61 Questions
What is the main objective of the practical on estimation of protein concentration?
To estimate the relative number of peptide bonds in different proteins
Why is accurate protein concentration determination important in biochemical molecular research?
For all aspects of biochemical molecular research
What is the primary method of protein determination used in the practical?
The Biuret reaction
How many principal methods of protein determination are there?
5
What is the weight of albumin used as a 'standard' protein in the practical?
5 mg
Why is the completion of the test on Blackboard important?
To prepare for the other practicals in the module
What is proteinuria used for in biological samples?
To detect kidney malfunction
What is the purpose of estimating protein content in plasma derived from blood?
To determine the protein content of plasma
What is the minimum number of peptide bonds required for the Biuret reaction?
2
What is the significance of peptide bonds in protein determination?
To estimate the relative number of peptide bonds
Why is this practical not assessed?
Because it is a preparatory practical for other assessed practicals
What is the primary limitation of protein assays that depend on the reactions of individual amino acids?
They are influenced by the variation in amino acid composition of proteins
What is the purpose of adding Folin Ciocalteau's reagent in the Lowry method?
To enhance the Biuret reaction
What is the general percentage of nitrogen in proteins?
16%
Why is the nitrogen content method frequently used for solid samples?
Because it can cope with insoluble samples
What is the wavelength of ultraviolet absorption used to estimate protein concentration?
280 nm
What is the primary advantage of the dye-binding method?
It does not react with free amino acids
What is the purpose of wearing gloves and safety spectacles in the laboratory?
All of the above
What should you do in case of skin or eye contamination?
Rinse with lots of water and inform a demonstrator
What is the purpose of the Accident Book in the laboratory?
To report accidents and near-misses
Why is it important to dispose of waste chemicals properly at the end of the practical?
To prevent contamination
What is the primary purpose of using a new pipette tip for each separate solution?
To prevent contamination of the Biuret reagent
What is the total volume in each tube after adding 4 ml of Biuret reagent?
5.0 ml
What is the purpose of leaving the mixture for 20 minutes before measuring the absorbance?
To allow the Biuret reagent to react with the proteins
What is the unit of measurement for the protein concentration on the x-axis of the graph?
mg per ml
What is the purpose of adjusting to zero absorbance using the contents of Tube 1 as the blank and reference solution?
To eliminate the background interference in the measurements
What is the equation of the line of best fit used for?
To estimate the concentrations of protein in the casein, gelatin, and plasma solutions
What is the purpose of using the contents of Tube 1 as the blank and reference solution?
To adjust to zero absorbance
What is the wavelength at which the absorbance is measured in the spectrophotometer?
550 nm
What is the concentration of the albumin solution in Tube 1?
0 mg/ml
How should the results of the plasma solution be expressed?
mg protein per ml of undiluted plasma
What is the primary purpose of estimating protein content in plasma derived from blood in this practical?
To compare with the standard protein albumin
What is the minimum number of peptide bonds required for the Biuret reaction?
Two
Why is accurate protein concentration determination important in biochemical molecular research?
For all aspects of biochemical molecular research
What is the significance of peptide bonds in protein determination?
They are used to estimate protein concentration
What is the importance of completing the test on Blackboard?
To help the student prepare for other practicals in the module
What is the purpose of using 5 mg of albumin as a 'standard' protein?
To compare with other proteins
Why is protein estimation important in biological samples?
For determining the amount of enzyme in a solution
How many principal methods of protein determination are there?
Five
What is the focus of this practical?
Comparing the relative number of peptide bonds in casein and gelatin
Why is this practical not assessed?
Because it is a preparation for other practicals in the module
What is the molarity of the sodium hydroxide solution added to the biuret reagent?
1M
What is the purpose of vortexing the mixture in each tube?
To create a homogeneous mixture for spectrophotometric analysis
What is the unit of measurement for the y-axis of the graph?
Absorbance units
What is the primary advantage of using a calibration curve?
To determine the concentration of proteins in unknown samples
What is the purpose of adding 4 ml of biuret reagent to each tube?
To initiate the biuret reaction
What is the primary assumption underlying the estimation of protein concentration in plasma?
The protein concentration is directly proportional to the absorbance
What is the purpose of plotting a graph in Excel?
To create a calibration curve
What is the significance of the 20-minute waiting period before measuring the absorbance?
To allow the biuret reaction to reach equilibrium
What is the purpose of using a disposable pipette tip for each separate solution?
To prevent cross-contamination between solutions
What is the primary application of the biuret reaction in biochemical research?
To estimate protein concentration in biological samples
What is the primary advantage of using the nitrogen content method for protein estimation?
It can cope with insoluble samples
What is the main limitation of the Biuret reaction?
It is influenced by free amino acids
Why is the Lowry method more sensitive than the Biuret reaction?
It is enhanced by Folin Ciocalteau's reagent
What is the purpose of using a heavy metal in protein estimation?
To separate proteins from non-protein nitrogenous substances
What is the primary limitation of ultraviolet absorption method for protein estimation?
It is influenced by the amino acid composition of proteins
What is the purpose of wearing gloves and safety spectacles in the laboratory?
To protect the skin and eyes from chemicals
What is the primary advantage of the dye-binding method?
It is not influenced by free amino acids
What is the primary purpose of using a fume cupboard in the laboratory?
To contain hazardous vapours
What is the primary limitation of methods that depend on the reaction of individual amino acids?
They are dependent on the amino acid composition of proteins
What is the purpose of containing liquid spills with a towel roll in the laboratory?
To contain hazardous chemicals
This practical aims to estimate the relative number of peptide bonds in casein, gelatin, and albumin, and determine the protein content of plasma. Accurate protein concentration determination is crucial for biochemical molecular research.
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