1 Draw draw the Haworth projection for 3-amino-3-deoxy-a-D-talofuranose-6-sulfate. Draw the pyranose
form of I-D-altrouronic acid in its most stable CHAIR conformation
2a. Insulin receptors are part of a signal transduction pathway involving a multifunctional transmembrane
protein, receptor tyrosine-kinase (1) IN YOUR OWN WORDS, explain what "signal transduction is and
describe the "communication advantages of a signal transduction system. (2) For the insulin signaling
system, supply the specific name of the: first messenger; membrane receptor, transducer; effector enzyme;
second messenger; and cytoplasmic effector target(s).
2b Certain mutations of the ß-subunit of the insulin receptor result in the loss of enzymatic activity of the
subunit leading to diabetes Describe the specific role of the ß-subunit and explain why loss of activity of
these subunits would result in diabetes.
3a. Determine which of the following pairs are epimeric. Although you'll need to analyze the structures, do
NOT include them with your response. Simply indicate for any epimeric pairs the carbon that is
epimerized. For nonepimeric pairs, list the specific stereochemical structural relationship, as appropriate.
(a) D-ribulose and D-arabinose
(b) L-idose and D-glucose
(c) D-xylose and L-xylose;
(d) D-sorbose and D-tagatose
(e) D-galactose and D-talose.
3b Deduce and draw the structure of a disaccharide given the following information: Hydrolysis of the
disaccharide produces ONLY D-glucose; it is hydrolyzed by a-glucosidase but not B-glucosidase; and it
does NOT reduce copper (II)
4a. Outline the significant structural features of glycogen. Be sure to use proper chemistry terminology.
4b. IN YOUR OWN WORDS, explain with few sentences why havinga highly branched storage
polysaccharide would be beneficial to animals' metabolism
5a. Draw a proper line-bond structure for a sphingomyelin that bears a stearic acid residue. What functional
group is formed in joining the fatty acid to the structure?
5b. Would you expect these lipids (5a) to assemble into micelles or bilayers in aqueous solution? Explain
your choice using appropriate biochemical and chemical terminology. A schematic to helpillustrate your
response would also be helpful.
6. The oligosaccharide component of glycoproteins can be difficult to characterize owing to
microbeterogeneity. What is microheterogeneity with respect to glycoproteins? Explain in adequate
7. Animal cells are enclosed by their cell membrane. Describe (in few sentences) the forces that stabilize
cell membranes Considering the shear forces that would be inflicted by movement, why don't cell
membranes break apart as the animal moves? What model best applies to these supramolecular
8. Animals such as cows do not produce cellulase; however, these herbivores depend heavily on cellulose
as a food source. Explain using proper terminology.
9a. Examine the structure of the cardiotonic glycosides oubain shown. Briefly explain why this substance is
referred to as a 'glycoside' Based upon its structure, to what specific biomolecular class does this oubain
9b Oubain and related compounds increase cardiac contractility by inducing increased calcium ion
concentration in these heart muscle cells by inhibiting NaKATPase Research and describe (ina short
paragraph) how inhibition of the NaKATPase ultimately results in changes in cellular calciumion
concentrations Be sure to provide adequate details about the other 'protein' that is involved.
10a. When the base cytosine is deaminated, uracil is produced. Draw both of these pyrimidine bases.
Consider this information and then speculate as to why the base thymine is "included in DNA molecules
instead of having uracil as one of the four bases used.
10b Uracil is one of the four bases in RNA. Why would the possible deamination of cytosine be less
problematic ifit were to occurin an RNA molecule versus ina DNA molecule? Briefly explain.
11. The aquaporins provide for rapid transport (3 108 water molecules see channel) of water across
cellular membranes especially in kidney and red blood cells. Explain how this process of water transport
differs from simple diffusion of water across a membrane Why would this transport process expected to be
much more rapid than simple diffusion? Be sure to use proper chemistry terminology.
12a. Bacterial cell cultures are typically maintained at 37o (1) Describe the effects that would
initially/mmediately happen to the bacterial membranes when their incubation temperature is raised to 45o
C; and then, (2) describe how the fatty acid composition of their membrane lipids would likely change in
response to being incubated at 45o C.
12b. Research (you do NOT have to draw a structure) the hopanoids how could these substances
contribute to the stabilization of bacterial cellular membranes when temperature varies? Briefly explain
using proper chemistry terminology.
13a. Demonstrate mechanistically the relative instability of RNA as comparedto DNA. Comment (few
sentences) on why this difference in stability is biologically advantageous both with respect to stability of
DNA and instability of RNA (mRNA, specifically).
13b. Under physiological conditions, typical double-stranded DNA is in the form, B-DNA; however, DNA-
RNA hybrids adopt the structural features like that of A-DNA. Considering the structural differences
between DNA and RNA polynueleotides and the structural features of A-DNA, explain this phenomenon
14. Nutraceuticals are products that are believed to have some beneficial effect but are not strictly defined
as either food or drug. Why might an individual suffering from osteoarthritis be tempted to consume the
nutraceutical glucosamine? What is the rationale for its use in the treatment of osteoarthritis?
15 IN YOUR OWN WORDS, outline (no more thant or three sentences for each) three distinetly
different general 'control' methods that are utilized in controlling flux through biochemical pathways.
16. In some autoimmune diseases, an individual develops antibodies that can recognize both of the cellular
constituents, nucleie acids and phospholipids. Explain, using proper chemistry terminology the structural
basis for the cross-reactivity of these antibodies.
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2b. Certain mutations of the β-subunit of the insulin receptor result in the loss of enzymatic activity of the subunit leading to diabetes. Describe the specific role of the β-subunit and explain why loss of activity of these subunits would result in diabetes.
The tyrosine kinase domain of each β chain catalyzes autophosphorylation of tyrosine residues in the adjacent kinase domain. Due to the mutation, the subunits lack tyrosine-kinase activity and cannot catalyze autophosphorylation or other phosphorylation reactions. Autophosphorylation of the beta subunits of the receptor activates a local tyrosine kinase, which in turn causes phosphorylation of multiple other intracellular enzymes including a group called insulin-receptor substrates (IRS). Different types of IRS (e.g., IRS-1, IRS-2, IRS-3) are expressed in different tissues. The net effect is to activate some of these enzymes while inactivating others.
The hormone insulin stimulates high rates of glucose uptake into skeletal and heart muscle cells and adipocytes via the transporter GLUT4.When insulin binds to receptors on the cell surface, intracellular vesicles that have GLUT4 embedded in their membranes fuse with the cell surface by exocytosis thereby increasing the capacity of the cells to transport glucose. When there is loss of β-subunit activity, insulin can`t stimulate glucose transport into the cell so glucose concentration increase outside the cell....