Biotech & Techniques MCQ - Biotechnology Engineering (BT) MCQ

The recognition site for EcoRI restriction site is GAATTC

In given all four options
 is the palindromic sequence because sequence same from both side in both strands.

In plant tissue culture if

Met-Trp-Cys-Trp is the best choice for reverse translation into a DNA sequence because it contains fewer amino acid residues having multiple codon. Trp, Met have one codon each and cys has two, while Leu and Arg each have dic codon. 

• Footprinting (A): This technique, often referred to as "DNase footprinting," is used to study the binding sites of DNA-binding proteins such as transcription factors on DNA. So the appropriate match would be (T) Identification of binding sites of transcription factor.

• ChIP Assay (B): Chromatin immunoprecipitation (ChIP) assay is used to investigate the interaction between proteins and DNA in the cell. This technique can identify the binding sites of DNA-associated proteins, such as transcription factors, on the genome. Therefore, the match is (T) Identification of binding sites of transcription factor.

• ELISA (C): The enzyme-linked immunosorbent assay (ELISA) is a test that uses antibodies and color change to identify a substance. It is commonly used for the detection and quantification of proteins, including hormones and antibodies. Thus, the match would be (S) Quantification of transgene expression if referring to a protein product of a transgene.

• Gel Filtration Chromatography (D): This is a type of size exclusion chromatography that separates proteins based on their size, and it's often used for molecular weight determination. Therefore, the match is (R) Molecular weight determination.

So, the matches are:

• (A) Foot printing - (T) Identification of binding sites of transcription factor
• (B) ChIP Assay - (T) Identification of binding sites of transcription factor
• (C) ELISA - (S) Quantification of transgene expression
• (D) Gel Filtration Chromatography - (R) Molecular weight determination

Chaotroph is a term used for agents such as urea that lead to denaturation and precipitation of biomolecules by enhancing solvent-solvent interactions and reducing solvent-solute interactions.  

In Maxam-Gilbert method of DNA-sequencing, the first nucleotide at 5’ can not be sequenced. So it requires sequencing of both the strand of DNA.

Application of monoclonal antibody in the biosensors is a diagnostic application of maps. Using in transplant rejection and infectious disease is the therapeutic application of monoclonal antibodies. Purification of drugs and imaging the target is the clinical application of monoclonal antibody.

Proteins have least density around 1.55 g/cm3, followed by DNA (1.7) and maximum by RNA (1.8). Among linear and supercoiled DNA, EtBr binding is more in linear hence its density is lower than supercoiled.

The Sangers gels are read from bottom to top to obtain a sequence of DNA. however this is the sequence of newly synthesized strand and template is complementary to this. On reading the gel from bottom we get 5 -TGC'AT-3 '. while complement ary to this would be 3’ACGTA5’, which can be written from 5’to 3’ as 5’ATGCA3’.

The probability of restriction site in a given DNA is calculated by formula
One in 4ⁿ, where n is the number of base pairs in a site
i.e. one site in 4096 bp,hence a DNA of size 4361 is likely to possess only one site based on random probability 

Chymotrypsin cleaves at C terminal of aromatic amino acids but these amino acids should not be followed by proline.

A change in protein molecular weight is reflected as shift in band position which may occur due to truncation or cleavage, while change in expression is reflected as intensity change of band.

Poly His can effectively bind with Ni column and helps in purification, while GFP or green fluorescent markers help in determining expression. Smallpox and adenovirus are commonly used for cloning and expression but, after removing the genes for pathogenicity.

Restriction enzymes are not synthesized by mammals but they form immune defence of bacterial cells. It is however true that every restriction site is palindromic, read same from both the ends. Two restriction enzymes can cut at same sites like isoschizomers. Also, there are three prominent classes of restriction enzymes, type I which cut 1000 bp away from recognition sites, type II which cut within the recognition sites, and type III which cut approximately 50 bp away from recognition sites, hence statement 1 is not correct.

Trypsin cuts at the C terminal of Lys or Arg but next a.a. should not be proline. And, also it is an endonuclease not exonuclease. So 2 fragments will be generated.