Restriktioentsyymejä

Restriktioentsyymejä, or restriction enzymes, are proteins that bind and cut specific DNA sequences. They are often referred to as "molecular scissors" due to their ability to cleave DNA at precise locations. These enzymes are naturally found in bacteria and archaea, where they serve as a defense mechanism against invading viruses by degrading foreign DNA.

The specificity of a restriction enzyme is determined by the particular DNA sequence it recognizes, known as a restriction site. These sites are typically short, palindromic sequences, meaning they read the same forwards and backward on opposite DNA strands. When a restriction enzyme encounters its corresponding restriction site, it cleaves the DNA molecule.

The cleavage can result in two types of ends: sticky ends or blunt ends. Sticky ends are short, single-stranded overhangs that can anneal to complementary sticky ends from another DNA fragment. Blunt ends, on the other hand, are created when the enzyme cuts both strands directly opposite each other, leaving no overhangs.

Restriction enzymes are fundamental tools in molecular biology and biotechnology. They are widely used in genetic engineering, DNA cloning, and DNA sequencing. By cutting DNA at specific points, scientists can isolate genes, insert new genetic material into vectors, and analyze DNA fragments. This ability to precisely manipulate DNA has revolutionized research in genetics, medicine, and agriculture.