Stereochemistry and Functional groups Flashcards
(16 cards)
Why is stereochemistry important
Because a molecule’s 3D shape determines its function and biological interactions; different isomers have different biological properties; it’s crucial for drug discovery and action.
What are isomers?
Molecules with the same number and kinds of atoms but different bonding patterns.
What are stereoisomers?
Isomers that differ in the spatial arrangement of atoms and are non-superimposable mirror images (chiral).
What is chirality?
A property where a molecule cannot be superimposed on its mirror image by any rotation.
What are enantiomers?
Isomers that are mirror images of each other.
What are diastereomers?
Isomers with more than one chiral center that are not mirror images.
What are epimers?
Isomers that differ at only one chiral center.
Why is there no isomerism with single bonds?
Because of free rotation around single bonds.
Why do double bonds show isomerism?
Because they restrict rotation, fixing the molecule in place.
What are geometric isomers?
Molecules where atoms/groups are arranged differently across a double bond:
Cis: same side
Trans: opposite sides
What are anomers?
Cyclic monosaccharides (special epimers) that differ at the anomeric carbon.
What’s the difference between α and β anomers?
α (alpha): OH on anomeric C opposite to ring O (trans)
β (beta): OH on anomeric C same side as ring O (cis)
hat does “homochiral” mean in biology?
DNA/RNA
AMINO ACIDS
MONOSACCHARIDES
All known life uses only one chiral form:
DNA/RNA → D-chiral (right-handed)
Amino acids (proteins) → L-chiral (left-handed)
Monosaccharides → D-chiral (right-handed)
Why was thalidomide important in stereochemistry?
Its S-enantiomer was teratogenic (caused birth defects), highlighting why chirality matters.
What is a functional group?
A group of atoms that frequently occur in biomolecules and give specific chemical properties.
Examples of important functional groups?
Carbonyl (Aldehyde → Aldose; Ketone → Ketose)
Hydroxyl (in carbohydrates, fatty acids)
Carboxyl (amino acids)
Amino group (amino acids)
Phosphate group (DNA, ATP)
