Q1. During the process of solubilisation of proteins, Dithiothreitol and -Marcap
ID: 141741 • Letter: Q
Question
Q1.
During the process of solubilisation of proteins, Dithiothreitol and -Marcaptoethanol are used in order to:
Select ONE answer:
A. Reduce the disulphide bonds present between and within protein chains
B. Act as denaturing agents
C. Both a and b
D. None of these
Q2.
High amount of salts is present in many biological samples. They are generally removed by:
Select ONE answer:
A. Spin dialysis and Dialysis
B. Gel filtration
C. Buffer exchange
D. All of the above
Q3.
Nucleic acids are generally removed during the sample preparation of proteins. Which of the following statement is NOT correct for nucleic acid contaminants?
Select ONE answer:
A. They can bind to proteins through electrostatic interactions
B. They enhance the sample viscosity and cause background smearing
C. Higher molecular weight nucleic acid can clog gel pores
D. They don’t interfere with proteins in gels because of their higher molecular weight
Q4.
During protein sample preparation by TRIzol method, the sample is divided into three different layers. What of the following is correct for those layers?
Select ONE answer:
A. Pink – DNA, White -Protein, Transparent-RNA
B. Pink - Protein, White - DNA, Transparent-RNA
C. Pink- RNA, White - protein, Transparent- DNA
D. Pink- Protein, White- RNA, Transparent- DNA
Q5.
Bradford assay is commonly used to quantify the protein concentration in a protein sample. Which of the statements given below is NOT correct for the Bradford assay?
Select ONE answer:
A. The assay is based on the absorbance shift of Coommassie brilliant blue dye.
B. Red form of the dye is converted into its blue form under acidic conditions.
C. Absorbance is always measured at 280 nm.
D. Bradford assay is based on Beer Lambert law.
Explanation / Answer
1.both A and B.
Dithiothreitol and -Marcaptoethano denature and cleaves the disulphide bond between thiol groups of many protein such as cystine.
2.gel filtration
small molesules and salt are removed by processo of gel filteration. buffer exchange anddialysis are methods to separate soluble macromolecules.
3.d.
polysaccharides, nucleic acids, lipids, phenolic are o high molecular weight polysaccharides.athese compouns can clog grl pores,reduce viscotity.
4.c.Pink- RNA, White - protein, Transparent- DNA
during protein preperation RNA is in upper phase(layer) and Protein inmiddle and DNA in lower phase.
5.b.Red form of the dye is converted into its blue form under acidic conditions.
binding of Coomassie dye under acidic conditions results in a color change from brown to blue.
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