Viruses and Bacteria

Viruses Are not classified in any of the 5/6 kingdoms Are not considered living-they are not made up of cells Are made up of a piece of DNA or RNA inside a protein coat or capsid Can only reproduce inside a host cell May infect plants, animals, or even bacteria

Examples of diseases caused by viruses Herpes Polio The common cold Smallpox AIDS Chicken pox Measles Rabies Mononucleosis Influenza Some cancers

Structure of a virus

Other non-living particles causing disease Viroids –Single strands of RNA without a capsid that cause many agricultural crop diseases Prions –A single particle of protein capable of reproducing in some animal cells –Cause of Mad Cow disease, Creutzfeld- Jacob Disease, and Chronic wasting disease

Bacteria Are prokaryotic, they lack a ________and ____________ Are found everywhere! Are beneficial as well as harmful Are able to move by a flagellum or by secreting a slimy substance to slide on May be autotrophic _______________ or heterotrophic _____________________

Bacteria con’t May be aerobic ________________ or anaerobic _____________________ May reproduce asexually by binary fission (splitting in two) May reproduce sexually by conjugation (transferring a segment of DNA from one bacterium to another)

Structure of a Bacterium E. Coli with flagella Typical prokaryote structure

Bacteria come in 3 basic shapes Coccus (spherical) Bacillus (rod-shaped) Spirillum (spiral)

Two Kingdoms or One? All bacteria may belong to the kingdom Monera or… Kingdom Archaebacteria: –Live in intolerable habitats such as the Dead Sea, hot springs, sewage areas –Considered the first organisms on earth Kingdom Eubacteria –Heterotrophs: The decomposers The bacteria that cause disease such as: –Pneumonia, meningitis, strep throat, tetanus, diphtheria, botulism, tuberculosis –Autotrophs: Blue-Green bacteria Cyanobacteria

Why Bacteria are helpful… They are normal inhabitants of the human body and help to maintain homeostasis by aiding in digestion, providing certain needed vitamins, and secreting substances that ward off harmful organisms. The antibiotics streptomycin and erythromycin are synthesized from bacteria. They are decomposers; they recycle needed nutrients.

Helpful bacteria con’t Genetic engineering techniques are practiced on bacteria. Yogurt and cheese are produced by bacteria. Nitrogen fixers are planted to improve soils.

Bacteria that cause disease are called pathogens (so are all other disease causing organisms) The first bacteria proven to cause disease was Anthrax by the German physician Robert Koch

Antibiotics Antibiotics such as penicillin have been used to treat bacterial infections. Penicillin was discovered by Alexander Fleming in This wonder drug was synthesized from the bread mold Penicillium and saved thousands of lives. Alexander Fleming-”Chance favors the prepared mind”

Antibiotics today Effectiveness is threatened by the emergence of antibiotic resistance

Causes of antibiotic resistance Feeding healthy livestock antibiotics as a supplement Over-prescribing by doctors as a placebo Patients who fail to finish a prescribed antibiotic Antibiotic soaps and cleansers

Can you explain antibiotic resistance using the concept of evolution by natural selection?