Understanding Stereochemistry and Fischer Projections

What is the main difference between R/S and D/L configurations?

• R/S is used for sugars, D/L is used for amino acids.

• R/S and D/L are used interchangeably.

• R/S is for 3D structures, D/L is for flat projections.

• R/S is for flat projections, D/L is for 3D structures.

Which atom is always assigned the lowest priority in the Cahn-Ingold-Prelog system?

• Carbon

• Oxygen

• Nitrogen

• Hydrogen

What is the priority order of atoms in amino acids according to the Cahn-Ingold-Prelog system?

• N-O-S-C-H

• H-C-N-O-S

• S-N-O-C-H

• O-N-C-H-S

In a Fischer projection, if the amine group is on the left, what configuration does the amino acid have?

• L

• D

• S

• R

What is the configuration of L-Cysteine according to the R/S system?

• L

• S

• R

• D

Which amino acid is an exception to the rule that all L-amino acids are S?

• Alanine

• Cysteine

• Valine

• Tyrosine

What is the first step in converting a 3D structure to a Fischer projection?

• Draw the carbonyl at the top

• Guess the configuration

• Visualize the structure

• Rank the substituents

What is the configuration of D-Glutamate in the R/S system?

• D

• S

• R

• L

Which method is NOT mentioned for converting structures?

• Bonus trick

• 3D visualization

• Using a computer program

• Guess and check

What is a zwitterion?

• A molecule with both positive and negative charges

• A molecule with only negative charges

• A molecule with no charge

• A molecule with only positive charges