Bacteria and Viruses p. 137 in ILL 6/1/12

Bacteria Characteristics Oldest forms of life on Earth Single- celled organisms Prokaryotic—no nucleus Contain DNA Most are consumers and eat other organisms for food, many are decomposers, some live in or on the body of other organisms, and some are producers

Bacteria Shape Most have rigid cell walls that give shape Bacteria come in one of 3 shapes rod (bacilli), sphere (cocci), or spiral (spirilla)

Bacteria Reproduction Bacteria can reproduce quickly by a process called binary fission. Their reproduction is slowed down by cold (refrigeration or freezing), heat (pasteurization and sterilization), and salting.

Bacteria Role in the World Good for the Environment Nitrogen cycle Decomposition Good for the People In food…cheese, yogurt, buttermilk, sour cream, etc. Medicines…fighting other bacteria, antibiotics, insulin Genetic Engineering…change genes of bacteria to make insecticides, cleansers, adhesives, etc

Bacteria Role in the World continued… Harmful Bacteria (infectious disease) Pathogenic (disease causing)…tuberculosis, Lyme disease, MRSA, leprosy, strep, etc. Can be treated with antibiotics--medicines taken by an infected person to kill the bacteria in the body (penicillin, amoxicillin, tetracycline) Some antibiotics have been overprescribed and by natural selection, bacteria have become resistant (can’t be killed) to certain medications. This is known as antibiotic resistance.

Bacteria

Bacteria Role in the World continued… Harmful Bacteria (Infectious disease) Can also be treated with vaccinations—substances that stimulate the body to produce chemicals (antibodies) that destroy familiar invaders

Viruses Characteristics/Reproduction Viruses are neither living nor dead They are non-cellular Viruses are significantly smaller than bacteria (5 billion virus particles can fit in a single drop of blood) Do not use energy, need food or create waste Contain DNA and protein coat Can only reproduce inside a host cell which it often destroys Can add their genetic material to a host cell that stays inactive for a very long time

Viruses Shapes Four main shapes: crystals, spheres, cylinders and spacecraft

Viruses Role in the World Good for the Environment Good for People Population control…limiting factor Good for People Can be manipulated to create medicines and treat some diseases (very new technology)

Viruses Role in the World continued… Harmful Viruses (infectious disease) Pathogenic (disease causing)…HIV, Hepatitis A, B, & C, Chicken Pox, Small Pox, Ebola, Rabies, Swine Flu, Influenza, Common Cold, etc. Cannot be cured with medications…only symptoms can be treated Many can be prevented with vaccinations (like bacterial infections)

Viruses