Reference no: EM132279052

Question 1. Maltose, trehalose, and cellobiose are all disaccharides of glucose that differ in the nature of the glycosidic bond attaching the two glucosyl residues. In maltose, the linkage is α(1→4); in trehalose, the linkage is α(1→1); in cellobiose the linkage is β(1→4). Based upon this information, answer the following questions:

1a. Which of these disaccharides is a non-reducing sugar? Explain your reasoning.

1b. Which of these disaccharides results from the breakdown of cellulose? Explain your reasoning.

1c. Which of these disaccharides results from the breakdown of amylose? Explain your reasoning.

Question 2. Draw the Haworth projection of the hypothetical disaccharide made of two fructose molecules, with the first (left) being the β anomer, the second (right) being the α anomer, both in furanose form, and linked by a 2→6 glycosidic bond. Number the carbons and circle the anomeric carbons in both monosaccharide units.

*Question 3. Draw the glycerophospholipid having the fatty acid with the designation 18:0 at C1, the fatty acid with the designation 20:4n-6 at C2, and the head group serine attached to the phosphate at C3. What is the common name of the fatty acid (Table 9-1) liberated by the enzyme phopspholipase A2 and what general class of signal molecules is formed from the metabolism of this fatty acid?

Question 4a. It is possible to label membrane proteins with specific reagents. If this reagent is impermeable to cell membranes and you used it to label membrane proteins from intact red blood cells, would you expect the N-terminus or C-terminus (or both) of glycophorin A to be labeled? Explain.

Question 4b. If you used the same reagent in a preparation of lysed red blood cells, would you expect the N- terminus or C-terminus (or both) of glycophorin A to be labeled? Explain.

Question 5. Both cytochrome c and cytochrome c oxidase are proteins involved in mitochondrial electron transport (Chapter 19). You can separate cytochrome c from the mitochondrial membrane with a modest increase in salt concentration (e.g., 200 mM NaCl), but cytochrome c oxidase remains associated with the membrane even at high concentrations of salt (e.g., 1 M NaCl). Explain why this is so and propose a treatment that might release cytochrome c oxidase from the mitochondrial membrane.

Question 6a. Calculate the free energy of transport of Na+ across the plasma membrane, moving from the extracellular medium into the cell, under the following conditions: [Na+]out = 145 mM; [Na+]in = 12.0 mM; T = 37.0°C; ΔΨ = - 60.0 mV (inside negative).

Question 6b. If sodium-coupled glucose transport was able to use the energy from part 6a with 100% efficiency, and the stoichiometry of sodium-coupled glucose transport was 1 Na+ : 1 glucose, then was is the maximum concentration gradient against which this process could account for glucose uptake by cells (at 37.0°C)?

Note: Solve question 3 only