Question

1. what is the main principle of the bradford assay?

a. measurement of protein fluorescence intensity
b. binding of coomassie brilliant blue dye to proteins
c. reduction of copper ions by peptide bonds
d. reaction of proteins with the folin - ciocalteu reagent

1. which color change occurs when the dye binds to proteins?

a. blue → red
b. brown → blue
c. yellow → brown
d. green → purple

1. what is the absorbance wavelength measured in the bradford assay?

a. 280 nm
b. 540 nm
c. 595 nm
d. 750 nm

1. the bradford assay is most sensitive in which protein concentration

range?
a. 0.001 - 0.01 μg/ml
b. 1 - 100 μg/ml
c. 100 - 1000 μg/ml
d. 1 - 10 mg/ml

1. which protein is commonly used as a standard in this assay?

a. hemoglobin
b. casein
c. bovine serum albumin (bsa)
d. lysozyme

1. what is the role of the standard curve in the bradford assay?

a. to measure enzyme activity
b. to calibrate the spectrophotometer
c. to relate absorbance values to known protein concentrations
d. to calculate molar extinction coefficients

1. when you do the graph of concentration of standards and absorbance,

which one is the independent variable?
a. absorbance
b. concentration

1. which amino acid residues contribute most to coomassie dye binding?

Explanation:

1. The Bradford assay is based on the binding of Coomassie Brilliant Blue dye to proteins.
2. When the dye binds to proteins, it changes from yellow to brown.
3. The absorbance wavelength measured in the Bradford assay is 595 nm.
4. The Bradford assay is most sensitive in the 1 - 100 μg/mL protein concentration range.
5. Bovine Serum Albumin (BSA) is commonly used as a standard in this assay.
6. The standard curve in the Bradford assay is used to relate absorbance values to known protein concentrations.
7. In a graph of concentration of standards and absorbance, concentration is the independent variable.
8. Arginine amino acid residues contribute most to Coomassie dye binding.

Answer:

1. B. Binding of Coomassie Brilliant Blue dye to proteins
2. C. Yellow → Brown
3. C. 595 nm
4. B. 1 - 100 μg/mL
5. C. Bovine Serum Albumin (BSA)
6. C. To relate absorbance values to known protein concentrations
7. b. concentration
8. Arginine