User:Eric Martz/Ramachandran Principle Quiz

1 How many bonded atoms are required to constitute a dihedral (torsion) angle, such as phi or psi?

	None
	1
	2
	3
	4
	5

2 The number of phi and psi angles in an isolated amino acid (not in a polypeptide chain) is:

	None
	1
	2
	3
	4
	5

3 The number of atoms held into a geometric plane by a peptide bond is:

	3
	4
	5
	6
	7
	8

Questions below may have more than one correct answer.

4 Phi and psi angles directly determine

	Primary structure.
	Secondary structure.
	Tertiary structure.
	Quaternary structure.

5 Alpha helices are compatible with

	All possible phi-psi angle combinations.
	A limited range of phi-psi angle combinations.
	A limited range of phi angles with all possible psi angles.
	A limited range of psi angles with all possible phi angles.

6 Common secondary structures are energetically favored because

	They optimize main-chain hydrogen bonds.
	They represent all possible conformations.
	They maximize clashes between atoms.
	They minimize clashes between atoms.

7 Overlap of van der Waals radii

	Between two non-bonded atoms is called a clash.
	Between two covalently bonded atoms is called a clash.
	Occurring between two non-bonded atoms in a molecular model signifies an energetically favorable interaction.
	Is physically impossible between two non-bonded real atoms.

8 In a Ramachandran plot, the dots cluster

	Where clashes occur.
	Where clashes do not occur.
	Where alpha helices occur.
	Where beta strands occur.
	Where neither alpha helices nor beta strands occur.
	Where the phi and psi angles are energetically favorable.