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Written Sample Laboratory Exam Questions…….
1. You are given a sample of that contains 2800 ul, how much does it weigh?
2. Describe how you make a 75 mM solution of Tricine solution (Tricine MW = 179g)
3. Assume you have a solution of 200 mL of 5 M NaCl. How would you prepare 1.5 M NaCl? How
would you prepare 0.5M NaCl? How would you prepare 0.1M NaCl? How would you prepare 75
mM NaCl?
4. Assume you have a solution of 200 mL 3 M NaCl. Will you be able to prepare 400 mL of 2 M
NaCl. Please explain your answer.
5. You are given a 3 M solution of HCl. For an experiment you are about to perform you need 3 mls
of .5 M HCl. How much of the 3M solution will you use? How much water will you use?
6. When using the 100X objective on the microscope, you should use a) water b) wright’s stain c)
immersion oil d) mannitol assay buffer e) secondary antibody
7. Follow through the following cell fractionation protocol explain what is happening at each step:
Use a razor blade to remove the outer 2 mm of the
cauliflower surface
Grind the tissue in a chilled mortar with a chilled pestle
and chilled reagent grade sand and mannitol grinding
medium
Filter the suspension through cheesecloth
Centrifuge the filtrate at 600 X G
Decant the supernatant and centrifuge the supernatant
Why is everything chilled? Why is sand used?
Why is mannitol grinding medium used?
What is accomplished at this stage?
Why is this speed used? What is in the pellet?
What is in the supernatant?
7. What is the role of the SDS when running an SDS-PAGE gel?
8. Answer based off the image of the gel below
Shown above is a picture of an SDS-gel. The molecular weights of the protein standards (Outside lanes)
are as follows: lysozyme, 14,300; lactoglobulin, 18,400; carbonic anhydrase, 29,000; ovalbumin, 43,000;
bovine serum albumin, 68,000; phosphorylase B, 97,400; myosin, 200,000. Rulers are available from the
instructor.
What is the molecular weight of protein standard B?
Determine Rf for protein standard E and for band Z.
9. You want to spin a sample at 1000 x g (RCF) in the Beckman Centrifuge using the JA-20 rotor. What
speed will you centrifuge your sample? Note the radius of the JA-20 rotor is Rmin = 3.2 cm, Ravg = 7.0 cm
and Rmax = 10.8 cm
10. Name all the components in the relative centrifugal force equation. (RCF = 1.119 x 10-5 (rpm)2 r)
11. Draw a diagram of a cross-section of a rotor, the axis of rotation and the location of the centrifuge
tubes. Determine where Rmin and Rmax are? Are the forces along the centrifuge tube the same
throughout?
12. Describe how Wright’s stain works, and what parts of the cell it stains, and what color each part stains.
13. When looking at your erythrocytes under a microscope, and found the diameter to be .12 mm. Given
that the cell is roughly spherical, determine the volume of the cell. (Hint determine volume-which will get
you to cubic cm. remember 1 cubic cm is equal to 1 mL. Convert to mL then to ul)
14. You wish to synthesize a 30 ml of 10 mM NaCl. Starting with NaCl crystals and water, what will you
do? (Hint: You may find out that the amount you have to weigh out is too small. How will you deal with
this?
15. Define the terms Vmax and Km in detail. When studying a Lineweaver-Burke plot how is the Vmax
and Km determined?
16. Tyrosinase is an enzyme that catalyzes a series of reactions involved in tyrosine metabolism. Below are
the reactions. Place the word tyrosinase above the arrows of the reactions that tyrosinase catalyzes. Circle
the reaction which we used to determine tyrosinase activity in the laboratory. In the reaction we performed
in the laboratory, what is the substrate, and what is the product. Pls. note the color of each the substrate and
product, as well as how we measured the formation of product.
17. From the western blot protocol, what protein does our primary antibody recognize? What does the
secondary antibody recognize?
18. What is the purpose of the milk in the Western Blot Protocol and why is it necessary?
19. Please explain the purpose of the SDS in the transfer of the proteins from the gel to the membrane.
20. From the immunofluorescence protocol, what protein does our primary antibody recognize? What does
our secondary antibody recognize?
21. In what organism was the primary antibody produced for immunofluorescence? In what organism was
the secondary produced? Please explain how the primary antibody was produced.
22. Please state the total magnification if you were using the . A) using the 10X objective B) 40X objective
C) 100 C objective
22. For the laboratory practical part of the exam, you will be asked to pipet accurately using the 100-1000ul
pipet and the 10-100 pipet.
23. For the laboratory practical part of the exam, you will be asked to use the spectrophotometer. Be sure to
know the difference between the blank and experimentals.