(A) Lock and Key Mechanism of Enzyme Action: Concept:
The lock and key model explains how enzymes interact specifically with substrates to catalyze biochemical reactions.
Explanation:
- Proposed by Emil Fischer.
- The enzyme has a specific active site.
- The substrate fits exactly into this active site like a key fits into a lock.
Steps:
- Substrate binds to enzyme's active site.
- Enzyme-substrate complex is formed.
- Reaction occurs and products are formed.
- Products are released; enzyme remains unchanged.
Key Features:
- High specificity
- Enzyme not consumed in reaction
- Explains substrate selectivity
(OR) (B) Central Dogma of Molecular Biology: Concept:
The central dogma explains the flow of genetic information in living organisms.
Statement:
Steps: 1. Replication:
- DNA makes an identical copy of itself.
- Ensures genetic continuity.
2. Transcription:
- DNA is transcribed into messenger RNA (mRNA).
- Occurs in nucleus (eukaryotes).
3. Translation:
- mRNA is translated into protein at ribosomes.
- Amino acids are assembled into polypeptide chains.
Importance:
- Explains gene expression
- Basis of molecular genetics
- Foundation of biotechnology