Students will begin to explore the differences between viruses, bacteria, and fungi The Diversity of Life

Today… Viruses The six kingdoms (Living Things) Prokaryotes –Archaebacteria –Eubacteria or Bacteria Eukaryotes –Animalia –Plantae –Protista –Fungi

VIRUSES Viruses are non-living particle. Technically they are not considered living organisms, since they cannot self replicate (they’re not a kingdom) Remember that living organisms: MRS GED 1.Made of cells 2.Able to self reproduce (sexually or asexually) 3.Respond to stimuli 4.Grow & develop 5.Take energy & use it 6.Stable chemical composition (DNA and other chemicals)

Virus structure Viruses: Just a protein coat for protection (capsid) and a nucleic acid (RNA or DNA) for information on how to make more copies of the same virus Cannot replicate/reproduce on its own! Needs a host…

Virus is a cellular parasite Uses cell machinery of a host cell to replicate and to produce more viruses They come in many varieties, sizes & shapes. Refer to Virus handout describing replication also known as the lytic cycle

Viruses cause diseases Viruses cause numerous diseases in Plants, animals, bacteria & fungi… Examples of human viruses: –Herpes virus –Hepatitis virus –Rabies –Influenza (“flu”) – respiratory infection (fever, headache, chills, cough, stuffy nose, sore throat) caused by a variety of viruses. Flu season: Nov. – March. * May be Passed on by sneezing, coughing – air, hand-to- mouth, etc. * Vaccine helps prevent outbreaks.

Plant Viruses Tobacco Mosaic Virus (TMV) causes mottling symptoms Rose mosaic virus Spots on fruit Wheat stunt virus

Living organisms PROKARYOTIC – Lack membrane-bound organelles; no nucleus present –Kingdom Archaebacteria and Eubacteria EUKARYOTIC – have membrane bound organelles with a nucleus. –Kingdoms Protista, Plantae, Fungi, Animalia

PROKARYOTES Bacteria are small and unicellular They have no internal organelles (no chloroplasts, nucleus, ER, mitochondria, etc.) Bacteria have a cell wall like plant cells. Bacteria have ribosomes.

Bacteria Replication is asexual – clonal, rapid simple division (no mitosis); reproduce by binary fission Pseudo-sexual reproduction, has means for Genetic exchange Called conjugation

Bacteria Bacterial forms: cocci (round), bacilli (rod), spirilli (spiral) Some forms are photosynthetic: cyanobacteria chloroplasts are present

Bacterial pathogens in Animals Typhoid, tuberculosis Bubonic plague or “Black Death”, transmitted by fleas (caused 25 million deaths in Medieval Europe) E. coli, Salmonella (food poisoning) 76 million illnesses worldwide

Bacterial control There are ways of controlling bacterial growth: Disinfectants Antibiotics Low temperatures High temperatures, Low oxygen

Beneficial Bacteria Decomposition in the biosphere – get rid of dead organisms, nature’s recyclers Intestinal Bacteria – supply vitamins (K) Commercial use: yogurt, sour cream, fermentation Genetically-engineered bacteria produce insulin and other important chemicals. Can also help clean up oil spills: oil ‘eating’ bacteria!

Eukaryotes Four Kingdoms: Fungi, Protista, Plantae, Animalia Have organelles (nucleus, mitochondria, etc.)

Kingdom Fungi Characteristics of fungi: Eukaryotic Non-photosynthetic, must obtain nutrients by absorption (produce digestive enzymes) Have a cell wall! Fungi cell wall is made of chitin and/or cellulose

Fungal morphology Most fungi come in thread-like strands, called hyphae (collectively called mycelium) Other fungi are single-celled, called yeasts. Form spores that can spread by wind, air or soil (give us allergies!) Fungi are so successful because they can reproduce both sexually and asexually –Sexual spores – (by meiosis) mushroom is spore-producing structure, formed by many hyphae –Asexual spores (by mitosis)

Fungi Hyphae: filaments

Significance of Fungi Many fungi are beneficial As decomposers: fungi obtain nutrition from organic matter, so they recycle nutrients

Fungi act as antibiotics Penicillin is produced by species of the fungus Penicillium, which kills bacteria. Discovered by Alexander Fleming in Left some unwashed plates with bacteria, went on vacation, and saw that a mold was growing, inhibiting the growth of the bacterial colony (Nobel Prize 1945).

Pathogenic fungi Pathogenic fungi grow within a host, using the host as food for replication Human Diseases: Athlete’s foot Yeast infections Ring worm Candidiasis

Pathogenic fungi: Mycotoxins Mycotoxins are harmful, toxic chemicals produced by fungi and which accumulate in infected food Aflatoxins contaminate corn and peanuts. The Aspergillus fungi grows on corn/peanuts and makes one of the most potent carcinogens known (aflatoxins)

Commercial uses of fungi Bread making – carbon dioxide bubbles help dough rise

Commercial uses of fungi Edible fungi are the sexual structures of fungi, the mycelium remains Mushrooms Morels Truffles

Other types of fungus Poisonous – some very dangerous intoxicants Hallucinogenic fungi