Solution Manual For Campbell Biology, 9th Edition

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Notes to InstructorsChapter 2 The Chemical Context of LifeChapter 3 Water and the Fitness of the EnvironmentWhat is the focus of these activities?Living organisms function in the real world, so they are subject to all the laws of chemistryand physics. In addition, biological organisms and systems are variable. No two organisms areexactly alike, and no two systems are identical in form or function. As a result, our analysisof such systems tends to deal with statistical averages or probabilities. This means that it isdifficult to understand biological systems without having a good basic understanding ofchemistry, physics, and math (including probability and statistics).The vast majority of introductory biology students have studied inorganic chemistry in theirhigh school and first-year college chemistry courses. Many students compartmentalize theirknowledge, however. In some cases, the compartmentalization is so extreme that the studentsfeel uncomfortable dealing with chemical formulas and ideas outside of chemistry classes.Therefore, it is generally useful to review some of the basic ideas in chemistry and, at thesame time, demonstrate how they can be applied to understanding biological systems.What are the particular activities designed to do?Activity 2.1 A Quick Review of Elements and CompoundsThe questions in this activity are designed to help students review and understand:•atomic/molecular number, mass number, and atomic/molecular weight and howthey can be used to determine the reactivity of elements;•various types of chemical bonds and how they affect the structure and energeticsof molecules; and•the difference between a mole and a molar equivalent and how a knowledge ofthese can be used in biological applications.Activity 3.1 A Quick Review of the Properties of WaterThe questions in this activity are designed to help students review and understand theproperties of water and how they support life. Students are asked to review these keyproperties:•H2O molecules are cohesive; they form hydrogen bonds with each other.•H2O molecules are adhesive; they form hydrogen bonds with polar surfaces.•Water is a liquid at normal physiological (or body) temperatures.•Water has a high specific heat.•Water has a high heat of vaporization.•Water’s greatest density occurs at 4°C.Notes to Instructors1

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In addition, students review pH and how it is related to both the ionization constant ofpure water and the concentration of H+ions in a solution.What misconceptions or difficulties can these activities reveal?Activity 2.1Question 1: Many students don’t understand that nutrients for plants are inorganic andmost nutrients for animals (heterotrophs) are organic.Questions 2 and 3: Most students know how to balance a chemical equation. Fewerunderstand the relationship between molecules of a substance and moles of thatsubstance. Similarly, most students can recite what a mole is; however, the majority havenot thought about how that knowledge can be applied. Therefore, much of this firstactivity is devoted to making it clear that a balanced equation indicates not only thenumber of molecules required but also the number of moles required. It also explains whymoles can be substituted for molecules in such equations.Question 4: Some students have difficulty understanding that a solution’s concentrationor molarity does not change if you aliquot or subdivide the solution into smaller volumes.To test this, ask your students: “There is 10% sugar in this solution. If I pour half of itinto one beaker and the other half into another beaker, what percent sugar will I have ineach beaker?” More than half of the students will automatically answer 5%.Questions 5 and 6: These questions are designed to help students understand how aknowledge of balanced equations and molar equivalents can be useful in biology.Questions 7 and 8: The answers go into a little more detail than doesCampbell Biology,9th edition. Students obviously shouldn’t be asked to know the specific electronegativityof each of the elements. However, using concrete numbers may help students understandhow their electronegativity is related to the type of bonds formed between elements.Activity 3.1Most students have no difficulty stating the properties of water and the definition of pH.On the other hand, not all of them have a good understanding of how these properties arerelated to biological and other phenomena. Therefore, some questions ask students torelate pH values to actual concentrations of H+ions in solution and to relate the propertiesof water to common experiences they have had in class or in life.2Notes to Instructors

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AnswersActivity 2.1 A Quick Review of Elements and Compounds1.Table 2.1 (page 32) lists the chemical elements that occur naturally in the humanbody. Similar percentages of these elements are found in most living organisms.Activity 2.13a. In what abiotic(nonlife) chemicalforms are theseelements often foundin nature?These elements aremost commonly foundas CO2, N2, and O2inthe atmosphere and asH20, PO4, and Scompounds on Earth.b. In what chemicalform(s) do animalsneed to obtain theseelements?With the exception ofoxygen and water,animals obtain themajority of theseelements in the formof organic compounds.c. In what chemicalform(s) do plants needto obtain theseelements?Plants can obtain C asCO2, N as ammonia ornitrite or nitrates,phosphorus asphosphates, sulfur assulfides or sulfates,and so on. In otherwords, plants obtainthese elements asinorganic compounds.2.A chemical element cannot be broken down to other forms by chemical reactions.Each element has a specific number of protons, neutrons, and electrons.a.What is the name of the following element, and how many protons, neutrons, andelectrons does it have?Na1123NameSodiumNumber of protons11Number of electrons11Number of neutrons12

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c.How would you determine how many grams are in a mole of any chemicalelement or compound?A mole of any chemical element or compound is equal to the mass number ingrams of that mole or compound. For example, the mass number of Na is 23;therefore, a mole of Na has a mass of 23 g. The mass number of water is 18;therefore, a mole of water has a mass of 18 g.4.One atom of Na can combine with one atom of Cl (chlorine) to produce onemolecule of NaCl (table salt).4Activity 2.1b.What information do you need to calculate or determine the following?The atomic number of anelementThe atomic number isequal to the number ofprotons (or electrons).The mass number of anelementThe mass number is equalto the number of protonsplus the number ofneutrons.The weight in daltons ofone atom of an elementYou can estimate theweight in daltons as 1dalton per proton orneutron.Therefore, theweight in daltons of anelement is approximatelyequal to the number ofprotons plus the numberof neutrons.c.What are the atomic number, mass number, and weight in daltons of the elementshown in part a?3.One mole of an element or compound contains 6.021023atoms or molecules ofthe element or compound. One mole of an element or compound has a mass equalto its mass number (or molecular weight) in grams. For example, 1 mole of hydrogengas (H2) contains 6.021023molecules and weighs 2 g.Atomic numberMass numberWeight in daltons112323a. What is the weight of 1 mole of puresodium (Na)?23 gb. How many molecules of Na are in1 mole of Na?6.021023a. If Cl has 17 electrons, 17protons, and 18 neutrons,what is its mass number?35b. What is the mass numberof NaCl?23 + 35 = 58c. How many grams ofNaCl equal a mole ofNaCl?58 g

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d. If you wanted to combine equal numbers of Na and Cl atoms in a flask, howmuch Cl would you have to add if you added 23 g of Na? (Include an explanationof the reasoning behind your answer.)23 g of Na is equal to 1 mole of Na. A mole contains 6.021023moleculesof the substance. To add an equal number of molecules of Cl, you need to add1 mole of Cl, or 35 g.e.To make a one-molar (1M) solution of NaCl, you need to add 1 mol of NaCl todistilled water to make a final volume of 1 L (1,000 ml). A 1Msolution is said tohave a molarity of 1. If you added 2 moles of NaCl to 1 L of distilled water,you would make a 2Msolution and its molarity would equal 2. You make upa 1Msolution of NaCl.Activity 2.155.The summary formula for photosynthesis is6 CO2+ 6 H2O→C6H12O6+ 6 O2How many molecules of NaCl are in the1MNaCl solution?If you used 1 L of water to make the 1Msolution, you would have 6.021023molecules in the liter.How many molecules of NaCl are thereper ml of the solution?To calculate the number of moleculesper ml, divide 6.021023by 1,000 =6.021020molecules/ml.f.Next, you divide this 1Msolution of NaCl into four separate flasks, putting250 mL into each flask.How many gramsof NaCl are in eachflask?58/4 = 14.5 gHow manymolecules of NaClare in each flask?6.021023divided by 4 =1.511023How manymolecules of NaClare there per ml ofdistilled water?6.021020What is themolarity of NaCl ineach of the fourflasks?1Ma. How many molecules of carbon dioxideand water would a plant have to use toproduce three molecules of glucose(C6H12O6)?For each molecule of glucose produced,6 molecules of carbon dioxide and6 molecules of water are consumed.Therefore, the plant would need to use18 molecules of each.b. How many moles of carbon dioxide andwater would a plant have to use toproduce 2 mole of glucose?Because a mole of anything contains thesame number of molecules, the plantwould need to use 6 times as many molesof carbon dioxide and water, or 12 molesof each.

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c.Refer to the summary formula for photosynthesis. If you know the number ofmolecules or moles of any of the reactants used (or products produced), howwould you calculate the number of molecules or moles of all of the otherreactants needed and products produced?If the formula is balanced and if it is a true representation of the overall reactionsthat occur, then the numbers in front of each reactant and product indicate themolecular or molar equivalents required for the reactions.Note:To represent the actual reactants required and products produced, theoverall formula for photosynthesis is more correctly stated as:6 CO2+ 12 H2O→C6H12O6+ 6 O2+ 6 H2OIn most texts, however, this is reduced to 6 CO2+ 6 H2O→C6H12O6+ 6 O26.A biologist places a plant in a closed chamber. A sensor in the chamber maintainsthe carbon dioxide level at the normal atmospheric concentration of 0.03%. Anothersensor allows the biologist to measure the amount of oxygen produced by the plantover time. If the plant produces 0.001 mole of oxygen in an hour, how much carbondioxide had to be added to the chamber during that hour to maintain the atmosphericconcentration of 0.03%?For every mole of oxygen produced, 1 mole of carbon dioxide had to be consumed.Therefore, 0.001 mole of carbon dioxide had to be added to maintain a constantlevel of CO2in the chamber.7.O2and NH3are both small covalent molecules found in cells. NH3is extremelysoluble in the aqueous environment of the cell, while O2is relatively insoluble. Whatis the basis for this difference in solubility between the two molecules? In reachingyour answer, draw the structures of the molecules as valence shell diagrams (as inFigure 2.12, page 38). Given these diagrams, consider the types of interactions eachmolecule could have with water.6Activity 2.1HHHNOOAmmonia is a polar molecule much like water. The N in it is relatively negative, andthe H’s are relatively positive. Polar substances tend to be more soluble in water. O2,on the other hand, is not polar.Ammonia (NH3)Oxygen (O2)

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8.Refer to pages 38–41 ofCampbell Biology, 9th edition, which describe these typesof chemical bonds: nonpolar and polar covalent bonds, ionic bonds, hydrogen bonds,and van der Waals interactions.The molecule diagrammed here can also be represented by the formula CH3COOH.Activity 2.17HHCCOOHHExplain how you could determine which of the bonds between elements in thismolecule are polar or nonpolar covalent bonds, ionic bonds, hydrogen bonds, andvan der Waals interactions.The best way to determine the bond types is to determine each atom’selectronegativity, or its attraction for electrons. As a general rule, the more filled theouter electron shell of an atom is, the higher is its electronegativity. In addition, thefewer electron shells, the greater the electron negativity. As a result, an atom’sattraction for electrons increases as you go from left to right in the periodic table.Electronegativity values tend to decrease as you go from top to bottom of theperiodic table. To determine whether bonds are ionic, polar covalent, or nonpolarcovalent, you need to determine the difference in electronegativity between theatoms that make up a molecule. If the difference in electronegativity is small, thebond is likely to be nonpolar covalent. If the difference is very large, the bond islikely to be ionic. Intermediate differences produce polar covalent bonds. Thefollowing table lists specific electronegativity values for selected elements.Using specific electronegativity values, you can determine the type of bond: If thedifference in electronegativity between two atoms in a compound is less than 0.5, thebond is nonpolar covalent. If the difference is between 0.5 and 1.6, the bond is polarcovalent. If the difference is greater than 1.6, the bond is ionic.H = 2.1Li = 1.0Be = 1.5B = 2.0C = 2.5N = 3.0O = 3.5F = 4.0Na = 0.9Mg = 1.2Al = 1.5Si = 1.8P = 2.1S = 2.5Cl = 3.0

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Activity 3.1 A Quick Review of the Properties of Water1.Compounds that have the capacity to form hydrogen bonds with water are said tobe hydrophilic (water loving). Those without this capacity are hydrophobic (waterfearing).8Activity 3.1Is the molecule on the left hydrophilic orhydrophobic? Explain your answer.This molecule is acetic acid. TheCOOH group ispolar, which makes this molecule hydrophilic.2.In addition to being polar, water molecules can dissociate into hydronium ions(H3O+, often described simply as H+) and hydroxide ions (OH). The concentrationof each of these ions in pure water is 107. Another way to say this is that theconcentration of hydronium ions, or H+ions, is one out of every 10 millionmolecules. Similarly, the concentration of OHions is one in 10 million molecules.a.The H+ion concentration of a solution can be represented as its pH value. ThepH of a solution is defined as the negative log10of the hydrogen ionconcentration.What is the pH of pure water?The hydrogen ion concentration of pure water is 107. The log10of 107is7.The negative log10of 107is therefore +7.b.Refer to the diagram of the molecule of acetic acid in question 1. The COOHgroup can ionize to release a H+ion into solution. If you add acetic acid to waterand raise the concentration of H+ions to 104, what is the pH of this solution?The pH of a solution with a H+ion concentration of 104is 4.3.Life as we know it could not exist without water. All the chemical reactions of lifeoccur in aqueous solution. Water molecules are polar and are capable of forminghydrogen bonds with other polar or charged molecules. As a result, water has thefollowing properties:A.H2O molecules are cohesive; they form hydrogen bonds with each other.B.H2O molecules are adhesive; they form hydrogen bonds with polar surfaces.C.Water is a liquid at normal physiological (or body) temperatures.D.Water has a high specific heat.E.Water has a high heat of vaporization.F.Water’s greatest density occurs at 4°C.HHCCOOHH

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Explain how these properties of water are related to the phenomena described inparts a–h below. More than one property may be used to explain a given phenomenon.a.During the winter, air temperatures in the northern United States can remainbelow 0°C for months; however, the fish and other animals living in the lakessurvive.Water’s greatest density occurs at 4°C. In a lake, the 4°C water sinks below thewater that is colder (or warmer). As a result, 0°C water is less dense than 4°C water.In addition, as it freezes, water takes on a crystalline structure and becomes ice.Ice has a density of about 0.92 g/cm3, pure water at 0°C has a density of about0.99 g/cm3, and pure water at 4°C has a density of 1.0 g/cm3. The ice on top of alake acts like insulation and, as a result, most deep lakes do not freeze to thebottom.b.Many substances—for example, salt (NaCl) and sucrose—dissolve quickly in water.Water is very polar. The attraction of the polar water molecules for the Na+andClions of NaCl is strong enough to allow them to dissociate and interact withwater molecules (dissolve).c.When you pour water into a 25-mL graduated cylinder, a meniscus forms at thetop of the water column.Water is attracted to the polar molecules that make up the glass (or plastic)cylinder. At the same time, they are attracted to each other. As a result, some ofthe water molecules associate with the polar molecules of the cylinder and areapparently “pulled up” the inside edge of the cylinder.d. Sweating and the evaporation of sweat from the body surface help reduce ahuman’s body temperature.Water has a high specific heat. The specific heat of water is 1 cal/g/°C. In otherwords, it takes 1 calorie of heat to change the temperature of 1 g of water 1°C. Inaddition, water has a high latent heat of vaporization (540 cal/g at 100°C). This canbe thought of as the additional heat required to break apart polar water moleculesso that they can move from the liquid to the gaseous state. As a result, evaporation(change of water from liquid to gaseous state) carries with it large amounts of heat.e.A bottle contains a liquid mixture of equal parts water and mineral oil. You shakethe bottle vigorously and then set it on the table. Although the law of entropyfavors maximum randomness, this mixture separates into layers of oil over water.The oil molecules are nonpolar and hydrophobic. The water molecules are polarand cohesive. As a result, the water molecules tend to interact strongly with eachother and exclude the oil molecules. The oil layers on top of the water because itis less dense than water.Activity 3.19

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f.Water drops that fall on a surface tend to form rounded drops or beads.Water molecules are cohesive and form hydrogen bonds with each other. As aresult, a drop of water tends to bead up or become rounded.g. Water drops that fall on your car tend to bead or round up more after you polish(or wax) the car than before you polished it.The wax (or polish) is hydrophobic and therefore less polar than the surface waslikely to be before you polished it. Because the adhesion between the surface andthe water molecules is lower, the cohesion of the water molecules for each otherappears even more dramatic.h. If you touch the edge of a paper towel to a drop of colored water, the water willmove up into (or be absorbed by) the towel.The polar water molecules adhere to the cellulose in the paper towel and cohereto each other. As a result, they are drawn up into the towel. The same mechanismaccounts for the movement of water molecules up capillary tubes.10Activity 3.1

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Notes to InstructorsChapter 4 Carbon and the Molecular Diversity of LifeChapter 5 The Structure and Function of MacromoleculesWhat is the focus of these activities?The activities associated with Chapters 2 and 3 provided students with a review of some ofthe basics of inorganic chemistry. The activities associated with Chapters 4 and 5 deal withorganic chemistry and biochemistry. Although most introductory biology students havehad some exposure to inorganic chemistry, fewer have had courses in organic chemistry orbiochemistry. Therefore, these activities are designed with these goals in mind:•Help students identify the major differences among the four main types ofbiological macromolecules: carbohydrates, lipids, proteins, and nucleic acids.•Recognize what functional groups are and how they can modify the generalproperties and functions of organic compounds.•Use their understanding from the goals above to predict how various structuralmodifications can affect the behavior of macromolecules.What are the particular activities designed to do?Activity 4.1/5.1 How can you identify organic macromolecules?This activity is designed to help students easily recognize carbohydrates, lipids, proteins,and nucleic acids when viewed as chemical structures. Students develop some simplerules to make it easier for them to recognize differences among the general chemicalstructures of carbohydrates, lipids, proteins, and nucleic acids. This type of activity isespecially important for the many introductory biology students who have not yet hadorganic chemistry or biochemistry.Activity 4.2/5.2 What predictions can you make about the behavior of organicmacromolecules if you know their structure?In this activity, students examine the general properties of organic macromolecules. Inparticular, they examine the properties of functional groups and how these can modify thebehavior of macromolecules. This includes how modifying functional groups can affectthe water solubility and the chemical reactivity of molecules.At the end of this activity, students are asked to predict how various macromoleculescould react if placed in specific environments or if modified in specific ways. Answeringthese questions requires students to integrate and use understanding they have gainedfrom Chapters 2–5.Notes to Instructors11

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What misconceptions or difficulties can these activities reveal?Activity 4.1/5.1Question 1, Part A: This question asks for the C:H:O ratio of the variousmacromolecules. For carbohydrates, it is approximately 1:2:1. For many lipids, it isapproximately 1:2:very few. And for proteins and nucleic acids, there is no reliable ratioof C:H:O. Many students become upset that the answer for proteins and nucleic acids is“no reliable ratio of C:H:O.” Remind them that they would not have known the C:H:Oratio was not a good predictor for these molecules unless they investigated it. Answerslike this just mean we need to look for other ways of identifying these molecules. Someof these other ways include looking for specific functional groups, for example amino andcarboxyl groups in amino acids and ribose versus deoxyribose and specific nucleotides toidentify RNA versus DNA.Part B: After developing their own rules for identifying macromolecules, most studentswon’t have difficulty identifying these structures as carbohydrate, protein, lipid, ornucleic acid. It is best to present this activity in that light; that is, let students know thatthe purpose of the activity is to help them prove it is possible to categorize complexmacromolecules using only a few simple rules.Activity 4.2/5.2Question 1: The table asks students to look at different possible characteristics of Rgroups.12Notes to InstructorsThis question helps students understand, for example, that something that is polar is alsohydrophilic; that is, these designations are not mutually exclusive. In addition, bylearning the characteristics of key functional groups, students will have a betterunderstanding of how modifications in macromolecular structure can lead tomodifications in function.Question 4: The first three experiments ask students to examine how phospholipids (andglucose) will distribute themselves in different kinds of aqueous environments. Manystudents have memorized that phospholipids can form bilayers or micelles in aqueousenvironments, and they have the misconception that phospholipids will organize intomicelles or bilayers under any circumstance.R groupBasic, acidic, orneutralPolar or nonpolarHydrophilic orhydrophobic

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AnswersActivity 4.1/5.1 How can you identify organic macromolecules?Refer to the figure (Some Simple Chemistry) on the next page when doing this activity.Part A. Answer the questions. Then use your answers to develop simple rules foridentifying carbohydrates, lipids, proteins, and nucleic acids.1.What is the approximate C:H:O ratio in each of the following types ofmacromolecules?Activity 4.1/5.113Carbohydrates1:2:1Lipids1:2:very fewProteinsThere is no reliableC:H:O ratio forproteins.Nucleic acidsThere is no reliableC:H:O ratio fornucleic acids.2.Which of the compounds listed in question 1 can often be composed of C, H, and Oalone?Carbohydrates and lipids can often be composed of C, H, and O alone.3.Which of the compounds can be identified by looking at the C:H:O ratios alone?Only carbohydrates and some lipids can be identified using C:H:O ratios alone.4.What other elements are commonly associated with each of these four types ofmacromolecules?CarbohydratesLipidsProteinsNucleic acidsAlways contain PNoNo (except forphospholipids)NoYesGenerally containno P*YesYes (except forphospholipids)YesNoAlways contain NNoNoYesYesGenerally containno NYesYesNoNoFrequentlycontain SNoNoYesNoGenerally containno SYesYesNoYes*Note:It is possible to find some exceptions in each of these categories where “Yes” isthe answer to “Generally contain no ___.” For example, in reaction sequences manycompounds undergo phosphorylation. However, if the natural state of the compounddoes not contain P (for example) the answer to “Generally contain no P” would be yes.

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14Activity 4.1/5.1Lipids:HCC(CH2)nCH2OHHOHOHCOCCCCOOHHHOOHHHHHOHHOHOHCOHCH3CH3CH3C(CH2)nCH3Fats, oils,waxes,cholesterolProteins:Enzymes,structuralproteinsSugars, starches,glycogen,celluloseCarbohydrates:CompoundSome Simple ChemistryBasiccomponentsReactionCC(CH2)nOOHHHOOCOHC(CH2)nCH3ProductHGlycerol+3 fatty acidsTriglyceride or fatDisaccharide6C hexosedehydrationreactionaminogroupcarboxylgroup(etc.)CC(CH2)nOOHHHOORHCCOOHH2NRHHHOHOCCH2NORHOHCCNHCOHC(CH2)n+ 3 H2OCH3dehydrationreactiondehydrationreaction+ 1 H2ODipeptide+ 1 H2O3 H2OH2OCH2OHHOHCOCCCCCH2OHCOCCCCCH2OHHHOOCH2OHOH2OPO4++++Base(Base = A, U, G, or C)RiboseRNADNADeoxyriboseBase(Base = A, T, G, or C)PO4peptidebondhydrogenbondsRHCH2NPPBSPBSPBS(etc.)(etc.)PPPPPBSPBSPBBBBSSSSOCRHOOHCCNHAmino acidNucleic acids:DNA,RNAHOCH2H HH12345HOCH25HOCCCCOHOHOHH HH1234HOCCCCOHOHH

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5.Functional groups can modify the properties of organic molecules. In the followingtable, indicate whether each functional group is polar or nonpolar and hydrophobicor hydrophilic. Which of these functional groups are found in proteins and lipids?Activity 4.1/5.115FunctionalgroupPolar ornonpolarHydrophobicor hydrophilicFound in allproteinsFound inmany proteinsFound inmany lipids—OHPolarHydrophilicNoIn some RgroupsIn fatty acidsas terminalreactive group—CH2NonpolarHydrophobicNoYes in sidegroupsYes—COOHPolarHydrophilicYesNo—NH2PolarHydrophilicYesNo—SHPolarHydrophilicNoNo Found incysteineNo—PO4PolarHydrophilicNoOnly if theyhave beenphosphorylatedInphospholipids6.You want to use a radioactive tracer that will label only the protein in an RNA virus.Assume the virus is composed of only a protein coat and an RNA core. Which of thefollowing would you use? Be sure to explain your answer.a. Radioactive Pb. Radioactive Nc. Radioactive Sd. Radioactive CTo distinguish between protein and RNA in a virus, you could use radioactivelylabeled S compounds. If you grew viruses on cells with radioactively labeled Scompounds, the sulfhydryl groups in the virus’s protein would become labeled butthe RNA would not become labeled.7.Closely related macromolecules often have many characteristics in common. Forexample, they share many of the same chemical elements and functional groups.Therefore, to separate or distinguish closely related macromolecules, you need todetermine how they differ and then target or label that difference.a.What makes RNA different from DNA?RNA contains ribose sugar, whereas DNA contains deoxyribose sugar. In addition,RNA contains uracil and not thymine. DNA contains thymine but not uracil.b.If you wanted to use a radioactive or fluorescent tag to label only the RNA in a celland not the DNA, what compound(s) could you label that is/are specific for RNA?You could label either ribose or uracil.

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