Molecular Tools: Restriction Enzymes and Modifications

📋 Course Outline

1. Restriction Enzymes Types
2. Restriction Endonuclease Nomenclature
3. Restriction Enzyme Classification
4. Restriction Enzyme Cleavage
5. Restriction Enzyme Applications
6. Modification Enzymes
7. Phosphatases Functions
8. Methylases and Methylation
9. Ligases Mechanism
10. Polynucleotide Kinase Activity
11. RNase Types and Functions

📖 1. Restriction Enzymes Types

🔑 Key Concepts & Definitions

• Restriction Enzymes (Restriction Endonucleases): Enzymes that recognize specific DNA sequences (restriction sites) and cleave DNA at or near these sites. They are essential tools in genetic engineering.

• Exonucleases: Enzymes that hydrolyze nucleotides from the terminal ends (5’ or 3’) of DNA or RNA molecules, removing nucleotides sequentially from the ends.

• Endonucleases: Enzymes that recognize specific internal DNA sequences (restriction sites) and cleave phosphodiester bonds within the DNA molecule, creating fragments with either sticky or blunt ends.

• Type I Restriction Enzymes: Multifunctional enzymes with both restriction and modification activities, cleaving DNA approximately 1000 bp away from recognition sites, requiring ATP, SAM, and Mg²⁺.

• Type II Restriction Enzymes: The most widely used in laboratories; recognize palindromic sequences and cleave within or at the recognition site, requiring only Mg²⁺, and do not need ATP. They produce predictable sticky or blunt ends.