Bacteria and Viruses Chapter 19

anthrax Strep throat

19-1 BACTERIA BACTERIA ARE CLASSIFIED AS PROKARYOTES – UNICELLULAR ORGANISMS THAT LACK A NUCLEUSBACTERIA ARE CLASSIFIED AS PROKARYOTES – UNICELLULAR ORGANISMS THAT LACK A NUCLEUS CLASSIFYING PROKARYOTESCLASSIFYING PROKARYOTES –EUBACTERIA – LARGER OF THE TWO KINGDOMS LIVE IN FRESH WATER, SALT WATER, LAND, AND ON AND IN HUMAN BODY.LIVE IN FRESH WATER, SALT WATER, LAND, AND ON AND IN HUMAN BODY.

Prokaryotes Traditionally all prokaryotes were classified as MoneransTraditionally all prokaryotes were classified as Monerans Also known as bacteria (p.) or bacterium (s.)Also known as bacteria (p.) or bacterium (s.) Presently, prokaryotes are divided into two kingdoms Archaebacteria & EubacteriaPresently, prokaryotes are divided into two kingdoms Archaebacteria & Eubacteria

1. K. Eubacteria Larger of the two kingdomsLarger of the two kingdoms Live almost everywhereLive almost everywhere Vital for life functions and industryVital for life functions and industry Both helpful and harmful (E. coli!)Both helpful and harmful (E. coli!)

2. K. Archaebacteria Believed to be earliest organisms to inhabit the EarthBelieved to be earliest organisms to inhabit the Earth All live in harsh environmentsAll live in harsh environments DIFFER FROM EUBACTERIA BY:DIFFER FROM EUBACTERIA BY: –NO PEPTIDOGLYCAN –DIFFERENT MEMBRANE LIPIDS –DNA more like eukaryotes’ DNA 3 separate phyla…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.Thrive at temperatures as great as 180ºF and pHs as low as 2. Natural springs.Natural springs. Yellowstone National ParkYellowstone 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:

IDENTIFYING PROKARYOTES IDENTIFIED BY SHAPE, CELL WALLS, MOVEMENT - FLAGELLA, WAY THEY GET ENERGYIDENTIFIED BY SHAPE, CELL WALLS, MOVEMENT - FLAGELLA, WAY THEY GET ENERGY –SHAPES: –BACILLI (RODS), COCCI (SPHERES), SPIRILLA (SPIRAL)

Classification according to shape. 1.Coccus (spherical)  Can be single cells, pairs, or chains  Example: Strep throat

2. Bacillus (rod) Single cellsSingle cells PairsPairs ChainsChains Example: anthraxExample: anthrax

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

Shapes:

4 Ways to Classify Bacteria 1. shape 2. Chemical nature of cell walls (Gram + or gram -) 3. How they move 4. How they obtain energy

Gram-positive bacteria Two kinds of cell walls in EubactieraTwo kinds of cell walls in Eubactiera Gram-positive bacteria have cell walls that are dyed a violet stain.Gram-positive bacteria have cell walls that are dyed a violet stain. Can be harmed by antibiotics like penicillinCan be harmed by antibiotics like penicillin example: streptococcusexample: streptococcus

Gram-negative bacteria More difficult to penetrate cell wall.More difficult to penetrate cell wall. Appear pink/red in Gram stainAppear pink/red in Gram stain Usually more difficult to treat with antibioticsUsually more difficult to treat with antibiotics Example: E-coliExample: E-coli

Movement Usually move through flagella or gliding along a surface.Usually move through flagella or gliding along a surface.

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 Feed off the remains of dead plants and animals. Seldom cause diseaseFeed off the remains of dead plants and animals. Seldom cause disease Parasites Live on or in other living organisms. Often cause disease

2 types of heterotrophic bacteria Chemoheterotrophs – take in organic molecules for energy and carbon (like humans!)Chemoheterotrophs – take in organic molecules for energy and carbon (like humans!) –Largest group of bacteria! Photoheterotrophs – use sunlight for energy, but also need to take in organic compoundsPhotoheterotrophs – use sunlight for energy, but also need to take in organic compounds

Autotrophic bacteria PhotoautotrophPhotoautotroph Use sunlight to convert carbon dioxide into energyUse sunlight to convert carbon dioxide into energy In lakes/streams/ oceansIn lakes/streams/ oceans Ex. cyanobacteriaEx. cyanobacteria Chemoautotroph Use inorganic chemical compounds to convert carbon dioxide into energy.

Releasing Energy 1. Obligate aerobes: require oxygen 2. Obligate anaerobes: cannot live in presence of oxygen 3. Facultative anaerobes: do not need oxygen, but can live in the presence of it (E. coli)

E.Growth and Reproduction 1. Binary fission: cell divides, asexual 2. Conjugation: transfer of genetic information from one cell to another, sexual 3. In unfavorable conditions, many bacteria can form endospores – can remain dormant for months or years (such as anthrax)

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 asexuallyAll reproduce asexually Usually through binary fissionUsually through binary fission Under certain conditions, bacteria can reproduce very quicklyUnder certain conditions, bacteria can reproduce very quickly –A small colony can double in 20 minutes. –animation animation

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.

Importance of Bacteria Without bacteria, we would die!Without bacteria, we would die! Bacteria produce energy, decompose dead matter into nutrients, convert nitrogen for plants, and produce vitamins in our intestinesBacteria produce energy, decompose dead matter into nutrients, convert nitrogen for plants, and produce vitamins in our intestines

Helpful bacteria Decompose food wastesDecompose food wastes Produce antibodiesProduce antibodies Genetic engineering – bacteria can produce heat-stable enzymes for medicinesGenetic engineering – bacteria can produce heat-stable enzymes for medicines Decomposition of dead plants and animalsDecomposition of dead plants and animals Industry & agriculture – cleaning oil spillsIndustry & agriculture – cleaning oil spills Break down sewage into water, carbon dioxide, nitrogenBreak down sewage into water, carbon dioxide, nitrogen

Bacteria on Plant roots Can be helpful in ‘fixing’ nitrogen for plant use. Rhizobium nodules on roots of soybeans convert nitrogen into ammonia

Controlling Bacteria 1. Sterilization: destroy bacteria by subjecting them to great heat or chemicals a. Boiling, frying, steaming can all kill bacteria b. Disinfectant chemical solutions can be used in homes and hospitals 2. Refrigeration – bacteria grow slowly at low temperatures

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.

Section 19.2 Viruses A.Viruses: particles of nucleic acid and protein 1. Nucleic acid = DNA or RNA that contains instructions for making new copies of the virus 2. Capsid: outer protein coat

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: A center core of DNA or RNA surrounded by a protein coat called a capsid.A center core of DNA or RNA surrounded by a protein coat called a capsid.

Viral Body Plans Genetic material is DNA or RNAGenetic material is DNA or RNA Coat is proteinCoat is protein Complex virus (bacteriophage) Polyhedral virusHelical virus

DNA and RNA Review DNA – deoxyribonucleic acid chemical compound (containing hydrogen, oxygen, nitrogen, carbon, and phosphorus) with instructions for coding proteins that determines your genetic makeup RNA – ribonucleic acid - nucleic acid that contains the sugar ribose

Viral Infections A virus binds to proteins on a cell and enters the cell 1. Infect cells and replicate inside host cell1. Infect cells and replicate inside host cell 2. Bacteriophage: viruses that infect bacteria2. Bacteriophage: viruses that infect bacteria

2 types of viral infections a. Lytic infection: virus enters cell, makes copies of itself and causes the cell to burst b. Lysogenic infection: virus embeds its DNA into DNA of host and is replicated with host cell’s DNA

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

The Prophage Prophage = viral DNA that is inserted into a cellProphage = viral DNA that is inserted into a cell The prophage can have the cell make copies of the virus right away or may wait several generations (a latent infection) and then begins making copies at a later timeThe prophage can have the cell make copies of the virus right away or may wait several generations (a latent infection) and then begins making copies at a later time

Viruses and Disease 1. Many viruses can be prevented through the use of vaccines (polio, measles, influenza) 2. Oncogenic viruses cause cancer 3. Retroviruses contain RNA 4. Prions contain no DNA or RNA, only protein

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.

Bacteria and Disease 1. Pathogen: disease-causing agents 2. 2 ways bacteria cause disease a. Break down tissues for food b. Release toxins to interfere with normal cellular activity 3. Many can be prevented with vaccines, can be treated with antibiotics

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

Controlling bacterial disease. ANTIBIOTICS – compounds that block the growth and reproduction of bacteriaANTIBIOTICS – compounds that block the growth and reproduction of bacteria Discovery of penicillin by Sir Alexander Fleming1928. Discovery of penicillin by Sir Alexander Fleming

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

Controlling Bacterial Growth Sterilization by heat – most bacteria are killed by high heat!Sterilization by heat – most bacteria are killed by high heat! Disinfectants – chemical solutions that kill pathogenic bacteriaDisinfectants – chemical solutions that kill pathogenic bacteria Food storage – boiling/frying/steaming kills, bacteria take longer to multiply in fridge (cooler temperatures)Food storage – boiling/frying/steaming kills, bacteria take longer to multiply in fridge (cooler temperatures)

How do we prevent viral diseases? Cannot be treated with ordinary antibioticsCannot be treated with ordinary antibiotics Prevention is best way to protect against viral diseases:Prevention is best way to protect against viral diseases: A vaccine is a weakened form of a virus that is used to stimulate the immune system to produce antiviral substances.A vaccine is a weakened form of a virus that is used to stimulate the immune system to produce antiviral substances.

Edward Jenner ( ) British physicianBritish physician Developed the first vaccine in 1798 for the viral disease smallpox.Developed the first vaccine in 1798 for the viral disease smallpox. Considered the “Father of Immunology”Considered the “Father of Immunology”

Common viral diseases: AIDSAIDS MeaslesMeasles ChickenpoxChickenpox SmallpoxSmallpox InfluenzaInfluenza The common coldThe common cold West NileWest Nile PolioPolio

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: In 1967 the World Health Organization launched a global effort to eradicate smallpox.In 1967 the World Health Organization launched a global effort to eradicate smallpox : Last known case of smallpox.1978 : Last known case of smallpox : W.H.O. declares the world free of smallpox.1980 : W.H.O. declares the world free of smallpox. Is there any smallpox virus left?Is there any smallpox virus left?

Smallpox upmc-biosecurity.org

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