814 | Carbohydrates are used in our bodies mainly for __________. a. membrane construction b. building genetic material c. energy storage and release d. lipid storage e. structural molecules, such as hair and fingernails | energy storage and release Simple sugar molecules, stored in polysaccharides such as glycogen in animals and starch in plants, are a major energy source for cellular work. | 67 | |
| 2204836815 | The polysaccharide that you are most likely to have eaten recently is __________. a. ribose b. lactose c. glucose d. starch e. chitin | starch Starch is a storage polysaccharide found especially in certain plant tissues. | 68 | |
| 2204836816 | One characteristic shared by sucrose, lactose, and maltose is that __________. a. they are all indigestible by humans b. they are all monosaccharides c. they are all disaccharides d. they are all polysaccharides e. they all contain fructose | they are all disaccharides A disaccharide consists of two monosaccharides joined together by a glycosidic linkage. | 69 | |
| 2204836817 | A polysaccharide that is used for storing energy in human muscle and liver cells is __________. a. glycogen b. chitin c. starch d. cellulose e. glucose | glycogen Humans and other vertebrates store glucose as a polysaccharide called glycogen in their liver and muscles. | 70 | |
| 2204836818 | Carbohydrates can function in which of the following ways? a. structural support b. energy storage c. enzymatic catalysis d. information storage e. structural support and energy storage | structural support and energy storage Carbohydrates function as both storage molecules (starch, glycogen) and structural support molecules (cellulose). | 71 | |
| 2204836819 | In a 1-4 glycosidic linkage, __________. a. one glycerol molecule is bound to four fatty acids b. the number 1 carbon in one nucleotide is bound to the number 4 carbon in another nucleotide c. the number 1 carbon in one monosaccharide is bound to the number 4 carbon in another monosaccharide d. one monosaccharide is bound to four others e. there are four possible isomers of the structure | the number 1 carbon in one monosaccharide is bound to the number 4 carbon in another monosaccharide Glycosidic linkages, the covalent bonds that link simple sugars, are named according to the carbon atoms they join. | 72 | |
| 2204836820 | Amylase is an enzyme that breaks down starch. Why cannot the same enzyme break down cellulose? a. The bonds between the monosaccharide monomers in cellulose are much stronger. b. The enzyme cannot attack cellulose because of its helical shape. c. The monosaccharide monomers in cellulose are bonded together differently than those in starch. d. Starch is made of glucose; cellulose is made of fructose. e. Cellulose molecules are much too large. | 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. | 73 | |
| 2204836821 | The subunits (monomers) in cellulose are linked together by __________. a. peptide bonds b. glycosidic linkages c. ionic bonds d. phosphodiester linkages e. ester linkages | glycosidic linkages The glucose monomers of cellulose are linked together by a specific type of covalent bond known as a glycosidic linkage. | 74 | |
| 2204836822 | Which of the following components of a tossed salad will pass through the human digestive tract and be digested the least? a. starch (in the croutons) b. cellulose (in the lettuce) c. sugar (in the dressing) d. oil (in the dressing) e. protein (in the bacon bits) | cellulose (in the lettuce) Cellulose contains glycosidic linkages that cannot be broken by human digestive enzymes. | 75 | |
| 2204836823 | What is a distinguishing feature of most naturally occurring unsaturated fats? a. They all share four fused rings as a carbon skeleton. b. They are distinguished from other lipid forms by their chief role as components of cell membranes. c. All organisms share an equal ratio of saturated and unsaturated fatty acids. d. Nearly all naturally occurring unsaturated fats have cis double bonds. e. Most unsaturated fats have trans double bonds, causing a kink in the hydrocarbon chain wherever they occur. | Nearly all naturally occurring unsaturated fats have cis double bonds. Naturally occurring unsaturated fats, such as those found in plants and fish, are distinguished by the presence of one or more cis double bonds in their hydrocarbon chains. | 76 | |
| 2204836824 | Lipids differ from other large biological molecules in that they __________. a. are much larger b. do not contain nitrogen and phosphorus atoms c. are not truly polymers d. do not contain carbon e. do not have specific shapes | are not truly polymers Lipids are not all made of the same type of monomer. Their association as a group (fats, phospholipids, and steroids) is related to their solubility behavior. | 77 | |
| 2204836825 | Which of the following terms can be correctly used to describe compounds that do NOT mix with water? a. proteins b. hydrophilic c. hydrogen-bonded d. hydrophobic e. phospholipids | hydrophobic Hydrophobic compounds are those that are insoluble in water. | 78 | |
| 2204836826 | Nutritionally, saturated triacylglycerols are considered to be less healthful than unsaturated triacylglycerols. What is the difference between them? a. Saturated triacylglycerols have more double bonds than unsaturated triacylglycerols do. b. Saturated triacylglycerols are liquid at room temperature. c. Saturated triacylglycerols are fats; unsaturated triacylglycerols are carbohydrates. d. For carbon skeletons of equal length, saturated triacylglycerols have more hydrogen atoms than unsaturated triacylglycerols do. e. 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. | 79 | |
| 2204836827 | The lipids that form the main structural component of cell membranes are __________. a. carbohydrates b. proteins c. triacylglycerols d. cholesterol e. phospholipids | phospholipids Phospholipids have a hydrophilic head and two hydrophobic tails. This permits the phospholipids to be arranged in a bilayer, or double layer, which forms a boundary between the cell and its external environment. | 80 | |
| 2204836828 | 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 __________. a. both a saturated fatty acid and an unsaturated fatty acid b. three fatty acid molecules, all pointing in different directions c. two fatty acid molecules pointing in different directions d. a charged or polar end and an uncharged or nonpolar end e. two charged or polar ends | 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. | 81 | |
| 2204836829 | Which of the following is a true statement comparing phospholipids and triacylglycerols (fats and oils)? a. In nature, phospholipids occur in fused rings (sterol form), whereas triacylglycerols maintain a straight-chain form. b. Phospholipid molecules have a distinctly polar "head" and a distinctly nonpolar "tail," whereas triacylglycerols are predominantly nonpolar. c. Triacylglycerols may be saturated or unsaturated, but all phospholipids are saturated. d. Phospholipids are the primary storage form for fats in our bodies. e. 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. | 82 | |
| 2204836830 | The sex hormones estradiol and testosterone belong to which class of molecules? a. lipids b. proteins c. carbohydrates d. nucleic acids e. amino acids | lipids Steroids, such as estradiol and testosterone, are lipids based on their insolubility in water. The molecules are characterized by a carbon skeleton consisting of four fused rings of carbon atoms. | 83 | |
| 2204836831 | 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? a. Cholesterol is an important constituent of nucleotides. b. Cholesterol is an important energy storage molecule. c. Cholesterol aids in the formation of amino acids that are used to build proteins. d. Cholesterol is the precursor for many important molecules such as sex hormones. e. Cholesterol is not important for humans anymore. It is a holdover from hunter-gatherer days when food was scarce. | Cholesterol is the precursor for many important molecules such as sex hormones. Cholesterol is the basis for many steroid molecules, including sex hormones. | 84 | |
| 2204836832 | Manufacturers make vegetable oils solid or semisolid at room temperature by __________. a. adding hydrogen atoms to the single-bonded carbon atoms of the fatty acid hydrocarbon chains b. removing hydrogen atoms and forming additional single bonds in the fatty acid hydrocarbon chains c. removing hydrogen atoms and forming additional double bonds in the fatty acid hydrocarbon chains d. adding hydrogen atoms to the fatty acid hydrocarbon chains, thereby converting carbon-carbon double bonds to single bonds e. 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. | 85 | |
| 2204836833 | Which of the following is the major energy storage compound of plant seeds? a. cellulose b. oils c. amylose d. lipids e. glycogen | oils Vegetable oils are generally obtained from seeds, in which lighter weight makes dispersal easier. | 86 | |
| 2204836834 | Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by __________. a. glycosidic linkages b. phosphodiester linkages c. ester linkages d. ionic bonds e. peptide bonds | ester 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. | 87 | |
| 2204836835 | The fatty acid tails of a phospholipid are __________ because they __________. a. hydrophobic ... consist of units assembled by dehydration reactions b. hydrophilic ... are easily hydrolyzed into their monomers c. hydrophobic ... have no charges to which water molecules can adhere d. hydrophilic ... consist of units assembled by dehydration reactions e. hydrophobic ... dissolve easily in water | hydrophobic ... have no charges to which water molecules can adhere Phospholipid tails, which consist of nonpolar hydrocarbon chains, are hydrophobic. | 88 | |
| 2204836836 | The overall three-dimensional shape of a single polypeptide is called its __________. a. secondary structure b. tertiary structure c. primary structure d. double helix e. quaternary 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. | 89 | |
| 2204836837 | When a protein is denatured, why does it lose its functionality? a. The protein's pH changes, and the change causes the protein to lose its functionality. b. Different amino acids are substituted into the sequence, so the protein's properties change. c. 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. d. Denaturation destroys the primary structure of the protein, and the protein breaks down to monomers. e. 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. | 90 | |
| 2204836838 | Which of the following lists ranks these molecules in the correct order by size from smallest to largest? a. water, glucose, sucrose, protein b. water, sucrose, glucose, protein c. glucose, water, sucrose, protein d. water, protein, sucrose, glucose e. protein, water, glucose, sucrose | water, glucose, sucrose, protein In this case, the ranking is from smallest to largest. | 91 | |
| 2204836839 | Which of the following represents a specific description of a polypeptide? a. carbohydrates with a hydrogen bond holding them together b. organic monomers covalently bonded c. organic molecules linked by dehydration reactions d. amino acids linked by hydrolysis e. 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. | 92 | |
| 2204836840 | Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein? a. denaturing the protein b. a change in salt concentrations or pH c. treating the protein with a chemical that breaks hydrogen bonds d. heating the protein e. 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. | 93 | |
| 2204836841 | The α helix and β pleated sheet represent which level of protein structure? a. tertiary structure b. pentiary structure c. secondary structure d. quaternary structure e. primary structure | secondary structure Both the α helix and the β pleated sheet are localized regions of polypeptides held in a given structure by hydrogen bonds. | 94 | |
| 2204836842 | The peptide bond is __________. a. a covalent bond joining simple sugars together to form a polypeptide b. a covalent bond joining nucleotides together to form a nucleic acid c. a hydrogen bond joining nucleotides together to form a nucleic acid d. a hydrogen bond joining amino acids together to form a polypeptide e. a covalent bond joining amino acids 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. | 95 | |
| 2204836843 | Protein molecules are polymers (chains) of __________. a. fatty acid molecules b. DNA molecules c. purines and pyrimidines d. sucrose molecules e. amino acid molecules | amino acid molecules Polymers of amino acids are called polypeptides. A protein consists of one or more polypeptides folded into specific conformations. | 96 | |
| 2204836844 | The "primary structure" of a protein refers to __________. a. interactions among the side chains or R groups of the amino acids b. the weak aggregation of two or more polypeptide chains into one functional macromolecule c. the sequence of amino acids along a polypeptide chain d. the α helix or β pleated sheets e. coiling due to hydrogen bonding between amino acids | the sequence of amino acids along a polypeptide chain The primary structure of a protein is its unique sequence of amino acids joined by peptide bonds. | 97 | |
| 2204836845 | Which type of protein shields a newly forming protein from cytoplasmic influences while it is folding into its functional form? a. receptor proteins b. fibrous proteins c. antibodies d. chaperonins e. enzymes | chaperonins Chaperonins shield proteins from "bad influences" (interactions with other molecules in the cytoplasm) while they are folding into their functional forms. | 98 | |
| 2204836846 | What do Alzheimer's, Parkinson's, and mad cow disease have in common? a. All cause the misfolding of nucleic acids. b. All are associated with the buildup of lipids in brain cells due to faulty lysosome activity. c. All are caused by the buildup of misfolded proteins in cells. d. All are associated with plaque buildup in arteries (atherosclerosis). e. 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. | 99 | |
| 2204836847 | A glucose molecule is to starch as __________. a. an amino acid is to a nucleic acid b. a nucleic acid is to a polypeptide c. a steroid is to a lipid d. a protein is to an amino acid e. a nucleotide is to a nucleic acid | 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. | 100 | |
| 2204836848 | A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture __________. a. fatty acids b. proteins c. DNA d. sucrose e. cellulose | DNA The backbone of a nucleic acid consists of alternating sugar and phosphate groups. | 101 | |
| 2204836849 | Based on complementary base pairing, you would expect the percentage of __________ to be equal to the percentage of __________. a. adenine ... guanine b. thymine ... cytosine c. thymine ... guanine d. adenine ... cytosine e. adenine ... thymine | adenine ... thymine Adenine and thymine form a complementary base pair. | 102 | |
| 2204836850 | Which of the following are pyrimidines found in the nucleic acid DNA? a. thymine and cytosine b. thymine and adenine c. uracil and guanine d. adenine and guanine e. guanine and cytosine | thymine and cytosine Thymine and cytosine are pyrimidines found in DNA. | 103 | |
| 2204836851 | Which of the following describes a difference between DNA and RNA? a. RNA molecules generally consist of a single polynucleotide chain, whereas DNA molecules generally consist of two polynucleotide chains organized into a double helix. b. Both molecules contain adenine, guanine and cytosine, but DNA also contains thymine and RNA also contains uracil. c. They contain different sugars. d. The first and second listed responses correctly describe differences between DNA and RNA. e. The first three listed responses correctly describe differences between DNA and RNA. | The first three listed responses correctly describe differences between DNA and RNA. The first three listed responses describe distinctions between DNA and RNA. | 104 | |
| 2204836852 | Which of the following lists represents the chemical components of a nucleotide? a. a nitrogenous base, a phosphate group, and a pentose sugar b. a nitrogenous base, an amino acid, and a pentose sugar c. a nitrogenous base, a fatty acid, and an amino acid d. a series of nitrogenous bases, a nucleic acid backbone, and a hexose sugar e. a nitrogenous base, an amino acid, and a phosphate group | 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. | 105 | |
| 2204836853 | Which of the following is true regarding complementary base pairing in DNA and RNA molecules? a. Complementary base pairing promotes an antiparallel orientation in the structure of DNA and RNA molecules. b. 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. c. 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. d. Complementary base pairing within single strands of DNA and RNA gives them particular three-dimensional structures that are necessary for their function. e. 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. | 106 | |
| 2204836854 | Which of the following categories includes all others in the list? a. disaccharide b. monosaccharide c. carbohydrate d. starch e. polysaccharide | carbohydrate | 107 | |
| 2204836855 | The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the a form. Which of the following could amylase break down? a. starch, amylopectin, and cellulose b. glycogen and cellulose c. starch and chitin d. glycogen, starch, and amylopectin e. cellulose and chitin | glycogen, starch, and amylopectin | 108 | |
| 2204836856 | Which of the following statements concerning unsaturated fats is true? a. They generally solidify at room temperature. b. They contain more hydrogen than do saturated fats having the same number of carbon atoms. c. They are more common in animals than in plants. d. They have double bonds in the carbon chains of their fatty acids. e. They have fewer fatty acid molecules per fat molecule. | They have double bonds in the carbon chains of their fatty acids. | 109 | |
| 2204836857 | The structural level of a protein least affected by a disruption in hydrogen bonding is the a. primary level. b. quaternary level. c. tertiary level d. secondary level. e. All structural levels are equally affected. | primary level. | 110 | |
| 2204836858 | Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes? a. The phosphodiester linkages of the polynucleotide backbone would be broken. b. The two strands of the double helix would separate. c. The pyrimidines would be separated from the deoxyribose sugars. d. The purines would be separated from the deoxyribose sugars. e. All bases would be separated from the deoxyribose sugars. | The phosphodiester linkages of the polynucleotide backbone would be broken. | 111 | |
| 2204836859 | The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions? a. C60H100O50 b. C60H111O51 c. C60H102O51 d. C6H12O6 e. C60H120O60 | C60H102O51 | 112 | |
| 2204836860 | Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA? a. 5′-GCGC-3′ with 5′-TATA-3′ b. 5′-ATGC-3′ with 5′-GCAT-3′ c. 5′-purine-pyrimidine-purine-pyrimidine-3′ with 3′-purine-pyrimidine-purine-pyrimidine-5′ d. 5′-AGCT-3′ with 5′-TCGA-3′ e. All of these pairs are correct. | 5′-ATGC-3′ with 5′-GCAT-3′ | 113 | |
| 2204836861 | Signal proteins | Signal proteins include hormonal proteins that help coordinate an organism's activities by acting as signals between cells. For example, insulin, a hormonal protein secreted by the pancreas, signals an animal's cells to take in and use sugar. The hormone receptor is also a protein. | 114 | |
| 2204836862 | Receptor molecules | Receptor molecules bind to signal molecules and can then emit second messengers which trigger changes inside a cell. Receptors are thus important links in the system of communication among cells. Some signal molecules, such as hormones, are also proteins. | 115 | |
| 2204836863 | Structural proteins | Structural proteins have many functions. Like tent poles and ropes, they shape cells and anchor cell parts. They may serve as tracks along which cell parts can move. They bind cells together, making organized units such as muscles, ligaments, and the tendons that bind muscles to bones. The silk of spiders and the hair of mammals are also structural proteins. | 116 | |
| 2204836864 | Sensory proteins | Sensory proteins detect environmental changes such as light, and respond by emitting or producing signals that call for a response | 117 | |
| 2204836865 | Transport proteins | Transport proteins carry molecules from place to place. The example shown here allows certain solute molecules to enter the cell. Hemoglobin is the transport protein that carries oxygen in the blood. | 118 | |
| 2204836866 | enzyme | An enzyme is a protein that changes the rate of a chemical reaction without itself being changed into a different molecule in the process. Enzymes promote and regulate virtually all chemical reactions in cells. | 119 | |
| 2204836867 | Storage proteins | Storage proteins stockpile building components that cells can use to make other proteins. Storage proteins in seeds provide raw materials used by the developing plant-- unless an animal eats them first! | 120 | |
| 2204836868 | Ovalbumin | Ovalbumin, the main substance in egg white, serves as a storage protein for developing chick embryos | 121 | |
| 2204836869 | Gene | Gene regulatory proteins bind to DNA in particular locations and control whether or not certain genes will be read. This allows cells to become specialized for different functions and respond to changes in their surroundings. | 122 | |
| 2204836870 | antibodies | The immune system makes defensive proteins called antibodies that bind to invaders (such as the virus shown here) and mark the foreign objects for destruction. | 123 | |
| 2204836871 | Most proteins are folded into a complex globular shape. Each protein molecule consists of one or more chains of amino acid monomers. ** | **The amino acids are linked by peptide bonds, so a protein polymer is often called a polypeptide. Because they are so complicated, proteins are usually described in terms of four levels of structure. | 124 | |
| 2204836872 | Secondary structure results from hydrogen bonding between atoms along the polypeptide backbone. Oxygen and nitrogen atoms along the backbone are highly electronegative, giving them partial negative charges, and leaving nearby hydrogen atoms with partial positive charges. ** | **These negatively and positively charged atoms are attracted to one another at regular intervals along the chain, causing parts of the protein to twist or fold back upon itself. | 125 | |
| 2204836873 | tertiary structure | Superimposed on primary and secondary structure is tertiary structure, irregular loops and folds that give the protein its overall three-dimensional shape.The irregular folding of tertiary structure results from interactions among the R groups of amino acids. | 126 | |
| 2204836874 | The irregular folding of tertiary structure results from interactions among the R groups of amino acids. Acidic and basic R groups ionize, and these positively and negatively charged groups may form ionic bonds. Polar forces also contribute to tertiary structure. ** | **Hydrophilic (polar) R groups may hydrogen bond with one another, or turn outward and hydrogen bond with the surrounding water. Hydrophobic (nonpolar) R groups cluster on the inside of the protein, away from water. Tertiary structure may be further stabilized by strong covalent bonds between sulfur atoms in certain R groups. | 127 | |
| 2204836875 | quaternary structure | Some proteins consist of two or more polypeptide chains. The fourth level of protein structure-- quaternary structure-- results from the combination of two or more polypeptide subunits. | 128 | |
| 2204836876 | DNA structure 1 | Cells make nucleic acid polymers by linking together four kinds of monomers called nucleotides. Each nucleotide consists of a sugar (deoxyribose in DNA), a phosphate group, and a nitrogen-containing base-- abbreviated G, A, C, or T. Like letters in a sentence, the sequence of nucleotides in a nucleic acid carries information. The DNA of every organism has a unique nucleotide sequence. | 129 | |
| 2204836877 | DNA structure 2 | DNA normally consists of two strands of nucleotides that twist around one another, forming the famous double helix. The strands are held together by hydrogen bonds between pairs of nitrogenous bases. The base A always pairs with T, and C always pairs with G. | 130 | |
| 2204836878 | RNA structure | This is a closeup view of an RNA polymer. RNA looks a lot like DNA, except it is typically single-stranded, contains a different sugar (called ribose), and has the base uracil (U) instead of thymine (T). RNA is copied from part of a DNA molecule, so it is shorter than DNA-- dozens to thousands of nucleotides. | 131 |
