Biochem 3 Exam Multiple Choice
Terms in this set (22)
DNA microarrays can be used for which of the following?
a-d are all possible uses for DNA microarray
a. comparing gene expression between two developmental stages of an organism
b. comparing gene expression between normal cells and cancer cells
c. determining if two genes are expressed at the same time
d. viewing many different genes all in the same experiment
healthy bone development
Which drug inhibits the cyclooxygenase enzyme that converts arachidonic acid to prostaglandins and thromboxanes?
Phospholipases cut where on the glycerophospholipid shown? (photo)
I and III
The function of the aquaporin is to
transport water molecules
What is true about the insulin receptor?
the receptor is phosphorylated on its cytoplasmic domain
4 different kinases involved
What is true about ΔG'o and Keq'?
to get overall values, individual ΔG'o are added and Keq' are multiplied
if keq is large, delta G is negative
The NET energy yield resulting from one molecule of glucose going through glycolysis is?
2 ATP, 2 NADH
enzyme in glycolysis
enzyme in glycolysis
beaks a 6-carbon reactant into 3 carbon products
Will the reaction shown run as written under standard conditions? (is it spontaneous?)
Ubiquinone + NADH + H+ <----> Ubiquinol + NAD+
Yes, ΔE'o = (0.045 + 0.320) = 0.365 volts; ΔG'o = - (2)(96500 J/mol K) (0.365 V) = negative number so the reaction will run as written or be spontaneous as written
Phe could be found in the transmembrane domain
A GLUT is a glucose transporter that transports glucose through cell membrane down its concentration gradient so does not use energy
The ligand for the β-adrenergic receptor is _______EPINEPHRINE_________. Once the ligand binds, the G protein swaps GDP for ___GTP____. The activated G protein then interacts with __ADENYLYL CYCLASE______to make __cAMP____. The second messenger then activates __PROTEIN KINASE A______ which ___PHOSPHORYLATES_________ cellular proteins.
Explain one way in which the β-adrenergic receptor's signal is turned off (NOT desensitized).
1) the signal is no longer made,
2) cyclic nucleotide phosphodiesterase degrades cAMP,
3) the intrinsic GTPase activity of the G protein degrades GTP, and
4) phosphatases dephosphorylate and phosphorylated proteins
. Dr. Ima Starr wants to make a recombinant human hemoglobin fusion protein for study. Describe how she can do this starting with the hemoglobin gene (gene-Hb) from frogs and a bacterial plasmid pGSTR which has a cloning site right next to a glutathione-s-transferase gene, and ending with purification of the fusion protein. The cloning plasmid has an ampicillin resistance gene that is NOT interrupted by the cloning site. The fusion Hb protein that results will be covalently attached to glutathione-s-transferase, which binds tightly to the glutathione ligand. Mention something about how you can screen some of the bacterial cells and how chromatography is used for purification.
Dr. Starr would cut the plasmid and frog DNA with restriction enzymes making sure the ends are compatible. Then the recombinant plasmid would be made using DNA ligase and transformed into bacteria. The bacterial colonies that grow on ampicillin agar would have the plasmid. These colonies would be grown up and should express the fusion protein. The cells would then be lysed, and the extract subjected to glutathione affinity resin. The fusion protein could then be eluted from the column using excess glutathione. More than one colony should be grown up as it would be uncertain to know if every colony containing the plasmid also contains the full-length frog gene.
a) Describe the basic steps of receptor-signaling via the phospholipase C receptor system. Identify the role of phospholipase C, identify the three second messengers, and what enzyme gets activated.
b) Activation of this receptor results in phosphorylation of proteins. Write out the structure for a phosphorylated tyrosine.
a) A signal binds to the receptor causing the G protein to swap GTP for GDP and the alpha subunit becomes activated, translocates, and activates phospholipase C. Phospholipase C cleaves a membrane phosphatidyl inositol to IP3 and diacylglycerol. IP3 opens a Ca2+ channel and Ca2+ and diacylglycerol activate protein kinase C. Protein kinase C phosphorylates cellular proteins causing a cellular response.
a) Calculate the transport of a chloride ion across a cell membrane. The ion is moving from the inside to the outside of the cell at 37 oC. The transmembrane potential, inside (-) to outside is 45 mV. The concentration of chloride on the inside of the cell is 25 mM and the outside concentration is 135 mM.
b) Will the transport of the chloride in this case require active transport or facilitated diffusion?
a) ΔGt = RTlnC2/C1 + ZFΔΨ = (8.315 J/mol K)(310K)ln / + (-1)(96,500 J/mol V)(0.045 V)
= (4347) + (- 4342.5) = + 4.5 J/mol
b) ΔGt is (+) so it would require active transport or energy
Describe the process by which the β-adrenergic receptor is desensitized using β-ARK and β-arrestin. What is the difference (in general) between desensitization of this receptor and termination of its signal?
The receptor is phosphorylated by β-ARK on its cytoplasmic domain on Ser residues. The phosphorylation causes a binding site for β-arrestin, which blocks the action of the G protein. β-arrestin recruits other proteins needed for endocytosis and then the β-arrestin/receptor complex is internalized into the cell and removed from the cell surface. The receptor at this point can't interact with any signaling molecule so the response is dampened. This is different from termination because the signaling molecule, epinephrine, is still being produced. The effect is epinephrine is lessened in this case, not terminated. In termination the signaling molecule stops being produced (and there other ways to stop the signal, see question 14).
A cerebroside has one sugar group attached to a sphingolipid, a ganglioside has many (four or more).
Fabry, Gaucher, and Niemann-Pick diseases are all lipid or lysosomal storage diseases in which an enzyme responsible for degrading complex lipids is defective or missing. Not all of these diseases are fatal, but if not treated properly (with diet) can lead to permanent effects.
Cholera toxin ADP-ribosylates a G protein and therefore inactivates its intrinsic GTPase activity. The G protein remains turned on, cAMP levels are elevated, and the body response is to release water and ions. The resulting dehydration is severe enough that, if not treated by hydration therapy, can lead to death.
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