Bacteria and Viruses Chapter 19

Taxonomy The branch of biology dealing with the classification of life. 1700s 2 kingdoms: plant and animal 1800s 3 kingdoms: plant, animal, and protista s 5 kingdoms: plant, animal, protista, fungi, monera Present: 6 kingdoms: eubacteria, archaebacteria, protista, animal, plant, fungi

Prokaryotes TraditionallyTraditionally all prokaryotes were classified as Monerans Monerans Gr. 1. Single or one AlsoAlso known as bacteria (p.) or bacterium (s.) Presently,Presently, the prokaryotes are divided into two kingdoms.

1. K. Eubacteria LargerLarger of the two kingdoms LiveLive almost everywhere VitalVital for life functions and industry BothBoth helpful and harmful

2. K. Archaebacteria Comes from the Greek word archaio which means “ancient” Believed by many to be the earliest organisms to inhabit the earth All live in harsh environments 3 separate phyla:

1. Methane-producing bacteria (methanogens) Intestinal tracts of animalsIntestinal tracts of animals Bottoms of swampsBottoms of swamps Used for sewage treatmentUsed for sewage treatment

2. Salt-loving bacteria (Halophiles) Thrive in high salinity waters where no other life can exist. Great Salt Lake Dead Sea

3. Hot-acidic loving (thermoacidophiles) Thrive at temperatures as great as 180ºF and pHs as low as 2. Natural springs. Yellowstone National Park

Facts about bacteria: Found everywhere Very small. Much smaller than any cell in our body. No membrane-bound structures or nucleus. (prokaryotes) Usually surrounded by a cell wall and a capsule for additional protection.

General structure:

Classification according to shape. 1.Coccus (spherical)  Can be single cells  Pairs  Chains  example  Strep throat

2. Bacillus (rod) Single cellsSingle cells PairsPairs ChainsChains exampleexample –anthrax

3. Spirillum(spiral)  Only exist as single cells Example: cholera, syphillis

Shapes:

Gram-positive bacteria ChemicalChemical nature of cell wall allows these bacteria to retain the violet stain. CanCan be harmed by antibiotics like penicillin example:example: streptococcus

Gram-negative bacteria MoreMore difficult to penetrate cell wall. UsuallyUsually more difficult to treat with antibiotics Example:Example: E-coli

Movement Usually move through flagella or gliding along a surface.Usually move through flagella or gliding along a surface. Surface StructuresSurface StructuresSurface StructuresSurface Structures

Metabolic Needs AerobicAerobic The most common typeThe most common type Cannot live without oxygenCannot live without oxygen Anaerobic Cannot live in the presence of oxygen Gets energy through fermentation (CO 2 )

Heterotrophic bacteria SaprobesSaprobes FeedFeed off the remains of dead plants and animals. Seldom cause disease Parasites Live on or in other living organisms. Often cause disease

Autotrophic bacteria PhotoautotrophPhotoautotroph UseUse sunlight to convert carbon dioxide into energy Ex.Ex. cyanobacteria Chemoautotroph Use inorganic chemical compounds to convert carbon dioxide into energy.

Genetic material Nucleoid= a single circular chromosome containing the DNA and RNA. Endospore = tough protective coat that covers and protects the nuclear material.

Reproduction All reproduce asexually Usually through binary fission Under certain conditions, bacteria can reproduce very quickly –A–A–A–A small colony can double in 20 minutes. –a–a–a–a nnnn iiii mmmm aaaa tttt iiii oooo nnnn

Binary fission The most common type of asexual reproduction. A single cell splits to form two daughter cells

Exchange of DNA Conjugation = genes move from one cell to another

Endospores A thick covering around the DNA that allows the bacterium to remain dormant for long periods of time. If necessary, many years.

Helpful bacteria DecomposeDecompose food wastes ProduceProduce vitamins antibodies GeneticGenetic engineering DecompositionDecomposition of dead plants and animals IndustryIndustry & agriculture

Plant roots Found on the roots of plants. Can be helpful in ‘fixing’ nitrogen for plant use. Rhizobium nodules on roots of soybeans

Are they living or non-living?Are they living or non-living? Contain genetic materialContain genetic material Lack organellesLack organelles Cannot reproduce unless inside a host cell. The word virus comes from the Greek word for POISONThe word virus comes from the Greek word for POISON Cause many diseases.Cause many diseases.

How big is a virus? Much smaller than bacterial cells.Much smaller than bacterial cells. Scientists have only recently, last 60 years, learned anything about virusesScientists have only recently, last 60 years, learned anything about viruses Classified according to the types of cells they attack.Classified according to the types of cells they attack.

Virus structure: Acenter core of DNA or RNA surrounded by a protein coat called a capsid.

2 main types of viral reproduction: LYTIC CYCLELYTIC CYCLE 1.Injects its nucleic acid (DNA or RNA) into the cell to take over cellular activities. LYSOGENIC CYCLE 1.Coexists with the cell without destroying the host cell

Lytic cycle

Lysogenic cycle

Direct the production of proteins by the host cell.Direct the production of proteins by the host cell. RETROVIRUS = A special type of virus that can make DNA which will produce new RNA, which, in turn, makes proteins that produce new viruses.RETROVIRUS = A special type of virus that can make DNA which will produce new RNA, which, in turn, makes proteins that produce new viruses. Ex.Ex.

Diseases caused by microorganisms: Pathogens: disease-causing agentsPathogens: disease-causing agents BACTERIAL DISEASE:BACTERIAL DISEASE: 1)Damage cells and tissues directly 2)Release toxins to interfere with normal cellular activity

Common bacterial diseases: Lyme diseaseLyme disease TetanusTetanus Strep throatStrep throat TuberculosisTuberculosis E. coli poisoningE. coli poisoning

Controlling bacterial disease. ANTIBIOTICSANTIBIOTICS Discovery of penicillin by Sir Alexander Flemming CameCame from a mold.

Common methods of bacterial infection. Food & water (E. coli)Food & water (E. coli) Coughing & sneezingCoughing & sneezing Sexually transmitted.Sexually transmitted. Carried by insectsCarried by insects

Food disease prevention Keep hands, and cooking utensils cleanKeep hands, and cooking utensils clean Canning and preservation techniques with food.Canning and preservation techniques with food. PasteurizationPasteurization FreezingFreezing

How do we prevent viral diseases? CannotCannot be treated with ordinary antibiotics Vaccinations.Vaccinations. The word comes from the vacca vacca Latin for “cow”. Avaccine is a weakened form of a virus that is used to stimulate the immune system to produce antiviral substances.

Edward Jenner ( ) BritishBritish physician DevelopedDeveloped the first vaccine in 1798 for the viral disease smallpox. ConsideredConsidered the “Father of Immunology”

Common viral diseases: AIDS Measles Chickenpox Smallpox Influenza The common cold West Nile Polio

Viral disease that is believed to have originated in Egypt at least 2000 years ago.Viral disease that is believed to have originated in Egypt at least 2000 years ago. Characterized by pox lesions and boils.Characterized by pox lesions and boils. Spread to the Americas by Spanish conquistadors.Spread to the Americas by Spanish conquistadors. Jenner’s vaccine was developed after observing a bovine disease: “cowpox”Jenner’s vaccine was developed after observing a bovine disease: “cowpox”

Eradication of smallpox: InIn 1967 the World Health Organization launched a global effort to eradicate smallpox : Last known case of smallpox : W.H.O. declares the world free of smallpox. IsIs there any smallpox virus left?

Viroids and Prions ViroidViroid Small disease causing particle.Small disease causing particle. Affect plantsAffect plants Prion Small disease causing particle. Affects animals. example :

Assignment: Pages 493Pages ,11,12,13,19,22,23,241-10,11,12,13,19,22,23,24 Page 495Page