Here's why:
* Viruses are obligate intracellular parasites: This means they rely entirely on the host cell's machinery and resources to replicate. They lack the necessary components (like ribosomes) to produce their own proteins and cannot create their own energy.
* They need a host cell's machinery: Viruses inject their genetic material (DNA or RNA) into a host cell. They then hijack the host cell's ribosomes, enzymes, and other cellular machinery to create copies of themselves.
* They use the host's resources: Viruses also steal the host cell's building blocks (like amino acids, nucleotides) to build new viral proteins and nucleic acids.
In essence, viruses are like molecular pirates: they commandeer a host cell and force it to produce more viruses until the host cell is destroyed.
