GTPase switch proteins

a. are active when bound to GDP but inactive when bound to GTP.

b. are active when bound to GTP but inactive when bound to GDP.

c. are converted from the inactive to active state by a guanine nucleotide exchange factor (GEF).

d. synthesizes GTP from GDP.

#Question id: 173

#Unit 1. Molecules and their Interaction Relevant to Biology

What is the net charge on the tripeptide Gly-Arg-Lys at pH 7? The table below gives the pKaʹs of the ionizable groups on the free amino acids.

#Question id: 174

#Unit 1. Molecules and their Interaction Relevant to Biology

What is the net charge on the dipeptide Arg-Pro at pH 9.0? The table below gives the pKaʹs of the ionizable groups on the free amino acids.

#Question id: 175

#Unit 1. Molecules and their Interaction Relevant to Biology

The ionic charges associated with a protein molecule are ________.

#Question id: 176

#Unit 1. Molecules and their Interaction Relevant to Biology

A peptide has the sequence Glu–His–Trp–Ser–Gly–Leu–Arg–Pro–Gly. What is the net charge of the molecule at pH 3

#Question id: 176

#Unit 1. Molecules and their Interaction Relevant to Biology

A peptide has the sequence Glu–His–Trp–Ser–Gly–Leu–Arg–Pro–Gly. What is the net charge of the molecule at pH 3

#Question id: 177

#Unit 1. Molecules and their Interaction Relevant to Biology

The titration curve of alanine shows the ionization of two functional groups with pKa values of 2.34 and 9.69, corresponding to the ionization of the carboxyl and the protonated amino groups, respectively. The titration of di-, tri-, and larger oligopeptides of alanine also shows the ionization of only two functional groups, although the experimental pKa values are different. The trend in pKa values is summarized in the table. Which of the following is a reason for this shift in pK values