Viruses

• A VIRUS is a microscopic particle that gets inside a cell and often destroys the cell.

Red blood cell 7500 nm

Viruses are tiny, they are smaller than the smallest bacteria.

• Like living things, viruses contain proteins and nucleic acids, but viruses do not act like living things. • Viruses do not grow, break down food, use oxygen, respond to stimuli, etc. • Viruses cannot function on their own.

A virus CAN REPRODUCE inside a cell that serves as a HOST. HOST A HOST is a living thing that a virus or parasite lives on or in.

You need to remember that cells can produce all their structures, so in certain way they are like tiny factories.

So viruses force the host´s cells to make viruses instead of healthy new cells.

- Viruses

1 chain formed by nucleotides

2 chains formed by nucleotides

1 helix

2 helix

avian influenza RNA virus

Tobacco mosaic virus (RNA virus)

Hepatitis B virus (DNA virus)

Polio virus; RNA virus.

HIV Virus (RNA virus)

HIV infection

HIV infection

Variola virus, the cause of smallpox (DNA virus)

Influenza A virus (RNA virus)

T4 bacteriophage (DNA virus).

Bacteriophage (DNA virus)