Final Flashcards
Which is the method that does not use copper ions to bind to protein components for estimating proteins?
Bradford Assay
For measuring bacterial growth, cell density is measured by what principle?
Scattering light at 600nm by the bacterial cells
What is the concentration of RNA with an A260 of 0.85 using a path length of 0.5 cm?
68.0 micrograms/mL
The stock solution of fluorescein (molecular weight 332.31 g/mol) is 5 mg/mL. What is the volume of stock solution is needed to make 2 mM solution of fluorescein in a total volume of 3.0 mL?
5g/L * mol/332.31g * x = 2 mM * 1M/10^3 mM * 3 mL= 400 microliters
The standard curve (absorbance (Y) vs amount in micrograms protein (X)) of Bradford assay for protein BSA is y=0.0536x+0.0026. The absorbance of 10-fold diluted test sample is 0.17, what is the concentration in the starting undiluted sample?
10*.17 = 0.0536 x + 0.0026
X=31.2 micrograms/mL
The frequency of wave A is 20/s, while that of wave B is 35/s. Which of the waves will have the highest energy?
Wave B
A 10 mg acetylsalicylic acid (aspirin) dissolved it in 1 mL volume has absorbance (with a 1 cm path length) as 0.1. If the molecular weight of 180.16 g/mol, what is the molar extinction coefficient?
10g/L*mol/180.16 = 0.0555062167 M = C E = .1/0.0555062167 = 1.8/ (M * cm)
Which set of the following amino acids are all polar? FKQ HMN DNR MTE PCS
DNR
A amino acid contain two carboxyl groups (pKa of 2.19 and 4.35) and one amino group (pKa 9.8). What is the pI?
3.22
You have a ten nucleotide (nt) long DNA in a double stranded (ds) form, single stranded (ss) from, and the same ten nucleotides free in the solution. Assume the nucleotides to be composed of three adenine, two guanine, two cytosine, and three Thymine. You determined the absorbance of the DNA and nucleotides at 260 nm. Which of the following represents the absorbance of the different reagents in the order of increasing absorbance?
Ss DNA, ds DNA, free nt Ds DNA, ss DNA, free nt Free nt, ds DNA, ss DNA Ds DNA, free nt, ss DNA None of the above
Ds DNA, ss DNA, free nt
What is the overall charge of the peptide GVARGLMPQVNGDKLWQILN at pH 7?
+1
You have titrated a compound and measured the absorbance, which changes depending on the protonation, versus the pH. You use the linear derivation of the HH and get the following equation for the line. Based on this, what is the pKa?
Log (Aa-Aobs)/(Aobs-Ab)=pH-pKa
Y=0.9177x-6.3555
6.4
A mixture of the proteins urease (pI 4.0), Beta-lactoglobulin (pI 6.2), and hemoglobin (pI 8.8) need to be purified at pH 7.5 buffer on an anion exchange column. What is the order of elation of the three protein?
Hemoglobin, Beta-lactoglobulin, urease
In the above question, which among the 3 proteins can elute in the equilibrium buffer without having to increase the salt concentration?
Hemoglobin
You have carried out a gel filtration purification using a column with a Vo of 12 mL and a Vt of 56 mL. The Kav for the largest protein and the smallest protein are: Protein Ve A. 42 mL B. 18 mL C. 12.5 mL D. 31 mL
0.01 for largest; 0.68 for smallest
The histidine sidechain in an enzyme active site has a pKa of 6.8. About what percent of the histidine side chains are ionized at pH = 6.96?
40%
How will you prepare 100 mL of a 10% (v/v) solution of Triton detergent from a stock of 50%?
Add 20 mL of 50% Triton and 80 mL water
Which of the following represents an elation with the most shallow gradient for the choices given?
From 100 mM NaCl to 1 M NaCl in 0 mL
From 100 mM NaCl to .5 M NaCl in 100 mL
From 100 mM NaCl to 1.5 M NaCl in 100 mL
From 100 mM NaCl to 1 M NaCl in 100 mL
From 100 mM NaCl to .5 M NaCl in 100 mL
The Bradford assay works via what principle?
Coomassie reagent binding all proteins non-specifically
Which of the following is an amphoteric substance?
A. Carbonic acid B. Carbonate ion C. Bicarbonate ion Both A and B Both B and C
C. Bicarbonate ion
Which of the following chromatography methods use isocratic elation to elute the adsorbed material from the column?
Size Exclusion Chromatography
Anion Exchange Chromatography
Cation Exchange Chromatography
None of the above
Size Exclusion Chromatography
You need to separate a mixture of proteins with the following characters: Protein A: 40 kDa protein that dimerizes in solution, pI of protein A is 6; protein B: 50 kDa, with a pI of 6.5: and protein C: 120 kDa with a pI of 5.6. Choose the best choice from the following options to purify a mixture of these proteins. The component proteins can be separated as a flow through from a column or as elations after binding a column. (The procedure selected should have proteins A, B, and C as finely resolved as possible using the list of choices below.) What is the order of the proteins?
Sephacryl S-200 (fractionation range 5000-250000) order, C, A, B
Sephacryl S-200 (fractionation range 5000-250000) order, C, B, A
Sephardex S-75 (fractionation range 3000-250000) order C, B, A
Anion Exchange column (proteins in Tris buffer pH 7) order C,A, B
Cation Exchange column (proteins in Tris buffer pH 7) order C,B, A
Sepharcryl S-200 order C,A, B
If a person mixes 70.0 microliters of sample with 1330 microliters of dH2O, then they will have made a ___ fold dilution.
20
1400/70
If a person wanted to make a 60 fold dilution of a stock solution into a total volume of 300 microliters, then how many micro liters of stock solution would they require?
5 microliters
300/60