Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book.
Exploring the Mechanism of Lipid Transport by a Flippase ATP-dependent flippases art closely related in their structures to ion pumps like the plasma membrane Na+, K+-ATPase and sarcoplasmic reticulum Ca2+-ATPase, but they contend with a novel dilemma not shared by the ion transport systems. Consult the following reference and. summarize the structural features common to the flippases and P-type ATPases, and describe how the flippase solves the "giant substrate problem". (Vestegaard, A.L., Coleman, J.A., Lemmin. T., et al., 2014. Critical roles of roles ucine-364 and adjacent residues in a hydrophobic gate control of phospholipid transport by the mammalian P4-ATPase ATPSA2. Proceedings of the National Academy of Sciences, USA 111:16629-16633.)
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Biochemistry
- Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Understanding the Densities of Membrane Components Sucrose gradients for separation of membrane proteins must be able to separate proteins and protein—lipid complexes with a wide range of densities, typically 1.00 to 1.35 g/mL. a. Consult reference books (such as the CRC Handbook of Biochemistry ) and plot the density of sucrose solutions versus percent sucrose by weight (g sucrose per 100 g solution), and versus percent by volume (g sucrose per 100 mL solution). Why is one pint linear and the other plot curved? b. What would be a suitable range of sucrose concentrations for Separation of three membrane-derived protein—lipid examples with densities of 1.03, 1.07, and 1.08 g/mL?arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Understanding the Phase Transitions of Membrane Phospholipids Discuss the effects on the lipid phase transition of pure dimyristoyl phosphatidylcholine vesicles of added (a) divalent cations, (b) cholesterol, (c) distearoyl phosphatidylscrine. (d) dioleoyl phosphatidylcholine, and (e) integral meinbrane proteins.arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. The Dimensions of Mitochondria and Their Constituents Assume that mitochondria are cylinders 1.5 m in length and 0.6 m in diameter. (Section 1.5) What is the volume of a single mitochondrion? Oxaloacetate is an intermediate in the citric acid cycle, an important metabolic pathway localized in the mitochondria of eukaryotic cells. The concentration of oxaloacetate in mitochondria is about 0.03 . How many molecules of oxaloacetate are in a single mitochondrion?arrow_forward
- Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Determining 'the Concentration Limits of an Active Transport System (Integrates with Chapter 3.) Fructose is present outside a Cell at 1 M concentration. An active transport system in the plasma membrane transports fructose into this cell, using the free energy of ATP hydrolysis to drive fructose uptake. What is the highest intracellular concentration of fructose that this transported system can generate? Assume that one fructose is transported per ATP hydrolyzed; that ATP is hydrolyzed on the intracellular surface of the membrane; and that the concentrations of ATP, ADP, and Pi are 3mM, 1mM, and 0.5mM, respectively. T = 298 K. [Hint: Refer to Chapter 3 to recall the effects of concentration on free energy of ATP hydrolysis.)arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Determining the Electrochemical Potential of a Sodium Ion Gradient Consider a phospholipid vesicle containing 10mM Na+ ions. The vesicle is bathed in a solution that contains 52mM Na+ ions, and the electrical potential difference across the vesicle membrane = outside- outside = -30mV. What is the electrochemical potential at 25C for Na+ ions?arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Understanding Diffusion of Proteins in Membranes Protein lateral motion is much slower than that of lipids because proteins are larger than lipids. Also, some membrane proteins can diffuse freely through the membrane, whereas others art bound or anchored to other protein structures, in the membrane. The diffusion constant for the membrane protein fibronectin is approximately 0.7 X 10-12 cm/sec, whereas that for rhodopsin is about 3 X10-9 cm/sec. Calculate the distance traversed by each of these proteins in 10 msec. What could you surmise about the interactions of these proteins with other membrane components?arrow_forward
- Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Graphical Analysis of MWC Allosteric Enzyme Kinetics (Integrates with Chapter 1.1) Draw both Line weaver-Burk plots and Hanes-Woolf plots for an MWC allosteric enzyme system, showing separate curves for the kinetic response in (a) the absence of any effectors, (b) the presence of allosteric activator Λ, and (c) the presence of allosteric inhibitor I.arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Phosphorylation of Proteins Introduces New Properties Phosphoproteins are formed when a phosphate group is esterified to an —OH group df a Ser, Thr, or Tyr side chain. At typical cellular pH values, this phosphate group bears two negative charges (— OPO32:_). Compare this side-chain modification to the 2U side chains of the Common amino acids found in proteins and comment on the novel properties that it introduces into side-chain possibilities.arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Quantitative Relationships Between Rate Constants to Calculate Km, Kinetic Efficiency (kcat/Km) and Vmax - I Measurement of the rate constants for a simple enzymatic reaction obeying Michaelis-Menten kinetics gave the following results: k1=2108M1sec1k1=1103sec1k2=5103sec1a. What is Ks, the dissociation constant for the enzyme-substrate complex? b. What is Km, the Michaelis constant for this enzyme? c. What is kcat (the turnover number) for this enzyme? d. What is the catalytic efficiency (kcat/Km) for this enzyme? e. Does this enzyme approach kinetic perfection? (That is, does kcat/Km approach the diffusion-controlled rate of enzyme association with substrate?) f. If a kinetic measurement was made using 2 nanomoles of enzyme per mL and saturating amounts of substrate, what would Vmax equal? g. Again, using 2 nanomoles of enzyme per mL of reaction mixture, what concentration of substrate would give v = 0.75 Vmax? h. If a kinetic measurement was made using 4 nanomoles of enzyme per mL and saturating amounts of substrate, what would Vmax equal? What would Km equal under these conditions?arrow_forward
- Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. The Dimensions of Eukaryotic Cells and Their ConstituentsAssume that liver cells are cuboidal in shape, 20 m oil a side. (Section 1.5) How many liver cells laid end to end would fit across the diameter of a pinhead? (Assume a pinhead diameter of 0.5 mm) What is the volume of a liver cell? (Assume it is a cube.) What is the surface area of a liver cell? What is the surface-to- volume ratio of a liver cell? How does this compare to the surface-to-volume ratio of an E. coli cell (compare this answer with that of problem 3c)? What problems must cells with low surface-to-volume ratios confront that do not occur in cells with high surface-to-volume ratios? A human liver cell contains two sets of 23 chromosomes, each set being roughly equivalent in information content. The total mass of DNA contained in these 46 enormous DNA molecules is 4 1012 Because each nucleotide pair contributes 660 daltons to the mass of DNA and 0.34 run to the length of DNA, what is the total number of nucleotide pairs and the complete length of the DNA in a liver cell? How does this length compare with the overall dimensions of a liver cell? The maximal information in each set of liver cell chromosomes should be related to the number of nucleotide pairs in the chromosome set's DNA. This number can be obtained by dividing the total number of nucleotide pairs just calculated by 2. What is this value? If this information is expressed in proteins that average 400 amino acids in length and three nucleotide pairs encode one amino acid in a protein, how many different kinds of proteins might a liver cell be able to produce? (In reality, liver cell DNA encodes approximately 20,000 different proteins. Thus a large discrepancy exists between the theoretical information content of DNA in liver cells and the amount of information actually expressed.)arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Determining the Length of a Keratin Molecule The central rod domain of a keratin protein is approximately 312 residues in length. What is the length (in A) of the keratin rod domain? If this same peptide segment were a true -helix how long would it be? If the same segment were a -sheet, what would its length be?arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Assessing the Formation and Composition of Limit Dextrins Prolonged exposure of amylopectin to starch phosphorylase yields a substance called a limit dextrin. Describe the chemical composition of limit dextrins. and draw a mechanism for the enzyme-catalyzed rcactioa that can begin the breakdown of a limit dextrin.arrow_forward
- BiochemistryBiochemistryISBN:9781305577206Author:Reginald H. Garrett, Charles M. GrishamPublisher:Cengage Learning