Viruses and Prokaryotes

What is a Virus?A virus is a noncellular particle made up of genetic material and protein that can invade living cellsStructureCore of nucleic acid surrounded by a protein coat called a capsidCapsid can be DNA or RNA, but not bothCore can be several to several hundred genes

SO HOW BIG ARE VIRUSES???Viruses are REALLY small. They are much smaller than bacteria. They can only be seen with an electron microscope.

BacteriophageBacteriophages are viruses that infect bacteriaBacteriophageHead capsid and DNATail with fibers to attach to bacteria

T groupMost commonly studied are T group T1, T2, T3, T4 etc...T4 has a DNA core within a protein coat, and tail with tail fibers to attach to bacteria.

Viral shapesVariety of shapesRodTadpoleMany sided, helical or cubelike

VIRUS SHAPESRoundRod-shapedMany sided (icosohedral)

SHAPES MAY DIFFER BUTAll viruses have 1. Chromosome-like part that carries hereditary information The Core2. Protein coat: Protects hereditary information and provides the shape! The CapsidT4 BacteriophageTobacco MosaicVirusInfluenza Virus

ROUND VIRUSESHerpes virusThere are two types:Genitaloral

ROD-SHAPEDTobacco mosaic virus

MANY SIDEDbacteriophageE coli bacteria

Is this why viruses infect us?YES!Viruses need living organisms in order to reproduce and form more viruses! virusInjecting DNA

Virus SizeSize 20 to 400 nanometers (one nanometer is one billionth of a meter)Specificity usually infect specific organismsCannot infect animals if it infects plantsSome can infect wider varietyRabies all mammals, some birds

VIRUSES ARE SPECIFIC IN THE CELLS THEY INFECTRabies: only nervous system cells of mammalsCommon cold: infects cells on airway passage to lungsTobacco mosaic virus: only tobacco plantsnot wheat or corn

Lytic InfectionCause cells to lyse or burst

Infection chance contact virus with right kind of bacterium. Virus attaches to bacterium and injects its DNA. Most times, complete virus particle does not enter.Growth Bacterium cant tell difference between bacterial and viral DNA. RNA polymerase causes mRNA to be made from cell for virus. Viral DNA takes over and produces more DNA and viral proteins.Replication Virus uses bacterial material to make thousands of copies of the protein coat and DNA. Cell becomes filled with virus particles. (All three stages can happen with E. coli within 25 minutes!)DNA serves as central point for virus particles to be assembled. Cells fill with virus and lyse (burst). New viruses can now infect new cells.

SO HOW DO VIRUSES CAUSE DISEASE?Bacteriophage enzyme lyses thebacteriums cell wall, releasingnew bacteriophage particles thatcan attack other cells.Bacteriophage proteins and nucleic acids assemble into complete bacteriophage particlesBacteriophage takes over bacteriums metabolism, causing synthesis of new bacteriophage proteins and nucleic acidsBacteriophage injects DNA into bacteriumBacteriophage attaches to bacteriums cell wallBacteriophageBacteriophage DNABacteriophage proteinBacteriophage protein coatBacteriophage DNABacterialchromosomeLytic CycleSection 19-3

RetrovirusesRNA virusesWhen they infect a cell, they produce DNA copies of their RNA genes.Retroviruses have their genetic information copied backwards. RNA DNAOne retrovirus is HIV. Others cause cancer in animals and humans.The theory is that viruses were not the first living things. They are dependent on living things to survive.

EUBACTERIA AND ARCHAEBACTERIA:The two bacterial kingdomsBacteria on a pin head

EubacteriaTrue bacterialargest Kindgom of prokaryotesgenerally surrounded by cell wall composed of complex carbohydrateshave a cell membrane (some have 2 cell membranes)Some have flagella for movementFound everywhereSome produce diseaseSome photosyntheticsome very useful cheese is just one example

PROKARYOTIC CELLSProkaryote what does that mean? Classification of ProkaryotesAll prokaryotes were in kingdom Monera.Now 2 kingdomsEubacteria and archaebacteria

ArchaebacteriaArchaebacteria includes organisms that live in very harsh environmentsMethanogens live in oxygen free environments mud, digestive tracts of animalsExtremely salty environmentsHot springs

Identifying BacteriaCell ShapeRod bacilliSphere cocciSpiral spirilla

Bacterial ShapesRoundRodSpiral

Arrangement 2 cocci diplococcilong chains streptococciclumps, clusters staphylococci

Cell WallChemical nature Gram stainingHans Christian Gram2 dyes crystal violet (purple) and safranine (red)bacteria either take one or the otherIf only one thick layer of carbohydrate and protein molecules outside the cell membrane picked up crystal violet appeared purple GRAM POSITIVEIf cell had 2nd, outer layer of lipid and carbohydrate picked up safranine appeared red GRAM NEGATIVE

Bacterial movementpropelled by flagellalash, snake, or spiral forwardno movement

Bacterial RespirationObligate aerobes require oxygenObligate anaerobes must live in absence of oxygenexample is Clostridium botulinum Facultative anaerobes can live with or without oxygen

ReproductionSome can reproduce every 20 minutesHeld in check by food and production of wastes Types:Binary Fission Replication of DNA and division in halfAsexualConjugationSexual involves the exchange of genetic materialLong bridge of protein forms between the cellsDonor genetic information transferred to recipient through bridgeRecipient cell has different genes at the end than it did to begin with

Importance of BacteriaUsed in production of products we use every dayYogurtCheeseButtermilkSour creamPicklesSauerkrautVinegarWineIndustrydigest petroleumremove wastes and poisons from watersynthesizing drugs through genetic engineering

Symbiotic Relationships (mutuallism)E. coli in humans help us digest food make vitamins we cant, we give them a home, food, and transportationBacteria in the intestines of cattle allow them to break down cellulose (in grass and hay)

Bacteria in the EnvironmentBacteria are like the stage hands that allow the show to go on without being seen (or always given the credit)Bacteria recycle and decompose dead materialSaprophytes organisms that use the complex molecules of a once living organism as their food source

Sewage decompositionSewage treatment bacteria is added directly to the raw sewageHow does a septic tank work?

Nitrogen FixationAll organisms are TOTALLY dependent on monerans for NitrogenAll Plants need nitrogen to make amino acids (-NH2)Because animals eat plants, they get their proteins from plantsWhat percentage of the air is Nitrogen? Plants, and most other organisms cannot use this directlyNeed Nitrogen to be FIXED chemically as ammonia

Nitrogen FixationScientists can make synthetic nitrogen containing fertilizers by mixing Nitrogen and Hydrogen gases, heating to 500 degrees C and compressing it to 300 X normal atmospheric pressure dangerous, expensive, time consumingMany cyanobacteria can take nitrogen from the air and convert it to a useable form this is called Nitrogen FixationBacteria are the only organisms that can do this.Some plants have a symbiotic relationship with nitrogen fixing bacteriasoybean Rhizobium grows in nodules around roots

Diseases caused by Viruses and Moneransonly a small number of viruses and bacteria can cause disease Pathogens organisms that cause diseaseAll viruses infect living cellsDisease occurs when infection causes damage to the cells

Viruses and DiseaseExamples are:Small Pox PolioMeaslesAIDSMumpsInfluenzaYellow FeverRabiesCommon ColdEbola etc

VaccineThe bodys own defenses must be usedVaccine dead or weakened viruses that stimulate the bodies defense systemSymptoms can be treated sometimes, but once someone is infected by a virus, there is not much science can do

Bacteria and DiseaseBacterial diseases include:DiptheriaTBTyphoidTetnusHansen diseasesyphilischolerabubonic plagueFlesh Eating Bacteria

2 ways bacteria cause diseaseDamage cells and tissues of infected organisms directly by breaking down cellsReleasing toxins (poisons)Many bacteria can live without a host organism (on a petri dish)Rickettsiae cannot live outside a host cell. They have leaky cell wallsRickettsiae cause Rocky Mountain Spotted Fever, typhus, and Legionnaires disease

Measures to fight bacterial infection include:Antibiotics drugs and natural compounds that attack and destroy bacteria in the bodyNOT Effective against viruses