+1-315-636-4485
+91 98151-74050 
This quiz contains multiple-choice problems on protein structure basics and structural visualization, protein structure comparison and classification.
The building blocks of proteins are __ naturally occurring amino acids, small molecules that contain a free amino group (NH2) and a free carboxyl group (COOH).
Ten
Twenty
Nine
Nineteen
The hydrophobic set of amino acids can be further divided into aliphatic and aromatic. True or false?
True
False
__ the smallest amino acid has a hydrogen atom as the R group.
Valine
Proline
Glycine
Threonine
Peptide formation involves two amino acids covalently joined together between the carboxyl group of one amino acid and the amino group of another. True or false?
True
False
A linear polymer of more than fifty amino acid residues is referred to as a
Dipeptide
Oligopeptide
Peptide
Polypeptide
Which of the following is incorrect about the stabilizing forces?
Protein structures from secondary to quaternary are maintained by noncovalent forces
They include electrostatic interactions and hydrogen bonding but not van der Waals forces
Electrostatic interactions are a significant stabilizing force in a protein structure
Electrostatic interactions occur when excess negative charges in one region are neutralized by positive charges in another region
Which of the following is not correct about the α-helices?
An α-helix has a main chain backbone conformation that resembles a corkscrew
Nearly all known α-helices are right handed, exhibiting a leftward spiral form
Nearly all known α-helices are right handed, exhibiting a rightward spiral form
In a right-handed helix, there are 3.6 amino acids per helical turn
Which of the following is not correct about the β-sheet?
A β-sheet is a fully extended configuration built up from several spatially adjacent regions of a polypeptide chain
Each region involved in forming the β-sheet is a β-strand
The β-strand conformation is pleated with main chain backbone zigzagging and side chains positioned on same sides of the sheet
β-strands are stabilized by hydrogen bonds between residues of adjacent strands
Which of the following is incorrect about coils and loops?
They are regular structures
They are irregular structures
Loops are often characterized by sharp turns or hairpin-like structures
If the connecting regions are completely irregular, they belong to random coils
Which of the following is incorrect about the Integral Membrane Proteins?
Membrane proteins exist in lipid bilayers of cell membranes
The exterior of the proteins spanning the membrane must be very hydrophobic to be stable
The exterior of the proteins spanning the membrane must be very hydrophilic to be stable
Most typical transmembrane segments are α-helices
Globular proteins are usually insoluble. True or false?
True
False
Which of the following is incorrect about x-ray crystallography?
In x-ray protein crystallography, proteins need to be grown into large crystals in which their positions are fixed in a repeated, ordered fashion
The protein crystals are illuminated with an intense x-ray beam
The x-rays are deflected by the electron clouds surrounding the atoms in the crystal producing a regular pattern of diffraction
The protein crystals are illuminated with an intense infrared beam
Which of the following is incorrect about NMR?
It stands for Nuclear Magnetic Resonance
NMR spectroscopy detects spinning patterns of atomic nuclei in a electric field
NMR spectroscopy detects spinning patterns of atomic nuclei in a magnetic field
Protein samples are labeled with radioisotopes such as 13C and 15N
One can search for a structure in PDB using the four-letter code or keywords related to its annotation. True or false?
True
False
In CATH, structural domain separation is carried out by
Manual comparison only
Computer programs only
Human expertise only
A combined effort of a human expert and computer programs
