Chapter 1 The Foundations of Biochemistry
Multiple Choice Questions 1. Cellular foundations
Pages: 2– 2–4 iffi fficulty: 1 !ns: C In a bacterial cell, the DNA is in the:
A) B) C) D) E)
cell cell enve envelo lope pe.. cel cell mem memb brane rane.. nucleoid. nucleus. ribosomes.
2. Cellular foundations
Page: " ifficulty: 1 !ns: # A major change occurring in the evolution o eu!ar"otes rom pro!ar"otes #as the development o:
A) B) C) D) E)
DNA. photos photos"n "nthe thetic tic capabi capabilit lit" ". plas plasm ma mem membr bran anes es.. ribosomes. the nu nucleus.
3. Cellular foundations
Page: " ifficulty: 1 !ns: B In eu!ar"otes, the nucleus is enclosed b" a double membrane called the:
A) B) C) D) E)
cell cell membr embran ane. e. nucl nuclea earr env envel elop ope. e. nucleolus. nucl nucleo eop plasm lasm.. nucleosome ome.
4. Cellular foundations
Page: 4 ifficulty: 1 !ns: C $he dimensions o living cells are limited, on the lo#er end b" the minimum number o biomolecules necessar" or unction, and on the upper end b" the rate o diusion o solutes such as o%"gen. E%cept or highl" elongated cells, the" usuall" have lengths and diameters in the range o:
A) B) C) D) E)
&.' µm to '& µm. &.( µm to (& µm. &.( µm to '&& µm. ' µm to '&& µm. ' µm to (&& µm.
Chapter 1 The Foundations of Biochemistry
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5. Cellular foundations
Page: 4 ifficulty: 2 !ns: B hich group o single*celled microorganisms has man" members ound gro#ing in e%treme environments+
A) B) C) D) E)
Bacteria Archaea Eu!ar"otes eterotrophs None o the above
6. Cellular foundations
Page: $ ifficulty: 2 !ns: B $he bacterium E. coli re-uires simple organic molecules or gro#th and energ"it is thereore a:
A) B) C) D) E)
chemoautotroph. chemoheterotroph. lithotroph. photoautotroph. photoheterotroph.
7. Cellular foundations
Page: % ifficulty: 1 !ns: hich is a list o organelles+
A) B) C) D) E)
/itochondria, chromatin, endoplasmic reticulum 0ero%isomes, l"sosomes, plasma membrane 0roteasomes, pero%isomes, l"sosomes /itochondria, endoplasmic reticulum, pero%isomes All o the above
8. Cellular foundations
Pages: %–& ifficulty: 2 !ns: B hich one o the ollo#ing has the cellular components arranged in order o increasing si1e+
A) B) C) D) E)
Amino acid 2 protein 2 mitochondrion 2 ribosome Amino acid 2 protein 2 ribosome 2 mitochondrion Amino acid 2 ribosome 2 protein 2 mitochondrion 0rotein 2 amino acid 2 mitochondrion 2 ribosome 0rotein 2 ribosome 2 mitochondrion 2 amino acid
9. Cellular foundations
Page: 1' ifficulty: 2 !ns: ! $he three*dimensional structure o macromolecules is ormed and maintained primaril" through noncovalent interactions. hich one o the ollo#ing is not considered a noncovalent interaction+
A) Carbon*carbon bonds B) "drogen bonds C) "drophobic interactions
Chapter 1 The Foundations of Biochemistry
D) Ionic interactions E) van der aals interactions 10.
Chemical foundations Page: 11 ifficulty: 2 !ns: # hich one o the ollo#ing is not among the our most abundant elements in living organisms+
A) B) C) D) E)
Carbon "drogen Nitrogen 3%"gen 0hosphorus
11.
Chemical foundations Pages: 12–1" ifficulty: 1 !ns: B $he our covalent bonds in methane 4C 5) are arranged around carbon to give #hich one o the ollo#ing geometries+
A) B) C) D) E)
Linear $etrahedral $rigonal bip"ramidal
Trigonal planar $rigonal p"ramidal
12.
Chemical foundations Page: 12 ifficulty: 1 !ns: B hat unctional groups are present on this molecule+
A) B) C) D) E)
Ether and aldeh"de "dro%"l and aldeh"de "dro%"l and carbo%"lic acid "dro%"l and ester "dro%"l and !etone
13.
Chemical foundations Page: 14 ifficulty: 1 !ns: $he macromolecules that serve in the storage and transmission o genetic inormation are:
A) B) C) D) E)
carboh"drates. lipids. membranes. nucleic acids. proteins.
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Chapter 1 The Foundations of Biochemistry
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14.
Chemical foundations Page: 1% ifficulty: 1 !ns: 6tereoisomers that are nonsuperimposable mirror images o each other are !no#n as:
A) B) C) D) E)
anomers. cis*trans isomers. diastereoisomers. enantiomers. geometric isomers.
15.
Chemical Foundations Page: 1$ ifficulty: 1 !(): $he catalog o all proteins unctioning in a cell is the:
A) B) C) D) E)
metabolome. proteasome. l"sosome. proteome. genome.
16.
Chemical foundations Page: 4 ifficulty: 2 !(): C 7se the terms a) chemoautotrophs, b) chemoheterotrophs, c) photoautotrophs, and d) photoheterotrophs and identi" the ans#er that correctl" inishes the statement: Carnivores are and herbivores are .
A) B) C) D) E)
b, c b, d b, b a, b a, a
17.
Chemical foundations Page: 1& ifficulty: " !ns: # $he en1"me umarase catal"1es the reversible h"dration o umaric acid to l*malate, but it #ill not catal"1e the h"dration o maleic acid, the cis isomer o umaric acid. $his is an e%ample o:
A) B) C) D) E)
biological activit". chiral activit". racemi1ation. stereoisomeri1ation. stereospeciicit".
18.
Physical foundations Page: 2' ifficulty: 2 !ns: ! umans maintain a nearl" constant level o hemoglobin b" continuall" s"nthesi1ing and degrading it. $his is an e%ample o a4n):
A) d"namic stead" state. B) e-uilibrium state. C) e%ergonic change.
Chapter 1 The Foundations of Biochemistry
D) ree*energ" change. E) #aste o energ". 19.
Physical foundations Page: 22 ifficulty: 1 !ns: C I heat energ" is absorbed b" the s"stem during a chemical reaction, the reaction is said to be:
A) B) C) D) E)
at e-uilibrium. endergonic. endothermic. e%ergonic. e%othermic.
20.
Physical foundations Page: 22 ifficulty: 2 !ns: I the ree energ" change ∆8 or a reaction is – 59.'' !;mol, the reaction is:
A) B) C) D) E)
at e-uilibrium. endergonic. endothermic. e%ergonic. e%othermic.
21.
Physical foundations Page: 2" ifficulty: 2 !ns: C $he major carrier o chemical energ" in all cells is:
A) acet"l triphosphate. B) adenosine monophosphate. C) adenosine triphosphate. D) c"tosine tetraphosphate. E) uridine diphosphate. 22.
Physical foundations Page: 2$ ifficulty: 2 !ns: ! En1"mes are biological catal"sts that enhance the rate o a reaction b":
A) B) C) D) E)
decreasing the activation energ". decreasing the amount o ree energ" released. increasing the activation energ". increasing the amount o ree energ" released. increasing the energ" o the transition state.
23.
Physical foundations Page: 2$ ifficulty: 1 !ns: B Energ" re-uiring metabolic path#a"s that "ield comple% molecules rom simpler precursors are:
A) amphibolic. B) anabolic. C) autotrophic.
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Chapter 1 The Foundations of Biochemistry
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D) catabolic. E) heterotrophic. 24* +enetic foundations Page: 2, ifficulty: 1 !ns: ! ereditar" inormation 4#ith the e%ception o some viruses) is preserved in:
A) B) C) D) E)
deo%"ribonucleic acid. membrane structures. nuclei. pol"saccharides. ribonucleic acid.
2$* +enetic foundations Page: 2& ifficulty: 2 !ns: C hen a region o DNA must be repaired b" removing and replacing some o the nucleotides, #hat ensures that the ne# nucleotides are in the correct se-uence+
A) B) C) D) E)
DNA cannot be repaired and this e%plains #h" mutations occur. 6peciic en1"mes bind the correct nucleotides. $he ne# nucleotides base pair accuratel" #ith those on the complementar" strand. $he repair en1"me recogni1es the removed nucleotide and brings in an identical one to replace it. $he three*dimensional structure determines the order o nucleotides.
2%* +enetic foundations Page: 2- ifficulty: 2 !ns: # $he three*dimensional structure o a protein is determined primaril" b":
A) B) C) D) E)
electrostatic guidance rom nucleic acid structure. ho# man" amino acids are in the protein. h"drophobic interaction #ith lipids that provide a olding rame#or!. modiication during interactions #ith ribosomes. the se-uence o amino acids in the protein.
2,* #.olutionary foundations Pages: "'–"1 ifficulty: 2 !ns: According to 3parin
A) B) C) D) E)
alread" contained some primitive =NA molecules. basicall" #as ver" similar to the atmosphere o toda". contained man" amino acids. had an abundance o methane, ammonia, and #ater. #as rich in o%"gen.
2&* #.olutionary foundations Page: "& ifficulty: 2 !(): # hen t#o genes in an organism share detectable se-uence similarit", those genes or their gene products, are said to be:
A) homologues.
Chapter 1 The Foundations of Biochemistry
B) C) D) E) >)
,
orthologues. paralogues. A and B. A and C. B and C
)hort !ns/er Questions 2-* Cellular foundations Pages: 1–2 ifficulty: 1 hat si% characteristics distinguish living organisms rom inanimate objects+ !ns: ?iving organisms 4') are chemicall" comple% and highl" organi1ed@ 4) e%tract, transorm, and use energ" rom their environment@ 4() have the capacit" to precisel" sel*replicate and sel*assemble@ 45) e%ploit a chemical interpla" #ith their environment@ 4) possess programmaticall" deined unctions@ and 49) evolve to ne# orms over man" generations. "'* Cellular foundations Page: " ifficulty: 1 All cells are surrounded b" a plasma membrane composed o lipid and protein molecules. hat is the unction o the plasma membrane+ !ns: $he plasma membrane acts as a barrier to the ree passage o inorganic ions and most other charged or polar compounds into or out o the cell. It contains proteins that can transport speciic ions or molecules. 3ther membrane proteins act as receptors that transmit signals rom the outside to the inside o the cell. "1* Cellular foundations Page: $ ifficulty: 1 E. coli is !no#n as a gram*negative bacterial species. 4a) o# is this determined+ 4b) o# do gram* negative bacteria dier structurall" rom gram*positive bacteria+ !ns: 4a) 8ram*negative bacteria have little ainit" or the d"e gentian violet used in 8rams stain, but gram*positive bacteria retain 8ramig. '*, p. 9.) ""* Cellular foundations Page: 1' ifficulty: 2 4a) ?ist the t"pes o noncovalent interactions that are important in providing stabilit" to the three* dimensional structures o macromolecules. 4b) h" is it important that these interactions be
Chapter 1 The Foundations of Biochemistry
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noncovalent, rather than covalent, bonds+ !ns: 4a) Noncovalent interactions include h"drogen bonds, ionic interactions bet#een charged groups, van der aals interactions, and h"drophobic interactions. 4b) Because noncovalent interactions are #ea!, the" can orm, brea!, and re*orm more rapidl" and #ith less energ" input than can covalent bonds. $his is important to maintain the le%ibilit" needed in macromolecules. "4* Cellular foundations Page: " ifficulty: 2 hat is the dierence, i an", bet#een c"tosol and c"toplasm+ !ns: $he c"toplasm is the internal volume enclosed b" the plasma membrane@ the c"tosol is the a-ueous portion o the c"toplasm. "$* Cellular foundations Page: % ifficulty: 2 0rovide a brie e%planation or the observation that macromolecules diuse at a slo#er rate in the c"tosol than the" do in dilute solution. !ns: $he c"tosol is ver" cro#ded and gel*li!e. $he diusion o macromolecules is slo#ed b" collisions #ith other large molecules and structures. "%* Chemical foundations Page: 12 ifficulty: 1 Dra# the structures o the ollo#ing unctional groups in their un*ioni1ed orms: 4a) h"dro%"l, 4b) carbo%"l, 4c) amino, 4d) phosphor"l. !ns:
",* Chemical foundations Pages: 1"–14 ifficulty: 2 hat is the underl"ing, organi1ing biochemical principle that results in the chemical similarit" o virtuall" all living things+ 8iven this biochemical similarit", ho# is the structural and unctional diversit" o living things possible+ !ns: ?iving things are composed primaril" o macromolecules, pol"mers o simple compounds o just a e# dierent t"pes. $he properties o these pol"mers are determined b" their se-uence o monomers and these can be combined in man" dierent #a"s. Diversit" is thus achieved through the nearl" limitless variet" o se-uences that can e%ist #hen amino acids are lin!ed to orm proteins, nucleotides are lin!ed to orm nucleic acids, and monosaccharides are lin!ed to orm pol"saccharides. Branching in the latter can contribute additional heterogeneit". Each t"pe o organism constructs a uni-ue set o macromolecules rom these monomeric units, resulting in the structural and unctional diversit" among species. "&* Chemical foundations
Chapter 1 The Foundations of Biochemistry
Page: 1$ ifficulty: 2 E%plain the dierence, i an", bet#een a proteome and a proteasome. !ns: A proteome is the list o all proteins that unction in a given cell. A proteasome is a molecular machine or supramolecular structure responsible or protein degradation in a cell.
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Chapter 1 The Foundations of Biochemistry
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"-* Chemical foundations Page: 14 ifficulty: 2 Name t#o unctions o 4a) proteins, 4b) nucleic acids, 4c) pol"saccharides, 4d) lipids. !ns: /an" ans#ers are possible including: 4a) proteins unction as en1"mes, structural elements, signal carriers, transporters@ 4b) nucleic acids store and transmit genetic inormation and act as both structural and catal"tic elements@ 4c) pol"saccharides serve as energ"*"ielding uel stores and cellular and e%tracellular structural and recognition elements@ 4d) lipids unction as membrane components, uel stores, and cellular signals. 4'* Chemical Foundations Page: 1% ifficulty: 2 h" is an as"mmetric carbon atom called a chiral center+ !ns: An as"mmetric carbon has our dierent substituents attached, and cannot be superimposed on its mirror imageas a right hand cannot it into a let glove. $hus, a molecule #ith one chiral carbon #ill have t#o stereoisomers, #hich ma" be distinguishable rom one another in a biological s"stem. 41* Chemical foundations Pages: 1$–1%0 1& ifficulty: " Dierentiate bet#een coniguration and conormation. !ns: Coniguration denotes the spatial arrangement o the atoms o a molecule that is conerred b" the presence o either double bonds, around #hich there is no reedom o rotation, or chiral centers, #hich give rise to stereoisomers. Conigurational isomers can onl" be interconverted b" temporaril" brea!ing covalent bonds. Conormation reers to the spatial arrangement o substituent groups that, #ithout brea!ing an" bonds, are ree to assume dierent positions in space because o the reedom o bond rotation. 42* Chemical foundations Pages: 1%–1, ifficulty: " 4a) hat is optical activit"+ 4b) o# did ?ouis 0asteur arrive at an e%planation or the phenomenon o optical activit"+ !ns: 4a) 3ptical activit" is the capacit" o a substance to rotate the plane o plane*polari1ed light. 4b) 7sing ine orceps, he #as able to separate the t#o t"pes o cr"stals ound in tartaric acid 4racemic acid) that are identical in shape, but mirror images o each other. 3ne sample rotated polari1ed light to the let@ the mirror image cr"stals rotated polari1ed light to the right. 4"* Chemical foundations Pages: 1&–1ifficulty: " A chemist #or!ing in a pharmaceutical lab s"nthesi1ed a ne# drug as a racemic mi%ture. h" is it important that she separate the t#o enantiomers and test each or its biological activit"+ !ns: Biomolecules such as receptors or drugs are stereospeciic, so each o the t#o enantiomers o the drug ma" have ver" dierent eects on an organism. 3ne ma" be beneicial, the other to%ic@ or one enantiomer ma" be ineective and its presence could reduce the eicac" o the other enantiomer. 44. Chemical foundations
Page: 1&
ifficulty: "
Chapter 1 The Foundations of Biochemistry
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E%plain #h" living organisms are able to produce particular chiral orms o dierent biomolceules #hile laborator" chemical s"nthesis usuall" produces a racemic mi%ture. !ns: ?aborator" s"ntheses usuall" use achiral reagents and thus produce racemic mi%tures o products. In contrast, because all en1"mes are made o chiral precursors, all en1"mes are inherentl" chiral catal"sts. $hus, the" #ill sho# strong stereoselectivit" in reactants and mechanisms, leading to the production o chiral products. 4$* Physical foundations Page: 2' ifficulty: 2 0roteins are constantl" being s"nthesi1ed in a living cell. h" doesnt the number o protein molecules become too great or the cell to contain, leading to cell destruction+ !ns: $he proteins in a cell are continuousl" being s"nthesi1ed and degraded. $he cell maintains a d"namic stead" state in #hich the amount o each protein remains airl" constant at the level re-uired under given conditions. 4%* Physical foundations Page: 2' ifficulty: 2 Describe the relationship bet#een a living organism and its surroundings in terms o both matter and energ". !ns: ?iving organisms are open s"stems and e%change both matter and energ" #ith their surroundings. $he" are not at e-uilibrium #ith their surroundings@ that is, the concentrations o molecules inside the cells o the organism are not the same as their concentrations in the surroundings. $o maintain this situation, the organism must ac-uire energ" rom its surroundings, either in the orm o chemical energ" or directl" rom sunlight. 4,* Physical foundations Pages: 22–24 ifficulty: 2 $he ree*energ" change or the ormation o a protein rom the individual amino acids is positive and is thus an endergonic reaction. o#, then, do cells accomplish this process+ !ns: $he endergonic 4thermod"namicall" unavorable) reaction is coupled to an e%ergonic 4thermod"namicall" avorable) reaction through a shared intermediate, so that the overall ree*energ" change o the coupled reactions is negative 4the overall reaction is e%ergonic). 4&* Physical foundations Pages: 22–24 ifficulty: " Instant cold pac!s get cold #hen the contents, usuall" solid urea and li-uid #ater, are mi%ed, producing an a-ueous solution o urea. Although this process is clearl" spontaneous, the products are colder than the reactants. E%plain ho# this is possible in terms o the dierence bet#een ∆8 and ∆. !ns: 6ince the dissolution reaction is spontaneous, the ∆8 must be negative. 6ince the reaction absorbs heat, the ∆ must be positive. 8iven ∆8 ∆ – $∆6, this is possible i the ∆6 is ver" large and positive, as one #ould e%pect or a solid dissolving.
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Chapter 1 The Foundations of Biochemistry
4-* Physical foundations Pages: 24–2$ ifficulty: 2 4a) 3n the reaction coordinate diagram sho#n belo#, label the transition state and the overall ree* energ" change 4∆8) or the uncatal"1ed reaction A → B. 4b) Is this an e%ergonic or endergonic reaction+ 4c) Dra# a second curve sho#ing the energetics o the reaction i it #ere en1"me* catal"1ed.
!ns: 4a) and 4c) 46ee >ig. '*, p. .) 4b) e%ergonic reaction $'* Physical foundations Page: 2% ifficulty: 2 hat is meant b" eedbac! inhibition and #h" is it important in a living organism+ !ns: >eedbac! inhibition is the regulation o a biochemical path#a" in #hich a reaction product inhibits an earlier 4usuall" the irst) step in the path#a". It is an important t"pe o regulation because it ensures that energ" is not #asted b" an organism producing molecules it does not need. $1* +enetic foundations Pages: 2,–2ifficulty: 2 o# is the genetic inormation encoded in DNA and ho# is a ne# cop" o DNA s"nthesi1ed+ !ns: $he genetic inormation is encoded in the linear se-uence 4order) o the our dierent deo%"ribonucleotides in the DNA. hen a ne# cop" o DNA is needed, the t#o strands o the DNA un#ind and each strand serves as a template on #hich a ne# strand is s"nthesi1ed. $2* +enetic foundations Pages: 2,–"' ifficulty: " ereditar" transmission o genetic inormation can be vie#ed as a balance bet#een stabilit" and change. E%plain. !ns: ereditar" transmission o genetic inormation occurs via replication o DNA, the inormation* containing molecule. $his process is ver" accurate and thus results in relativel" e# changes in genetic inormation. $his stabilit" is important to maintain individual and species characteristics over long periods o time. 3n the other hand, regular changes in genetic inormation 4mutations) do occur, primaril" as a result o inre-uent errors in replication. $hese mutations are essential or generating genetic diversit", #hich allo#s or adaptation o species.
Chapter 1 The Foundations of Biochemistry
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$"* +enetic foundations Pages: 2-–"' ifficulty: " Discuss ho# a mutation in DNA could be harmul or beneicial to an organism. !ns: 6ome mutations lead to the s"nthesis o an inactive or deective en1"me or other protein that can no longer carr" out its proper unction, #hich is thus harmul to the organism. o#ever, other mutations ma" lead to a more stable en1"me or to a protein that is better able to carr" out its unction in a particular environment, ma!ing it beneicial to the organism. $4* #.olutionary foundations Pages: "' F "1 ifficulty: " Describe 6tanle" /iller
$,* #.olutionary foundations Page: "" ifficulty: 2 hat is meant b" endos"mbiotic association+ o# can this concept e%plain the evolution o eu!ar"otic cells that are capable o carr"ing out photos"nthesis and;or aerobic metabolism+ !ns: An endos"mbiotic association is the envelopment o one organism b" another to orm a relationship that is beneicial to both organisms. It is believed that primitive eu!ar"otic cells, #hich #ere incapable o photos"nthesis or aerobic metabolism, ormed endos"mbiotic associations #ith photos"nthetic and;or aerobic bacteria. $he aerobic bacteria then evolved into the mitochondria ound in modern eu!ar"otic cells, and the photos"nthetic bacteria evolved into the chloroplasts ound in plant cells. 46ee >ig. '*(9, p. (.)
