Lab Analysis

intermediate metabolism

homework
1) The concentrations of ATP, ADP, and AMP in a particular rat hepatocyte cell are 3.38 mM, 1.32 mM, and 0.29 mM, respectively. Using the information you used in problem 9, calculate the Gibbs Free Energy (?G) for the reaction
ATP AMP ? 2 ADP
under these conditions at 37°C. Give your answer in kJ/mol to one decimal (tenths) without units.
2) Given the the standard reduction potentials for cystine disulfide and NAD on Table 1 below, calculate the standard state reduction potential for the chemical reaction that follows. Give your answer in Volts to three decimals (thousandths) and do not include units.
Table 1. Standard Reduction Potentials of Some Biochemically Important Half-Reactions
Half-Reaction
??°’ (V)
NAD H 2e- ? NADH
-0.315
Cystine disulfide 2H 2e- ? 2 Cysteine
-0.340
Cystine disulfide NADH H ? 2 Cysteine NAD
3) A healthy cell produces ATP continuously. However, ATP is only one of four ribonucleoside triphosphates (together with CTP, GTP, and UTP) required in roughly equal amounts for synthesis of all the RNA in a cell (and there is a lot of RNA in a cell!). Which enzyme is responsible for maintaining the roughly equal cellular concentrations of the four ribonucleoside triphosphates?
a) Inorganic pyrophosphatase
b)Ribonuclease
c) Nucleoside diphosphate kinase
d) Chymotrypsin

4)Draw a schematic diagram for the steps leading up to the removal of two electrons from glyceraldehyde-3-phosphate to NAD by the enzyme GAP dehydrogenase. How does this dehydrogenation differ from similar reactions catalyzed by lactate dehydrogenase or yeast alcohol dehydrogenase. What is the advantage of using the mechanism of GAP dehydrogenase? (HINT: think of the role played by Pi in the GAP dehydrogenase enzyme mechanism

5) Use the half reaction reduction potentials found on Table 14-4 to calculate the standard state Gibb’s Free Energy (?G°’) for the reaction: (picture attached of chart)
Pyruvate NADH H ? Lactate NAD
If the steady state cellular concentrations of Pyruvate and Lactate are held fixed at 0.051 mM and 0.51 mM, respectively, then what is the ratio of [NAD ]/[NADH] below which this reaction begins to be energetically favorable at 37°C? Note that for this reaction the H ions are immediately buffered by proteins, metabolites, other small molecules, and even water in the cell cytoplasm so, effectively, they are available as needed and “disappear” as soon as they are produced. Therefore, you need not include the [H ] in your free energy calculations
6) Neatly create a diagram that shows each of the ten steps in glycolysis. Include the structures and names of each of the stable intermediates, the names of each of the enzymes, and the co-factors (ATP, NAD ) required and generated in the pathway.

Chemistry Discussion

Chemistry Assignment Help Humans have engaged in psychoactive drug use, sometimes in formal (ceremonial) settings and sometimes recreationally, since before recorded history. It has only been in the last century or so that abuse and addiction have become large-scale problems. Using the literature and your own insights into these issues, formulate an argument as to why the problem has reached its current scale. In your discussion, evaluate the employment of psychoactive drugs from the aspects of a risk-benefits analysis and ethical considerations such as the risk of addiction versus the cost of punitive action. Also explain purely pharmacological issues such as pharmacokinetics and routes of drug administration and dose. If needed, include factors such as supply, cultural attitudes to drug use, and the context of drug use.

Lab Analysis

Like the speed of a car, a rate is always a positive number. permanganate concentration would be written:
? = rate
? 4[KMnO ]
? t
Therefore, the rate based on the potassium
Eqn. 1
Here ?[KMnO4] represents the change in potassium permanganate concentration during the time interval ?t. Since the concentration decreases, the minus sign is needed to make the rate come out positive.
The rate law expression gives the dependence of the reaction rate on the concentration of reactants. For the reaction under investigation, we write the rate law as
rate = k[KMnO4]X[H2C2O4]Y
Eqn. 2
where the [ ] indicates molarity (moles/L), and X and Y are called the orders with respect to potassium permanganate (X) and oxalic acid (Y), respectively. The values of X and Y are not always integers; they are often fractions or decimal numbers.
The overall rate order would be “X Y”.
Finally, the constant, k, is
called the rate constant for the reaction and it is a constant at any one temperature. Suppose we do two experiments, keeping the potassium permanganate concentration constant for both, [KMnO4l1, but varying the oxalic acid concentration, [H2C2O4]1 and [H2C2O4]2. We could write two rate expressions now:
By reversing the process (varying the concentration of KMnO4 and keeping the concentration of H2C2O4 constant), we can find the value of X.
Then we can solve for the overall rate order, X Y.
constant, k, can be determined by substituting X and Y into the rate expression in Eqn. 2.
The rate
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Precautions:
* You MUST wear safety goggles and a lab coat at all times while in the laboratory.
* It is always a good idea to:
wash your hands well if in contact with chemicals
change gloves when they start degrading or get torn
wash your lab bench well to remove any spills
* All solutions should be placed in the aqueous waste beaker in the waste hood unless they contain only water or you are specifically told in the manual procedures that it is okay to rinse them down the drain. DO NOT PUT ANYTHING INTO THE BIG WASTE JUG.
* Pipets should be used only with bulbs or pumps. NO PIPETING BY MOUTH.
* All normal safety rules must be obeyed, including any special precautions issued by your instructor.
* KMnO4 (potassium permanganate) stains skin and clothes, the purple color changes to dark brown. It will wear off the skin with normal washing, but will cause a permanent stain on clothing.
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Procedure:
Using 3 clean small, labelled beakers and a graduated cylinder, obtain the following:
? ~ 50 mL of distilled water
? ~ 20 mL of 0.130 M KMnO4
? ~ 70 mL of 0.755 M H2C2O4
?. A 6×6 plastic, red test tube rack
A. Record the temperature of the lab in °C into your lab notebook.
The solutions in step A will be used to prepare the concentration series for the experiments. A table of the solution combinations is given below. The subsequent procedure describes how the solutions are to be mixed.
Table : 1
ReactantsExperiment #1Experiment #2Experiment #3distilled water6.00 mL1.00 mL5.00 mL0.130M KMnO41.00 mL1.00 mL2.00 mL0.755 M H2C2O45.00 mL10.00 mL5.00 mLTotal Volume12.00 mL12.00 mL12.00 mL[KMnO4], M0.01080.01080.0217[H2C2O4], M0.3140.6290.315Determination #1: Calculate the molarity of KMnO4 and H2C2O4 for each set-up in Table 1.
Example: (Experiment #1 Column)
(0.130 M KMnO 4 )(1.00 mL KMnO 4 ) 12.00 mL solution
= 0.0108 M
**Use a similar approach for the oxalic acid concentration.
Using disposable pipets measure 6.00 mL of distilled water and 5.00 mL of oxalic acid into a clamped test tube equipped with a magnetic rice grain stir bar and stirring.
One partner should measure 1.00 mL of potassium permanganate and prepare to add it to the test tube. Thether partner should be ready to start the timer when the permanganate is added.

solution will change color from purple to red to yellow. disappears from the solution.
Stir immediately.
The
Record the time when the red completely
Dispose of the test tube contents in the designated beaker located in the hood. Obtain a new, clean and dry the test tube and repeat steps (C) and (D), rotating duties of the partners, for a total of 3 trials.
Repeat steps (C) and (D) for the amounts in both the Experiment #2 and the Experiment #3 columns and record the data into your lab notebook.
Lab Report Format
Purpose Section:
What was the overall point of doing this lab? Go through each part and briefly describe what you did, why you did it and how you did it. Be specific and don’t just copy the objective in the lab manual that will not accrue any points.
Procedure Section:
‘Followed the experimental procedure as per the laboratory manual’
Then follow that with any variations that were made to the procedure.
Data Section:
Don’t forget to include all units. In tables, the units belong in the heading in parentheses, not after every single number in the table for that row.
The data tables for this lab are listed below.
DON’T FORGET SIG FIGS!
These should be reproduced in both your notebook and in your written lab report.
Table : 2
T =oC__25___
Trial[KMnO4](M)[H2C2O4](M)time (s)Rate1 = [KMnO4]/time10.01080.314287.410.000037620.01080.314318.440.000033930.01080.314282.310.0000383
Average Rate ____________________
Standard dev. ____________________
95% conf., ? ____________________
Table : 3
T =oC __25___
Trial[KMnO4] (M)[H2C2O4](M)time (s)Rate2 = [KMnO4]/time10.0108 0.629200.470.000053920.01080.629195.000.000055430.01080.629191.080.0000565
Average Rate ____________________
Standard dev. ____________________
95% conf., ? ____________________
Table : 4
T =oC__25___
Trial[KMnO4](M)[H2C2O4](M)time (s)Rate3 = [KMnO4]/time10.02170.315268.320.000080920.02170.315256.000.000084830.02170.315328.640.0000660Average Rate ____________________
Standard dev. ____________________
95% conf., ? ____________________
Determination of Reaction Order:
The results from the various pairs of experiments will now be combined to find X and Y. The conditions for Experiments #1 and #2 differ by the oxalic acid concentration, [H2C2O4]. We can therefore use Eqn. 4 to give the reaction order with respect oxalic acid:
Reaction Order Data:
Reaction Order X (rounded to nearest 10th) Reaction Order Y (rounded to nearest 10th) Overall Order of Reaction X Y Rate constant, k (with proper units)
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Results