Exam Two Questions Flashcards
(17 cards)
Which type of spectroscopy, fluorescent or non fluorescent, emits more heat after absorption of electromagnetic radiation?
Non fluorescent spectroscopy emits more heat after absorption because fluorescent light will emit energy as light and not heat
Which is used in emission spectroscopy, visible or fluorescent light?
Fluorescent light is used in emission spectroscopy because visible light will be absorbed and not re-emitted
Which type of cuvette, quartz or plastic, does not absorb UV light?
Quartz cuvettes do not absorb UV light and because of this they are used when measuring absorbance with the UV light spectrum
Which color light, red or blue, contains a greater level of energy?
Blue light has more energy because it has a shorter wavelength - opposite correlation between wavelength and energy
How might choice of a protein standard for the Bradford method influence the results of the protein values?
A protein standard must be similar to the protein of interest in order to conduct an accurate standard curve
In an atom, what kind of energy transitions is allowed? What about in a molecule?
In an atom, energy transitions occur from lower to higher while in a molecule energy moves from higher to lower
List three different types of lipid solvent extraction and provide limitations and advantages for each method.
Goldfish: solvent vapor condenses on sample which releases fat
A: sample is constantly exposed to fresh solvent
D: channeling can occur
Soxhlet: combination of soaking and rinsing
A: most accurate method of solvent method, soaking and rinsing is simultaneous
D: only one sample can be done at one time
Soaking: leaving sample in solvent - fat will be extracted
A: long interaction time between sample and solvent
D: solvent may become saturated which will lower extractability
List at least three sources of non-protein nitrogen that could influence the percent protein measured in the product.
Caffeine, nitrates/nitrites, and theobromine
Draw a diagram that will show how the response will vary as a function of the amount of peanut left behind on the processing equipment.
The response should remain constant then go down and level out as amount increases - sinusoidal curve
Diagram a generalized antibody showing the FAB and the FC portions and indicate where the antigen will attach.
The FC is the lower end while the FAB is the upper two regions and that is where binding occurs
You have noticed that the surface to be tested for allergen is heated but not washed. The immunoassay indicates there is no peanut protein left behind. What might this tell you about the epitope that is being targest by the assay?
Since the immunoassay results are negative after heating it could be that the epitope is conformational since heat could damage the 3D structure. This means the antibody will not be able to recognize the damaged epitope of that antigen - negative result
Describe how you would produce an antibody to detect an allergen.
- Expose antigen to an animal cell to stimulate antibody production of interest
- Extract the antibody producing animal cells and combine with a cancerous cell to form a hybridome and further stimulate antibody production
- Keep doing this until you’ve got enough antibodies then purify the sample
Diagram a typical flow through the lab for conducting a proximate analysis of chocolate. For each component indicate at least two methods that could be employed for analysis.
- Moisture content
Remove water through drying (Fischer titration or dehydration) - Fat content
Remove fat using the Soxhlet or Babcock method - Protein content
Analyze protein with Bradford or Dumas assay - Ash analysis
Remove organic compounds through wet or dry ashing - Carbohydrate analysis
Calculate the amount of carbohydrates using the phenol/sulfuric acid assay or subtract the other macronutrients from the total to get carb. content
How could you use gel electrophoresis to separate proteins with the same molecular weight?
To separate proteins with matching molecular weights you could use isoelectric focusing to help differentiate them since it is not based on molecular weight but isoelectric point
Which carbons is most likely to be initiated in lipid oxidation?
The chiral carbon’s hydrogen is most likely to be taken away by a free radical
Why is it important to predry samples for lipid analysis?
It is important to predry samples for lipid analysis because water dilutes the solvent and acts as a barrier between the sample/solvent. Drying leads to more solvent/sample interactions which also results in better extractability
What is the principle of a Babcock fat analysis of milk? If you were analyzing a sample of milk, what would be the effect of having the temperature of the milk below the recommended?
The principle of the Babcock method is the use of sulfuric acid to generate heat, denature proteins, and release fat in the sample. With the help of centrifugation the fat can be further separated due to its lighter density. If the sample was below recommended temperature you face the risk of the fat solidifying which will lead to inaccurate results
