You have isolated two temperature-sensitive mutations in phage l that you suspect may be in the same gene. These phage mutants are called ts-1 and ts-2. Each mutant will form plaques at 35˚C but not at 42˚C. You cross ts-1 to ts-2 phage by coinfecting E. coli at the permissive temperature of 35˚C. When the resulting phage lysate is plated at 35˚C you count 10,000 plaques per ml of phage lysate, but when the same phage lysate is plated at 42˚C, there are only 80 plaques per ml.           What is the distance between the ts-1 and ts-2 mutations in m.u.?

#Question id: 729

#Unit 1. Molecules and their Interaction Relevant to Biology

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: 731

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following structure is mentioned in the given Ramachandran plot

#Question id: 732

#Unit 1. Molecules and their Interaction Relevant to Biology

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: 733

#Unit 1. Molecules and their Interaction Relevant to Biology

Which one of the statements on protein conformation, detailed below is INCORRECT?

#Question id: 734

#Unit 1. Molecules and their Interaction Relevant to Biology

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

#Question id: 735

#Unit 1. Molecules and their Interaction Relevant to Biology

The a-keratin chains indicated by the diagram below have undergone one chemical step. To alter the shape of the a-keratin chains—as in hair waving—what subsequent steps are required?