Bacteria and VirusesBacteria and Viruses

Chapter 19Chapter 19

anthrax

Strep throat

19-1 BACTERIA19-1 BACTERIA

• BACTERIA ARE CLASSIFIED AS BACTERIA ARE CLASSIFIED AS PROKARYOTES – PROKARYOTES – UNICELLULAR UNICELLULAR ORGANISMS THAT LACK A NUCLEUSORGANISMS THAT LACK A NUCLEUS

• CLASSIFYING PROKARYOTESCLASSIFYING PROKARYOTES– EUBACTERIA – EUBACTERIA – LARGER OF THE TWO LARGER OF THE TWO

KINGDOMSKINGDOMS• LIVE IN LIVE IN FRESH WATER, SALT WATER, LAND, FRESH WATER, SALT WATER, LAND,

AND ON AND IN HUMAN BODY.AND ON AND IN HUMAN BODY.

ProkaryotesProkaryotes

• Traditionally all prokaryotes were Traditionally all prokaryotes were classified as Moneransclassified as Monerans

• Also known as bacteria (p.) or Also known as bacteria (p.) or bacterium (s.)bacterium (s.)

• Presently, prokaryotes are divided Presently, prokaryotes are divided into two kingdoms Archaebacteria into two kingdoms Archaebacteria & Eubacteria& Eubacteria

1. K. Eubacteria1. K. Eubacteria

•Larger of the two kingdomsLarger of the two kingdoms•Live almost everywhereLive almost everywhere•Vital for life functions and Vital for life functions and

industryindustry•Both helpful and harmful (E. Both helpful and harmful (E.

coli!)coli!)

2. K. Archaebacteria2. K. Archaebacteria

• Believed to be earliest organisms Believed to be earliest organisms to inhabit the Earthto inhabit the Earth

• All live in harsh environmentsAll live in harsh environments• DIFFER FROM EUBACTERIA BY:DIFFER FROM EUBACTERIA BY:

– NO PEPTIDOGLYCANNO PEPTIDOGLYCAN– DIFFERENT DIFFERENT MEMBRANE LIPIDSMEMBRANE LIPIDS– DNA more like eukaryotes’ DNADNA more like eukaryotes’ DNA

• 3 separate phyla…3 separate phyla…

1. Methane-producing 1. Methane-producing bacteria (methanogens)bacteria (methanogens)

• Intestinal tracts Intestinal tracts of animalsof animals

• Bottoms of Bottoms of swampsswamps

• Used for Used for sewage sewage treatmenttreatment

2. Salt-loving bacteria 2. Salt-loving bacteria (Halophiles)(Halophiles)

• Thrive in high Thrive in high salinity waters salinity waters where no where no other life can other life can exist.exist.

• Great Salt Great Salt LakeLake

• Dead SeaDead Sea

3. Hot-acidic loving 3. Hot-acidic loving (thermoacidophiles)(thermoacidophiles)

• Thrive at Thrive at temperatures temperatures as great as as great as 180ºF and pHs 180ºF and pHs as low as 2.as low as 2.

• Natural springs.Natural springs.• Yellowstone Yellowstone

National ParkNational Park

Facts about bacteria:Facts about bacteria:

• Found everywhereFound everywhere• Very small. Much smaller than any Very small. Much smaller than any

cell in our body.cell in our body.• No membrane-bound structures or No membrane-bound structures or

nucleus. (prokaryotes)nucleus. (prokaryotes)• Usually surrounded by a cell wall Usually surrounded by a cell wall

and a capsule for additional and a capsule for additional protection.protection.

General structure:General structure:

IDENTIFYING PROKARYOTESIDENTIFYING PROKARYOTES

• IDENTIFIED BY IDENTIFIED BY SHAPE, CELL SHAPE, CELL WALLS, MOVEMENT - WALLS, MOVEMENT - FLAGELLA, WAY THEY GET FLAGELLA, WAY THEY GET ENERGYENERGY

– SHAPESSHAPES: : – BACILLI (BACILLI (RODS)RODS), ,

COCCI (COCCI (SPHERES)SPHERES), SPIRILLA , SPIRILLA (SPIRAL)(SPIRAL)

Classification according to Classification according to shape.shape.

1.1. Coccus (spherical)Coccus (spherical) Can be single cells, pairs, or Can be single cells, pairs, or

chainschains Example: Example: Strep throatStrep throat

2. 2. Bacillus (rod)Bacillus (rod)• Single cellsSingle cells• PairsPairs• ChainsChains

• Example: Example: anthraxanthrax

3. 3. Spirillum(spiral)Spirillum(spiral)

Only exist as single cellsOnly exist as single cells

Example:Example:cholera, syphilischolera, syphilis

Shapes:Shapes:

4 Ways to Classify 4 Ways to Classify BacteriaBacteria

1. shape1. shape

2. Chemical nature of cell walls 2. Chemical nature of cell walls

(Gram + or gram -)(Gram + or gram -)

3. How they move3. How they move

4. How they obtain energy4. How they obtain energy

Gram-positive bacteriaGram-positive bacteria

• Two kinds of cell walls in Two kinds of cell walls in EubactieraEubactiera

• Gram-positive bacteria have cell Gram-positive bacteria have cell walls that are dyed a violet stain.walls that are dyed a violet stain.

• Can be harmed by antibiotics like Can be harmed by antibiotics like penicillinpenicillin

• example: example: streptococcusstreptococcus

Gram-negative bacteriaGram-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 Usually more difficult to treat with

antibioticsantibiotics• Example: Example: E-coliE-coli

MovementMovement

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

Metabolic NeedsMetabolic Needs

• AerobicAerobic• The most The most

common typecommon type• Cannot live Cannot live

without without oxygenoxygen

• AnaerobicAnaerobic• Cannot live in Cannot live in

the presence of the presence of oxygenoxygen

• Gets energy Gets energy through through fermentation fermentation (CO(CO22))

Heterotrophic bacteriaHeterotrophic bacteria

• SaprobesSaprobes• Feed off the Feed off the

remains of remains of dead plants dead plants and animals. and animals. Seldom cause Seldom cause diseasedisease

• ParasitesParasites• Live on or in Live on or in

other living other living organisms. organisms. Often cause Often cause diseasedisease

2 types of heterotrophic 2 types of heterotrophic bacteriabacteria

• Chemoheterotrophs Chemoheterotrophs – take in organic – take in organic molecules for energy and carbon (like molecules for energy and carbon (like humans!)humans!)– Largest group of bacteria!Largest group of bacteria!

• PhotoheterotrophsPhotoheterotrophs – use sunlight for – use sunlight for energy, but also need to take in organic energy, but also need to take in organic compoundscompounds

Autotrophic bacteriaAutotrophic bacteria

• PhotoautotrophPhotoautotroph• Use sunlight to Use sunlight to

convert carbon convert carbon dioxide into energydioxide into energy

• In lakes/streams/ In lakes/streams/ oceansoceans

• Ex. cyanobacteriaEx. cyanobacteria

• ChemoautotropChemoautotrophh

• Use inorganic Use inorganic chemical chemical compounds to compounds to convert carbon convert carbon dioxide into dioxide into energy.energy.

Releasing EnergyReleasing Energy

1. Obligate aerobes: require 1. Obligate aerobes: require oxygenoxygen

2. Obligate anaerobes: cannot 2. Obligate anaerobes: cannot live in presence of oxygenlive in presence of oxygen

3. Facultative anaerobes: do not 3. Facultative anaerobes: do not need oxygen, but can live in the need oxygen, but can live in the presence of it (E. coli)presence of it (E. coli)

E.E. Growth and ReproductionGrowth and Reproduction1. Binary fission: cell divides, asexual1. Binary fission: cell divides, asexual2. Conjugation: transfer of genetic 2. Conjugation: transfer of genetic information from one cell to another, information from one cell to another, sexualsexual3. In unfavorable conditions, many 3. In unfavorable conditions, many bacteria can form endospores – can bacteria can form endospores – can remain dormant for months or years remain dormant for months or years (such as anthrax)(such as anthrax)

Genetic materialGenetic material

• Nucleoid= a Nucleoid= a single circular single circular chromosome chromosome containing the containing the DNA and RNA.DNA and RNA.

• Endospore = Endospore = tough protective tough protective coat that covers coat that covers and protects the and protects the nuclear material.nuclear material.

ReproductionReproduction

• All reproduce asexuallyAll reproduce asexually• Usually through binary fissionUsually through binary fission• Under certain conditions, bacteria Under certain conditions, bacteria

can reproduce very quicklycan reproduce very quickly– A small colony can double in 20 A small colony can double in 20

minutes.minutes.– animationanimation

Binary fissionBinary fission

• The most The most common type common type of asexual of asexual reproduction. reproduction.

• A single cell A single cell splits to form splits to form two daughter two daughter cellscells

Exchange of DNA Exchange of DNA

Conjugation Conjugation = genes = genes move from move from one cell to one cell to anotheranother

EndosporesEndospores

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

Importance of BacteriaImportance of Bacteria

• Without bacteria, we would die!Without bacteria, we would die!• Bacteria produce energy, Bacteria produce energy,

decompose dead matter into decompose dead matter into nutrients, convert nitrogen for nutrients, convert nitrogen for plants, and produce vitamins in our plants, and produce vitamins in our intestinesintestines

Helpful bacteriaHelpful bacteria

• Decompose food wastesDecompose food wastes• Produce antibodiesProduce antibodies• Genetic engineering – bacteria can Genetic engineering – bacteria can

produce heat-stable enzymes for produce heat-stable enzymes for medicinesmedicines

• 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 Break down sewage into water, carbon

dioxide, nitrogendioxide, nitrogen

Bacteria on Plant rootsBacteria on Plant roots

• Can be helpful in Can be helpful in ‘fixing’ nitrogen ‘fixing’ nitrogen for plant use.for plant use.

• Rhizobium Rhizobium nodules on roots nodules on roots of soybeans of soybeans convert nitrogen convert nitrogen into ammoniainto ammonia

Controlling BacteriaControlling Bacteria

1. Sterilization: destroy bacteria by 1. Sterilization: destroy bacteria by subjecting them to great heat or subjecting them to great heat or chemicals chemicals

a. Boiling, frying, steaming can all a. Boiling, frying, steaming can all kill bacteria kill bacteriab. Disinfectant chemical b. Disinfectant chemical solutions can be used in solutions can be used in

homes and hospitalshomes and hospitals2. Refrigeration – bacteria grow slowly 2. Refrigeration – bacteria grow slowly at low temperaturesat 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 Cannot reproduce unless inside a host cell.host cell.

• The word virus comes from the The word virus comes from the Greek word for POISONGreek word for POISON

• Cause many diseases.Cause many diseases.

Section 19.2 VirusesSection 19.2 Viruses

A.A. Viruses: particles of Viruses: particles of nucleic acid and proteinnucleic acid and protein

1. Nucleic acid = DNA or 1. Nucleic acid = DNA or RNA that contains RNA that contains instructions for making instructions for making new copies of the virusnew copies of the virus

2. Capsid: outer protein 2. Capsid: outer protein coatcoat

How big is a virus?How big is a virus?

• Much smaller than Much smaller than bacterial cells.bacterial cells.

• Scientists have Scientists have only recently, last only recently, last 60 years, learned 60 years, learned anything about anything about virusesviruses

• Classified Classified according to the according to the types of cells they types of cells they attack.attack.

Virus structure:Virus structure:

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

Viral Body Viral Body PlansPlans

• Genetic material Genetic material is DNA or RNAis DNA or RNA

• Coat is proteinCoat is protein

Complex virus (bacteriophage)Polyhedral virusHelical virus

DNA and RNA ReviewDNA and RNA Review

DNADNA – deoxyribonucleic acid – deoxyribonucleic acidchemical compound (containing chemical compound (containing

hydrogen, oxygen, nitrogen, carbon, and hydrogen, oxygen, nitrogen, carbon, and phosphorus) with instructions for coding phosphorus) with instructions for coding proteins that determines your genetic proteins that determines your genetic makeupmakeupRNA RNA – ribonucleic acid - nucleic acid – ribonucleic acid - nucleic acid that contains the sugar ribosethat contains the sugar ribose

Viral InfectionsViral Infections

A virus binds to proteins on a cell A virus binds to proteins on a cell and enters the celland enters the cell

• 1. Infect cells and replicate 1. Infect cells and replicate inside host cellinside host cell

• 2. Bacteriophage: viruses 2. Bacteriophage: viruses that infect bacteriathat infect bacteria

2 types of viral infections2 types of viral infections

a. Lytic infection:a. Lytic infection: virus enters virus enters cell, makes copies of itself and cell, makes copies of itself and causes the cell to burstcauses the cell to burst

b. Lysogenic infection:b. Lysogenic infection: virus virus embeds its DNA into DNA of host embeds its DNA into DNA of host and is replicated with host cell’s and is replicated with host cell’s DNADNA

2 main types of viral 2 main types of viral reproduction:reproduction:

• LYTIC CYCLELYTIC CYCLE

1.1. Injects its Injects its nucleic acid nucleic acid (DNA or RNA) (DNA or RNA) into the cell to into the cell to take over take over cellular cellular activities.activities.

• LYSOGENIC LYSOGENIC CYCLECYCLE

1.1. Coexists with Coexists with the cell the cell without without destroying destroying the host cellthe host cell

Lytic cycleLytic cycle

Lysogenic cycleLysogenic cycle

The ProphageThe Prophage

• Prophage = viral DNA that is inserted Prophage = viral DNA that is inserted into a cellinto a cell

• The prophage can have the cell The prophage can have the cell make copies of the virus right away make copies of the virus right away or may wait several generations (a or may wait several generations (a latent infection) and then begins latent infection) and then begins making copies at a later timemaking copies at a later time

Viruses and DiseaseViruses and Disease

1. Many viruses can be prevented 1. Many viruses can be prevented through the use of vaccines through the use of vaccines

(polio, measles, influenza)(polio, measles, influenza)

2. Oncogenic viruses cause cancer2. Oncogenic viruses cause cancer

3. Retroviruses contain RNA3. Retroviruses contain RNA

4. Prions contain no DNA or RNA, only 4. Prions contain no DNA or RNA, only proteinprotein

• Direct the production of proteins by Direct the production of proteins by the host cell.the host cell.

• RETROVIRUS = A special type of RETROVIRUS = A special type of virus that can make DNA which will virus that can make DNA which will produce new RNA, which, in turn, produce new RNA, which, in turn, makes proteins that produce new makes proteins that produce new viruses.viruses.

• Ex. Ex.

Bacteria and DiseaseBacteria and Disease1. Pathogen: disease-causing agents1. Pathogen: disease-causing agents2. 2 ways bacteria cause disease2. 2 ways bacteria cause disease

a. Break down tissues for fooda. Break down tissues for foodb. Release toxins to interfere b. Release toxins to interfere

with normal cellular activitywith normal cellular activity3. Many can be prevented with 3. Many can be prevented with

vaccines, can be treated with vaccines, can be treated with antibioticsantibiotics

Common bacterial Common bacterial diseases:diseases:

•Lyme diseaseLyme disease•TetanusTetanus•Strep throatStrep throat•TuberculosisTuberculosis•E. coli poisoningE. coli poisoning

Controlling bacterial Controlling bacterial disease.disease.

• ANTIBIOTICS – ANTIBIOTICS – compounds that compounds that block the growth block the growth and reproduction and reproduction of bacteriaof bacteria

• 1928. Discovery 1928. Discovery of penicillin by Sir of penicillin by Sir Alexander Alexander FlemingFleming

Common methods of Common methods of bacterial infection.bacterial infection.

• Food & water Food & water (E. coli)(E. coli)

• Coughing & Coughing & sneezingsneezing

• Sexually Sexually transmitted.transmitted.

• Carried by Carried by insectsinsects

Controlling Bacterial Controlling Bacterial GrowthGrowth

• Sterilization by heatSterilization by heat – most – most bacteria are killed by high heat!bacteria are killed by high heat!

• DisinfectantsDisinfectants – chemical solutions – chemical solutions that kill pathogenic bacteriathat kill pathogenic bacteria

• Food storageFood storage – – boiling/frying/steaming kills, boiling/frying/steaming kills, bacteria take longer to multiply in bacteria take longer to multiply in fridge (cooler temperatures)fridge (cooler temperatures)

How do we prevent viral How do we prevent viral diseases?diseases?

• Cannot be treated with ordinary Cannot be treated with ordinary antibioticsantibiotics

• Prevention is best way to protect against Prevention is best way to protect against viral diseases: viral diseases:

• A vaccine is a weakened form of a virus A vaccine is a weakened form of a virus that is used to stimulate the immune that is used to stimulate the immune system to produce antiviral substances.system to produce antiviral substances.

Edward Jenner (1749-Edward Jenner (1749-1823)1823)

• British physicianBritish physician• Developed the Developed the

first vaccine in first vaccine in 1798 for the 1798 for the viral disease viral disease smallpox.smallpox.

• Considered the Considered the “Father of “Father of Immunology”Immunology”

Common viral diseases:Common viral diseases:

• AIDSAIDS• MeaslesMeasles• ChickenpoxChickenpox• SmallpoxSmallpox• InfluenzaInfluenza• The common coldThe common cold• West NileWest Nile• PolioPolio

• Viral disease that is believed to have Viral disease that is believed to have originated in Egypt at least 2000 originated in Egypt at least 2000 years ago.years ago.

• Characterized by pox lesions and Characterized by pox lesions and boils.boils.

• Spread to the Americas by Spanish Spread to the Americas by Spanish conquistadors.conquistadors.

• Jenner’s vaccine was developed after Jenner’s vaccine was developed after observing a bovine disease: “cowpox”observing a bovine disease: “cowpox”

Eradication of smallpox:Eradication of smallpox:

• In 1967 the World Health In 1967 the World Health Organization launched a global Organization launched a global effort to eradicate smallpox.effort to eradicate smallpox.

• 1978 : Last known case of smallpox.1978 : Last known case of smallpox.• 1980 : W.H.O. declares the world 1980 : W.H.O. declares the world

free of smallpox.free of smallpox.• Is there any smallpox virus left?Is there any smallpox virus left?

SmallpoxSmallpox

upmc-biosecurity.org

Viroids and PrionsViroids and Prions

•ViroidViroid•Small Small

disease disease causing causing particle.particle.

•Affect plantsAffect plants

• PrionPrion• Small disease Small disease

causing causing particle.particle.

• Affects animals.Affects animals.• exampleexample::