why are viruses not considered to be cells?

Answer 1

They don't have a cell membrane or cell wall, they don't have organelles, or any of the typical cell machinery. They are merely a nucleic acid encapsulated by a protein and a mechanism for injecting themselves into a cell. They rely another organisms cells for their replication.

Answer 2

Viruses are not considered to be cells because they are not living. Their only function is to multiply and to multiply, they destroy cells. A protein case surrounds some DNA and this DNA is injected into a cell. They can't breath or eat or feel pain and many scientists don't consider their multiplying to be sexual reproduction.

Answer 3

Viruses are generally just a few of DNA strands. They defy any standard definition of life because they don't really "live" on there own. They require all of the content of actual living cells to multiply and propagate.

Cells are much more complex and have all of the qualities that allow them to be defined as "alive"

Answer 4

Generally because they lack a cell wall and cytoplasm. They're usually simply a bundle of viral DNA/RNA, a protein shell and a few "hooks" to snag their defined prey. There's usually a method of injecting DNA/RNA into the host cell but besides that most are pretty basic.

Answer 5

The don't have cell membranes, they don't have independent organelles, they don't have cytoplasm...they're really just a tight package of DNA surrounded by a hard protein shell. They are entirely reliant on actual cells for reproduction (and the energy production requirements associated with reproduction).

Answer 6

They have no cell membrane or nucleus. They have floating DNA. See notes from web sites on KS4 B iology Bitesize

Answer 7

The simplest reason would be that they are not self sustained i.e they need a living cell to reproduce or use their DNA in any other way.

Answer 8

They have a very different structure than cells do and do not metabolize like cells. Believe me, they really are quite different things.