The characteristics of prokaryotic cells are:

• Membrane bound cell organelles such as Mitochondria, Golgi apparatus, Chloroplasts are absent.
• A membrane bound well defined nucleus is absent.
• Genetic material is circular DNA and occurs naked in the cell cytoplasm.
• The cell size ranges from 0.1 to 5.0 micrometre in size.

The major component of the bacterial cell wall is peptidoglycan or murein. This rigid structure of peptidoglycan, specific only to prokaryotes, gives the cell shape and surrounds the cytoplasmic membrane.

Overview of Bacterial Cell Walls A cell wall, not just of bacteria but for all organisms, is found outside of the cell membrane. It’s an additional layer that typically provides some strength that the cell membrane lacks, by having a semi-rigid structure.

Symptoms of viral diseases can include:

• Flu-like symptoms (fatigue, fever, sore throat, headache, cough, aches and pains)
• Gastrointestinal disturbances, such as diarrhea, nausea and vomiting.
• Irritability.
• Malaise (general ill feeling)
• Rash.
• Sneezing.
• Stuffy nose, nasal congestion, runny nose, or postnasal drip.

On a biological level, the main difference is that bacteria are free-living cells that can live inside or outside a body, while viruses are a non-living collection of molecules that need a host to survive.

| Ausmed. Bacteria and viruses are microbes (germs) which are very different to each other in structure and function. Despite the important structural and cultural differences, both bacteria and viruses can cause disease in similar ways: they invade and multiply within the host by evading the immune system.