Bacteria & Viruses Chapter 19

Bacteria Eubacteria live in harsh environments such as are classified into the kingdoms of live in harsh environments such as include a variety of lifestyles such as Bacteria Eubacteria Archaebacteria Infecting large organisms Thick mud Living in soil Animal digestive tracts Salty lakes Hot springs

Bacteria Microscopic life covers nearly every square centimeter of Earth! Bacteria are Prokaryotes (lack nucleus, small)

Until recently, all prokaryotes were placed in a single kingdom - Monera Now, prokaryotes are divided into two kingdoms: eubacteria and archeobacteria

1. Eubacteria: Common – live almost everywhere Very diverse Cell Wall containing peptidoglycan Aerobic

The Structure of Eubacteria Ribosome Cell membrane Cell wall Peptidoglycan Flagellum Pili DNA

2. Archaeobacteria No peptidoglycan Live in harsh, oxygen free environments Examples: thick mud, animal digestive tracts, hotsprings, salty lakes

Identifying Prokaryotes Shape: Rod – bacillus Spherical – coccus Spiral - spirilla

Bacteria Metabolism Heterotrophs – take in organic molecules example: Staphylocccus aureus

Autotrophs – Photosynthesizing: Example: fresh and salt water cyanobacteria

Growth and Reproduction 1. Binary Fission – DNA replication, cell divides in half. Asexual

Growth and Reproduction 2. Conjugation – Transfer of genetic information between 2 bacterial cells Sexual

Growth and Reproduction 3. Spore Formation – Bacteria form endopores when conditions are unfavorable Remain dormant until conditions improve, then germinate. This way bacteria can survive harsh conditions such as extreme heat, dryness, lack of nutrients

Importance of Bacteria 1. Decomposers – Return nutrients to the soil after being taken up by plants & animals Sewage treatment

Importance of Bacteria 2. Nitrogen fixers – Convert nitrogen in soil to a form plants can use to produce amino acids Fertilizers contain nitrogen

Importance of Bacteria 3. Human uses Cleaning up oil spills Removing waste products from water Genetic engineering Our intestines – E. coli Foods

Louis Pasteur Major contribution to medicine: 1. Created “Germ theory” – idea that bacteria cause some disease. 2. Creating hospital practices to minimize the spread of disease 3. Creating immunization using weakened forms of microbes 4. Determinined Rabies is transmitted by viruses. 5. Pasteurization - microbes in perishable food products are destroyed using heat.

Diseases Caused by Bacteria Bacteria cause disease in 2 ways: 1. Breaking down cells for food. 2. Releasing toxins that travel throughout the body.

Examples: Lyme disease, Tetanus, Tuberculosis, Diphtheria, Bacterial Meningitis, Strep throat, Tooth decay, Salmonella

Preventing Bacterial Disease Vaccine – weakened or killed pathogens injected into the body Body produces antibodies to prevent the disease in the future

Antibiotics – compounds that block the growth and reproduction of bacteria

Controlling Bacteria Sterilization – heat kills bacteria Disinfectants – chemical solutions that kill pathogenic bacteria Refrigeration – slows bacterial reproduction

Viruses A virus is not alive!!!! It can replicate only by infecting living cells. It’s made up of DNA or RNA surrounded by a protein coat. Head - Protein coat, (capsid) DNA Tail sheath Tail fiber

Viral Reproduction (Infection) Virus binds to surface of a cell and deposits DNA inside. Cell transcribes and translates viral DNA making copies of the virus Host cell is destroyed

Viruses vs. Living Cells

Examples of Viral Diseases Common cold, Influenza, Small pox, Warts, AIDS, Chickenpox, Measles, Hepatitis, West Nile, Polio