Precision will be reduced, but yield will be increased

Optimisation of a PCR reaction is often a compromise between the competing demands for precision, efficiency and yield. Although the specific effects may vary, generally, increasing the annealing temperature will increase non-specific primer binding and reduce precision. Increasing the length of the elongation phase will reduce the proportion of incomplete newly-synthesised strands and therefore increase yield. In this case, the potential effect on efficiency is unclear. Increasing the elongation phase would increase the reaction time, but the time taken to ramp down to a lower annealing temperature would be reduced.

Which of the following true about real time PCR?

#Question id: 725

#Part-B Specialized Branches in Biotechnology

At 25°C values of [θ]222, the mean residue ellipticity at 222 nm, are - 33,000 and -3,000 deg cm2 dmol-1 for a polypeptide existing in α- helical (α) and β-structure (β), respectively. If this polypeptide undergoes a two-state heat-induced α-β transition, and a value of [θ]222 =  -15,000 deg cm2 dmol-1 is observed at 60°C, then this observation leads to the conclusion that the α helix conversion to β- structure is:

#Question id: 727

#Part-B Specialized Branches in Biotechnology

26-residue peptide composed of alanine and leucine shows a circular dichroism (CD) spectrum characteristic of α-helix at 50°C in 5 mM phosphate buffer at pH 7.4. When the peptide solution is cooled gradually to 25°C, and the CD spectra are recorded at different temperatures, the most likely observation will be that

#Question id: 729

#Part-B Specialized Branches in Biotechnology

Which of the following is correct about the collagen triple-helix domain

a. is rich in glycine.                             b. is rich in proline.

c. is rich in hydroxyproline.                d. is an alpha helix.

#Question id: 732

#Part-B Specialized Branches in Biotechnology

Ramachandran plots can help increase the accuracy of models derived from x-ray crystallography data. The plot below was created by measuring phi, and psi for each amino acid residue in a 2.2 A resolution crystal structure. In the plot, which excludes Gly and Pro residues, selected residues (dots) are numbered 1 through 5.

Which of the following statements can be correctly stated for this plot in reference to selected residues?

A. Residues 1 and 3 are in either B sheets

B. residue 2 is in a right-handed a helix, and residue 4 is in a left-handed a helix.

C. If residue 5 were Gly, it might be in an acceptable position in the plot

#Question id: 734

#Part-B Specialized Branches in Biotechnology

Which of the following statements is true for two different tripeptides consisting of either glycine or proline?

#Question id: 736

#Part-B Specialized Branches in Biotechnology

The most important contribution to the stability of a protein’s conformation appears to be the: