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 Constituents Assume that liver cells are cuboidal in shape, 20 μm 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 × 10 12 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.)

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. Cell Structure Without consulting the figures in this chapter, sketch the characteristic prokaryotic and eukaryotic cell types and label their pertinent organelle and membrane systems. (Section 1.5)

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 Prokaryotic Cells and Their Constituents Escherichia coli cells are about 2 Î¼m (microns) long and 0.8 Î¼m in diameter. (Section 1.5) a. How many E. coli cells laid end to end would fit across the diameter of a pinhead? (Assume a pinhead diameter of 0.5 mm.) b. What is the volume of an E. coli cell? (Assume it is a cylinder, with the volume of a cylinder given by V=r2h , where = 3.14.) c. What is the surface area of ail E coli cell? What is the surface-to- volume ratio of an E coli cell? d. Glucose, a major energy-yielding nutrient, is present in bacterial cells at a concentration of about 1 mM. What is the concentraÂ¬tion of glucose, expressed as mg/mL? How many glucose molecules are contained in a typical E. coli cell? (Recall that Avogadroâ€™s number =6.0231023 .} e. A number of regulatory proteins are present in E. coli at only one or two molecules per cell. If we assume that an E. coli cell contains just one molecule of a particular protein, what is the molar concentration of this protein in the cell? If the molecular weight of this protein is 4023 , what is its concentration, expressed as mg/mL? f. An E coli cell contains about 15,000 ribosomes, which carry out protein synthesis. Assuming ribosomes are spherical and have a diameter of 20 nm (nanometers), what fraction of the E. coli cell volume is occupied by ribosomes? g. The E coli chromosome is a single DNA molecule whose mass is about 3109 daltons. This macromolecule is actually a linear array of nucleotide pairs. The average molecular weight of a nucleotide pair is 660, and each pair imparts 0.34 nm to the length of the DNA molecule. What is the total length of the E. coli chromosome? How does this length compare with the overall dimensions of an E. coli cell? How many nucleotide pairs does this DNA contain? The average E. coli protein is a linear chain of 360 amino acids. If three nucleoÂ¬tide pairs in a gene encode one amino acid in a protein, how many different proteins can the E. coli chromosome encode? (The answer to this question is a reasonable approximation of the maximum number of different kinds of proteins that can be expected in bacteria.)

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. Cells as Steady-State Systems Describe what is meant by the phrase "cells tire steady-state systems." (Section 1.4)

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. Interpreting Kinetics Experiments from Graphical Patterns The following graphical patterns obtained from kinetic experiments have several possible interpretations depending on the nature of the experiment and the variables being plotted. Give at least two possibilities for each.

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. Intracellular Transport of Proteins The endoplasmic reticulum (HR) is a site of protein synthesis. Proteins made by ribosomes associated with the ER may pass into the EH membrane or enter the lumen of the HR. Devise a pathway by which: a plasma membrane protein may reach the plasma membrane. a secreted protein may be deposited outside the cell. (Section 1.5)

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 Biosynthetic Capacity of Cells The nutritional requirements of Escherichia coli cells are far simpler than those of humans, yet the macromolecules found in bacteria are about as complex as those of animals. Because bacteria can make all their essential biomolecules while subsisting on a simpler diet, do you think bacteria may have more biosynthetic capacity and hence more metabolic complexity than animals? Organize your thoughts on this question, pro and con, into a rational argument. (Section 1.5)

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 proteinâ€”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 proteinâ€”lipid examples with densities of 1.03, 1.07, and 1.08 g/mL?

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. Solving the Sequence of an Oligopeptide From Sequence Analysis Data Amino acid analysis of ail oligopeptide seven residues long gave The following fads were observed: a. Trypsin treatment had no apparent effect. b. The phenylthiohydantoin released by Lid mini degradation was c. Brief chymotrypsin treatment yielded several products, including a dipeptide and a tetrapeptide. The amino acid composition of the tetrapeptide was Leu, Lyi. and Met. d. Cyanogen bromide treatment yielded a dipeptide, a tetrapeptide, and free Lys. What is the amino acid sequence of this heptapeptide?

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. Solving the Sequence of an Oligopeptide From Sequence Analysis Data Amino acid analysis of a decapeptide revealed the presence of the following products: The following facts were observed: Neither car boxy peptidase A nor B treatment of the- decapeptide had any effect. Trypsin treatment yielded two tetrapcptides and free Lys. Clostripain treatment yielded a tetrapcptide and a hexapeptidc. Cyanogen bromide treatment yielded an octapeptide and a dipeptide of sequence NP (using the one-letter codes). Chymotrypsin treatment yielded two tripeptides and a telrapeptide. The N-terminal chymotryptic peptide had a net charge of â€” 1 at neutral pi I and a net charge of â€”3 al pH 12. One cycle of Ed man degradation gave the PTH derivative What is the ammo acid sequence of this decapeptide?

Answers to all problems are at the end Î¿Î“this book. Detailed solutions are available in the Student Solutions Manual. Study Guide, and Problems Book. Superbug infections are becoming more common around the world. Many of these infections arise from the action of -lactamases, of which there are several types with different mechanisms of action. Consult the end-of-chapter reference by von Nussbaum and Schiffer and write detailed mechanisms for the serine -lactamases and metallo- -lactamases.

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 Strength of Weak Forces Determines the Environmental Sensitivity of Living Cells Why does the central role of weak forces in biomolecular interactions restrict living systems to a narrow range of environÂ¬mental conditions? (Section 1.4)

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. To fully appreciate the elements of secondary structure in proteins, it is useful to have a practical sense of their structures. On a piece of paper, draw a simple but large zigzag pattern to represent a -strand. Then fill in the structure, drawing the locations of the moms of the chain on this zigzag pattern. Then draw a simple, large coil on a piece of paper to represent an -helix. Then fill in the structure, drawing the backbone atoms in the correction locations along the coil and indicating the locations of the R groups in your drawing.

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