Lehninger Principles of Biochemistry 6th Edition

*Significant figures: In multiplication and division, the answer can be expressed with nomore significant figures than the least precise value in the calculation. Because some of thedata in these problems are derived from measured values, we must round off the calculatedanswer to reflect this. In this first example, the radius

Chapter 1 The Foundations of Biochemistry Multiple Choice Questions 1. Cellular foundations Pages: 24 Difficulty: 1 Ans: C Pages: 24 Difficulty: 1 Ans: C Pages: 24 Difficulty: 1 Ans: C In a bacterial cell, the DNA is in the: A) cell envelope. B)

Answer The term lipid does not specify a particular chemical structure. Whereas one canwrite a general formula for an amino acid, nucleic acid, or protein, lipids are much morechemically diverse. Compounds are categorized as lipids based on their greater solubility inorganic solvents than in water. Answer The term lipid does not

Chapter 10 Lipids Multiple Choice Questions 1. Storage Lipids Pages: 357362 Difficulty: 2 Ans: E Pages: 357362 Difficulty: 2 Ans: E Pages: 357362 Difficulty: 2 Ans: E Which of the following molecules or substances contain, or are derived from, fatty acids? A)

Chapter 11 Biological Membranes and Transport Multiple Choice Questions 1. The composition and architecture of membranes Page: 386 Difficulty: 2 Ans: C Page: 386 Difficulty: 2 Ans: C Page: 386 Difficulty: 2 Ans: C Which one of the following statements about membranes is true?

S-120 Biological Membranes and Transport chapter 11 1. Determining the Cross-Sectional Area of a Lipid Molecule When phospholipids are layered gen- tly onto the surface of water, they orient at the air-water interface with their head groups in the water and their hydrophobic tails in the air. An experimental apparatus (a) has been devised that reduces

Chapter 12 Biosignaling Multiple Choice Questions 1. General Features of Signal Transduction Page: 436 Difficulty: 2 Ans: E Page: 436 Difficulty: 2 Ans: E Page: 436 Difficulty: 2 Ans: E Which of the following is not involved in the specificity of signal transduction?

S-131 S-131 S-131 Answer Substance X is cyclic AMP. Epinephrine stimulates glycogen phosphorylase byactivating the enzyme adenylyl cyclase, which catalyzes formation of cAMP, the secondmessenger.(a) Adenylyl cyclase is a membrane-bound protein; centrifugation sediments it into theparticulate fraction.(b) Cyclic AMP directly stimulates glycogen phosphorylase.(c) Cyclic AMP is heat-stable; it can be prepared by treating

Chapter 13 Principles of Bioenergetics Multiple Choice Questions 1. Bioenergetics and thermodynamics Page: 506 Difficulty: 1 Ans: E Page: 506 Difficulty: 1 Ans: E Page: 506 Difficulty: 1 Ans: E If the G' of the reaction A B is 40 kJ/mol, under standard conditions the

Answer Consider the developing chick as the system. The nutrients, egg shell, and outsideworld are the surroundings. Transformation of the single cell into a chick drastically reducesthe entropy of the system (increases the order). Initially, the parts of the egg outside the em-bryo (within the surroundings) contain complex fuel molecules

Chapter 14 Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway Multiple Choice Questions 1. Glycolysis Page: 544 Difficulty: 2 Ans: D Page: 544 Difficulty: 2 Ans: D Page: 544 Difficulty: 2 Ans: D Glycolysis is the name given to a metabolic pathway occurring in

Answer The initial phase of glycolysis requires ATP; it is endergonic. There are five reactionsin this phase:1. Glucose ATP 88n glucose 6-phosphate ADP G 16.7 kJ/mol2. Glucose 6-phosphate 88n fructose 6-phosphate G 1.7 kJ/mol3. Fructose 6-phosphate ATP 88n fructose 1,6-bisphosphate G 14.2 kJ/mol4. Fructose 1,6-bisphosphate 88ndihydroxyacetone phosphate glyceraldehyde 3-phosphate G

Answer(a) The mass-action ratio, Q0.0293(22.0 mM)(1,320 mM)(87.0 mM)(11,400 mM) Answer(a) The mass-action ratio, Q0.0293(22.0 mM)(1,320 mM)(87.0 mM)(11,400 mM) Answer (a) The mass-action ratio, Q0.0293 (22.0 m M )(1,320 m M ) (87.0 m M )(11,400 m M ) Principles of Metabolic Regulation chapter 15 S-173 1. Measurement of Intracellular Metabolite Concentrations Measuring the concentrations of metabolic intermediates in a living cell presents great experimental difficultiesusually a cell must be destroyed

Chapter 15 Principles of Metabolic Regulation Multiple Choice Questions 1. Which of the following does not contribute to the regulation of enzymatic activity? A) Protein phosphorylation B) Allosteric regulation C) Protein stability D) mRNA stability E) DNA stability Regulation of

S-183 S-183 S-183 Citrate synthase(a) Acetyl-CoA oxaloacetate H2O 88n citrate CoA(b) CoA(c) CondensationAconitase(a) Citrate 88n isocitrate(b) No cofactors(c) IsomerizationIsocitrate dehydrogenase(a) Isocitrate NAD88n a-ketoglutarate CO2NADH(b) NAD(c) Oxidative decarboxylationa-Ketoglutarate dehydrogenase(a) a-Ketoglutarate NADCoA 88n succinyl-CoA CO2NADH(b) NAD, CoA, thiamine pyrophosphate(c) Oxidative decarboxylationSuccinyl-CoA synthetase(a) Succinyl-CoA PiGDP 88n succinate CoA GTP(b) CoA(c) Substrate-level phosphorylation and acyl transfer Citrate synthase(a)

Chapter 16 The Citric Acid Cycle Multiple Choice Questions 1. Which of the following is not true of the reaction catalyzed by the pyruvate dehydrogenase complex? A) Biotin participates in the decarboxylation. B) Both NAD+ and a flavin nucleotide act as electron carriers.

S-199 S-199 S-199 Answer The fatty acids of triacylglycerols are hydrocarbons, with a single carboxyl group.Glycerol, on the other hand, has an OOH group on each carbon and is thus much more highlyoxidized than a fatty acid. On oxidation, fatty acids therefore produce far more energy percarbon than does glycerol. Triacylglycerols have an

Chapter 17 Fatty Acid Catabolism Multiple Choice Questions 1. Lipoprotein lipase acts in: A) hydrolysis of triacylglycerols of plasma lipoproteins to supply fatty acids to various tissues. B) intestinal uptake of dietary fat. C) intracellular lipid breakdown of lipoproteins. D) lipoprotein breakdown to

Chapter 18 Amino Acid Oxidation and the Production of Urea Multiple Choice Questions 1. Under which circumstances are amino acids not metabolized via oxidative degradation? A) Starvation B) Plants growing in nutrient-rich soils C) Normal protein turnover D) A diet rich in proteins

S-211 S-211 S-211 Answer Muscle tissue can convert amino acids to their keto acids plus ammonia, then oxidizethe keto acids to produce ATP for muscle contraction. However, urea cannot be formed in Answer Muscle tissue can convert amino acids to their keto acids plus ammonia, then oxidizethe keto acids to produce ATP for muscle

Chapter 19 Oxidative Phosphorylation and Photophosphorylation Multiple Choice Questions 1. Almost all of the oxygen (O2) one consumes in breathing is converted to: A) acetyl-CoA. B) carbon dioxide (CO2). C) carbon monoxide and then to carbon dioxide. D) None of the above E) water.

S-223 S-223 S-223 Answer Oxidation-reduction reactions require an electron donor and an electron acceptor.Recall that electron donors are reducing agents; electron acceptors are oxidizing agents.(1) NADH is the electron donor (a) and the reducing agent (d); E-FMN is the electron ac-ceptor (b) and the oxidizing agent (e); NAD/NADH and E-FMN/E-FMNH2are conjugate re-dox pairs

Chapter 19 Oxidative Phosphorylation and Photophosphorylation 231 Short Answer Questions 44. As you read and answer this question, you are (presumably) consuming oxygen. What single reaction accounts for most of your oxygen consumption? Ans: O2 is converted to H2O by electrons from the respiratory chain. The final

12 Chapter 2 Water Multiple Choice Questions 1. Weak interactions in aqueous systems Pages: 4345 Difficulty: 2 Ans: D Pages: 4345 Difficulty: 2 Ans: D Pages: 4345 Difficulty: 2 Ans: D Which of these statements about hydrogen bonds is not true? A) Hydrogen

Answer Ethanol is polar; ethane is not. The ethanol OH group can hydrogen-bond with water. Answer Ethanol is polar; ethane is not. The ethanol OH group can hydrogen-bond with water. Answer Ethanol is polar; ethane is not. The ethanol OH group can hydrogen-bond with water. Answer Using pH log [H]:(a) log (1.75 105)

Chapter 20 Carbohydrate Biosynthesis in Plants and Bacteria Multiple Choice Questions 1. Which of the following is not true about plastids? A) Most of the proteins in a plastid are encoded in nuclear genes. B) Plastids are encoded by a double membrane. C) Plastids

Answer Within organelles, reaction intermediates and enzymes can be maintained at differ-ent levels from those in the cytosol and in other organelles. For example, the ATP/ADP ratio islower in mitochondria than in the cytosol because the role of adenine nucleotides in themitochondrial matrix is to accept a phosphoryl group, whereas

S-247 S-247 S-247 Answer Recall that loading of the acyl carrier protein requires an initial addition of acetyl-CoA,followed by the addition of malonyl-CoA. Malonyl-CoA is normally produced by the addition ofCO2to acetyl-CoA by acetyl-CoA carboxylase.(a) In the presence of an excess of [14C]acetyl-CoA, the metabolic pool of malonyl-CoA be-comes labeled at C-1 and

Chapter 21 Lipid Biosynthesis Multiple Choice Questions 1. Which of the following is not required in the synthesis of fatty acids? A) Acetyl-CoA B) Biotin C) HCO3 (CO2) D) Malonyl-CoA E) NADH Biosynthesis of fatty acids and eicosanoids Pages: 833839 Difficulty: 2 Ans: E

Chapter 22 Biosynthesis of Amino Acids, Nucleotides, and Related Molecules Multiple Choice Questions 1. Which of the following statements about the fixation of atmospheric nitrogen (N2) into NH3 by living cells is false? A) It involves the transfer of eight electrons per mol

Answer Bacteria in the root nodules maintain a symbiotic relationship with the plant: theplant supplies ATP and reducing power, and the bacteria supply ammonium ion by reducingatmospheric nitrogen. This reduction requires large quantities of ATP. Answer Bacteria in the root nodules maintain a symbiotic relationship with the plant: theplant supplies ATP

Answer Oxytocin and vasopressin are recognized by different receptors, typically found indifferent cell types. These receptors are coupled to different downstream effects in theirtarget cells. Answer Oxytocin and vasopressin are recognized by different receptors, typically found indifferent cell types. These receptors are coupled to different downstream effects in theirtarget cells.

Chapter 23 Integration and Hormonal Regulation of Mammalian Metabolism Multiple Choice Questions 1. The radioimmunossay (RIA) is based on competition of unlabeled and radiolabeled: A) antibodies for binding to a hormone. B) antibodies for binding to a receptor. C) hormone for binding

Chapter 24 Genes and Chromosomes Multiple Choice Questions 1. The most precise modern definition of a gene is a segment of genetic material that: A) codes for one polypeptide. B) codes for one polypeptide or RNA product. C) determines one phenotype. D) determines one

Answer The T2 DNA molecule has (120 106)/650 1.8 105nucleotide pairs. Recall fromChapter 8 that a base pair occupies a length of 3.4 , so the length of the T2 DNA molecule is(1.8 105bp)(3.4 /bp) 6.1 105 6.1 104nmThus, the DNA molecule is 6.1 104nm/210 nm 290 times the length

Chapter 25 DNA Metabolism Multiple Choice Questions 1. The Meselson-Stahl experiment established that: A) DNA polymerase has a crucial role in DNA synthesis. B) DNA synthesis in E. coli proceeds by a conservative mechanism. C) DNA synthesis in E. coli proceeds by a

Answer This experiment is an extension of the Meselson-Stahl experiment, which demon-strates that replication in E. coli is semiconservative. After three generations the molar ratioof 15N14N DNA to 14N14N DNA is 2/6 0.33. Answer This experiment is an extension of the Meselson-Stahl experiment, which demon-strates that replication in E. coli is

Answer(a) Elongation of the RNA transcript in E. coli proceeds at about 50 to 90 nucleotides persecond. Thus, the time required to produce the primary transcript in this case is60 to 100 s(b) Because elongation occurs at 50 to 90 nucleotides per second, in 10 seconds the bubbletravels(10 s)(50 to

Chapter 26 RNA Metabolism Multiple Choice Questions 1. RNA polymerase: A) binds tightly to a region of DNA thousands of base pairs away from the DNA to be transcribed. B) can synthesize RNA chains without a primer. C) has a subunit called

Chapter 27 Protein Metabolism Multiple Choice Questions 1. A certain bacterial mRNA is known to represent only one gene and to contain about 800 nucleotides. If you assume that the average amino acid residue contributes 110 to the peptide molecular weight, the largest polypeptide

S-301 S-301 S-301 Answer The genetic code is nonoverlapping, unpunctuated, and in triplet (see Fig. 277).(a) GlyGlnSerLeuLeuIle(b) LeuAspAlaPro (UAA is a stop codon)(c) HisAspAlaCysCysTyr(d) MetAspGlu in eukaryotes; fMetAspGlu in prokaryotes Answer The genetic code is nonoverlapping, unpunctuated, and in triplet (see Fig. 277).(a) GlyGlnSerLeuLeuIle(b) LeuAspAlaPro (UAA is a stop codon)(c) HisAspAlaCysCysTyr(d) MetAspGlu in eukaryotes;

S-311 S-311 S-311 Answer The mRNA from the trpEDCBA operon encodes several enzymes for tryptophanbiosynthesis; the trpB and trpA genes encode tryptophan synthase. The complete trp mRNAis synthesized only when the concentration of tryptophan (actually, that of charged Trp-tRNA)is low. This is the result of repression and attenuation (see Problem 7). There is

Chapter 28 Regulation of Gene Expression Multiple Choice Questions 1. Housekeeping genes in bacteria are commonly expressed constitutively, but not all of these genes are expressed at the same level (the same number of molecules per cell). The primary mechanism responsible for variations in the

Chapter 3 Amino Acids, Peptides, and Proteins Multiple Choice Questions 1. Amino acids Page: 72 Difficulty: 1 Ans: C Page: 72 Difficulty: 1 Ans: C Page: 72 Difficulty: 1 Ans: C The chirality of an amino acid results from the fact that its carbon:

Answer Rotating the structural representation 180in the plane of the page puts the mosthighly oxidized groupthe carboxyl (OCOO) groupat the top, in the same position as theOCHO group of glyceraldehyde in Figure 34. In this orientation, the a-amino group is on theleft, and thus the absolute configuration of the citrulline

(a) The higher the bond order (double or triple vs. single), the shorter and stronger are thebonds. Thus, bond length is an indication of bond order. For example, the CPN bond isshorter (1.27 ) and has a higher order (n 2.0) than a typical CON bond (length 1.49 , n

Chapter 4 The Three-Dimensional Structure of Proteins Multiple Choice Questions 1. Overview of protein structure Pages: 114115 Difficulty: 1 Ans: D Pages: 114115 Difficulty: 1 Ans: D Pages: 114115 Difficulty: 1 Ans: D All of the following are considered weak interactions in proteins

Answer Protein B has a higher affinity for ligand X. The lower Kdindicates that protein B willbe half-saturated with bound ligand X at a much lower concentration of X than will protein A.Because Ka1/Kd, protein A has Ka106M1; protein B has Ka109M1. Answer Protein B has a higher affinity for ligand

Chapter 5 Protein Function Multiple Choice Questions 1. Reversible binding of a protein to a ligand: oxygen-binding proteins Page: 153 Difficulty: 2 Ans: D Page: 153 Difficulty: 2 Ans: D Page: 153 Difficulty: 2 Ans: D The interactions of ligands with proteins: A)

Chapter 6 Enzymes Multiple Choice Questions 1. An introduction to enzymes Pages: 183184 Difficulty: 1 Ans: A Pages: 183184 Difficulty: 1 Ans: A Pages: 183184 Difficulty: 1 Ans: A One of the enzymes involved in glycolysis, aldolase, requires Zn2+ for catalysis. Under conditions of zinc

Answer After an ear of corn has been removed from the plant, the enzyme-catalyzed conver-sion of sugar to starch continues. Inactivation of these enzymes slows down the conversion toan imperceptible rate. One of the simplest techniques for inactivating enzymes is heat denatura-tion. Freezing the corn lowers any remaining enzyme activity

Chapter 7 Carbohydrates and Glycobiology Multiple Choice Questions 1. Monosaccharides and disaccharides Page: 243 Difficulty: 1 Ans: C Page: 243 Difficulty: 1 Ans: C Page: 243 Difficulty: 1 Ans: C To possess optical activity, a compound must be: A) a carbohydrate. B) a

Answer With reduction of the carbonyl oxygen to a hydroxyl group, the stereochemistry atC-1 and C-3 is the same; the glycerol molecule is not chiral. Answer With reduction of the carbonyl oxygen to a hydroxyl group, the stereochemistry atC-1 and C-3 is the same; the glycerol molecule is not chiral. Answer With

Answer All purine ring nitrogens (N-1, N-3, N-7, and N-9) have the potential to form hydrogenbonds (see Figs 81, 811, and 23). However, N-1 is involved in Watson-Crick hydrogenbonding with a pyrimidine, and N-9 is involved in the N-glycosyl linkage with deoxyribose andhas very limited hydrogen-bonding capacity. Thus, N-3 and

Chapter 8 Nucleotides and Nucleic Acids Multiple Choice Questions 1. Some basics Page: 282 Difficulty: 1 Ans: E Page: 282 Difficulty: 1 Ans: E Page: 282 Difficulty: 1 Ans: E The compound that consists of ribose linked by an N-glycosidic bond to N-9 of

Chapter 9 DNA-Based Information Technologies Multiple Choice Questions 1. Studying genes and their products Pages: 314316 Difficulty: 1 Ans: C Pages: 314316 Difficulty: 1 Ans: C Pages: 314316 Difficulty: 1 Ans: C Restriction enzymes: A) act at the membrane to restrict the passage of certain

Answer Type II restriction enzymes cleave double-stranded DNA within recognitionsequences to create either blunt-ended or sticky-ended fragments. Blunt-ended DNA frag-ments can be joined by the action of T4 DNA ligase. Sticky-ended DNA fragments can bejoined by either E. coli or T4 DNA ligases, provided that the sticky ends are complementary.Sticky-ended