Q.Define bacteriophage and write one example of it. OR Write two importance of biotechnology in medical field.

Bacteriophage (Structure and Examples)

We usually think of viruses as things that attack humans, animals or plants — but some viruses attack bacteria themselves. These are bacteriophages (literally "bacteria-eaters"). They played a starring role in proving that DNA is the genetic material, and today they are important tools in genetic engineering. Their neat, machine-like structure is well worth knowing.

The WHY — a virus that hunts bacteria

A bacteriophage is simply a virus whose host is a bacterium. Like all viruses it is an obligate parasite: it cannot reproduce on its own and must inject its genetic material into a bacterial cell, hijacking the cell's machinery to make more phages. Because bacteria are everywhere, phages are the most abundant biological entities on Earth.

Structure — the classic T-even phage

Many phages (like T4) have a distinctive "tadpole" / syringe-like shape:

To infect, the phage lands on a bacterium using its tail fibres, and injects its DNA through the tail — the protein coat stays outside. This was the basis of the famous Hershey–Chase experiment that confirmed DNA, not protein, is the genetic material.

Examples …