Current analysis indicates that less than 2% of the human genome codes for proteins. Based on the systems approach employed by the ENCODE project, what percentage of the genome is estimated to be transcribed at some point in at least one cell type?

#Question id: 732

#Unit 1. Structure and Function of Biomolecules

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. Structure and Function of Biomolecules

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

#Question id: 734

#Unit 1. Structure and Function of Biomolecules

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

#Question id: 735

#Unit 1. Structure and Function of Biomolecules

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?

#Question id: 736

#Unit 1. Structure and Function of Biomolecules

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

#Question id: 737

#Unit 1. Structure and Function of Biomolecules

Which structure below indicates the proper hydrogen-bonding pattern between amino acids in an α-helix? (Dashed lines represent the hydrogen bonds.)