Chiral Centres in Penicillin:
Chiral centres are carbon atoms in a molecule that have four different groups attached to them, leading to the molecule having non-superimposable mirror images known as enantiomers. In the case of penicillin, there are 3 chiral centres present.

Structure of Penicillin:
- Penicillin is a beta-lactam antibiotic composed of a beta-lactam ring and a side chain.
- The beta-lactam ring contains the chiral centres.

Chiral Centres in Penicillin:
- The beta-lactam ring in penicillin has 3 chiral centres, each represented by a carbon atom with four different substituents attached.
- These chiral centres contribute to the stereochemistry of penicillin, affecting its biological activity and interactions with enzymes.

Importance of Chiral Centres:
- Chirality plays a crucial role in the pharmacological properties of drugs like penicillin.
- Enantiomers of drugs can have different pharmacological activities, with one enantiomer often being more effective or causing fewer side effects than the other.
Therefore, the presence of 3 chiral centres in penicillin is important for understanding its stereochemistry, pharmacological properties, and interactions within the body.