Biology 1.1

a harmful organism that invades the body and causes disease

Microorganisms are living things that are too small for us to see without a microscope. They include Bacteria and Viruses. 

You can fit 1000 bacteria into a millimetre marking on a rules, and 1,000,000 viruses! 

Bacteria can repoduce rapidly inside the body. They produce waste substances called toxins. This is why you feel poorly! 

Viruses reporiduce inside body cells. When lots of viruses are produced, they burst out of the cells! Next time you have a sore throat, imagine the viruses bursting out of the cells in the linign of oyur throat. 

He was a hungarian doctor. He noticed the doctors rarely washed their hands and often wore dirty clothes. Many patients often died of infection so Semmelweiss made the doctors weeash their hands with chlorine water before and after examination to stop germs going in and out. Soon after the death through infection rate lowered. 

Viruses are not living and are a lot smaller than bacteria. They cannot be killed by antibiotics either, the person has to be immune from the virus, this is due to vaccination, or the body produces antibodies to kill the virus. 

Do not use 'germ' for a microorganism that causes disease. The correct word is pathogen. 

White blood cells are like defense forces. They attack and destroy pathogens that have found their way inside the body.  

White blood cells are part of your immune system. Some white blood cells surround bacteria and ingest them. They take bacteria into their cytoplasm and kill them. 

Other white blood cells make chemicals called antibodies, which destroy the bacteria. or they may make antitoxins, which counteract the toxins that they bacteria are making. 

Lymphocytes, they attack pathogens in a different way to other white blood cells. 

The antibodies group round and stick to the pathogen. Sometimes they kill it directly and others they stick the pathogens together into clumps so it can be destroyed easily. 

Lymphocytes are cells.

Antibodies are molecules. 

Types of antibiotics are :- Penicillin and streptomycin. 

Not all antibiotics work against all the types of bacteria. 

If you get infected with chicken pox, the antibodies get rid of it. If chicken box comes back again, your body has a record of the antibody needed to kill the virus, so it can kill it before it does too much damage. 

An other type of immunization is vaccinating someone with some dead or inactive viruses or bacteria.