When sufficient heat is applied, double-stranded DNA denatures into two single-stranded molecules as the heat breaks all of the hydrogen bonds. In an experiment, molecules of single-stranded DNA from species X are separately hybridized with putatively homologous single-stranded DNA molecules from five species (A-E). The hybridized DNAs are then heated, and the temperature at which complete denaturation occurs is recorded. Based on the data below, which species is probably most closely related to species X?

#Question id: 741

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of following statements are INCORRECT about secondary structure of proteins

A. Long block of Glu residues segment of the chain will not form an alpha helix at pH 7.0 but it ll take helical confirmation below its pKR value

B. Long block of Lys residues segment of the chain will not form an alpha helix at pH 7.0 but it ll take helical confirmation above its pKR value

C. Long block of Ala residues segment of the chain will not form an alpha helix at pH 7.0 but it ll take helical confirmation below its pKR value

D. Histidine side chain remain uncharged over pH range 3-6

#Question id: 740

#Unit 1. Molecules and their Interaction Relevant to Biology

The conformation of the backbone of a polypeptide is described completely by the angle(s) of rotation about which bond(s)?

#Question id: 739

#Unit 1. Molecules and their Interaction Relevant to Biology

What is true about the rotation about bonds in a protein backbone?

#Question id: 738

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following is correct for peptide bonds

A) C and N are shorter than typical C-N bonds.

B) C and N are longer than typical C-N bonds.

C) C and O are longer than typical C=O bonds.

D) C and O are shorter than typical C=O bonds.

#Question id: 737

#Unit 1. Molecules and their Interaction Relevant to Biology

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

#Question id: 736

#Unit 1. Molecules and their Interaction Relevant to Biology

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