Viruses

• Viruses are not cells and are not living, but are considered organisms due to their ability to reproduce and cause disease.
• Viruses are about 10,000 times smaller than animal cells and cannot reproduce by themselves, but can use the machinery of another organism's cells to reproduce.
• Viruses cause damage to our bodies when they colonize and burst our cells, which is why they make us feel ill.
• Measles virus is spread by droplets when an infected person coughs or sneezes, causing a red rash across most of the body and fever.
• Human immunodeficiency virus (HIV) is spread through sexual contact, blood transfusion, or sharing needles, and causes a deficient or inadequate immune system.
• Tobacco mosaic virus (TMV) affects plants instead of humans, specifically tobacco and marigold plants, and discolors patches on the leaves, causing a mosaic pattern to form.
• The discolored patches on the leaves of plants infected with TMV prevent photosynthesis from taking place, causing the plant to produce insufficient sugars for proper growth.