Viruses: Living or Non Viruses: Living or Non Living?Living?

Phage = virusPhage = virus BacteriophagBacteriophag

e = virus with e = virus with bacteria hostbacteria host

Virus = Virus = genetic info genetic info with protein with protein shellshell

Viruses: Hershey – Chase Viruses: Hershey – Chase ExperimentExperiment

Viruses: Reproductive CycleViruses: Reproductive CycleLytic vs LysogenicLytic vs Lysogenic

Viruses: RetrovirusViruses: Retrovirus HIV: HIV: RetrovirusRetrovirus RNA instead of RNA instead of

DNADNA Enzyme Enzyme reverse reverse

transcriptasetranscriptase Once in host, Once in host,

converts RNA converts RNA into DNA into DNA (reverse (reverse transcription)transcription)

Viruses: RetrovirusViruses: Retrovirus Reverse TranscriptionReverse Transcription

Classification: DomainsClassification: Domains Major Division of Major Division of

Life: Prokaryotes Life: Prokaryotes vs. Eukaryotesvs. Eukaryotes

Domain: ArchaebacteriaDomain: Archaebacteria Archaea live in Archaea live in

EXTREME conditionsEXTREME conditions anaerobic swampsanaerobic swamps salt lakessalt lakes acidic hot springsacidic hot springs deep-sea deep-sea

hydrothermal ventshydrothermal vents animal digestive animal digestive

systems systems

Kingdom MONERA Kingdom MONERA (Bacteria)(Bacteria)

Prokaryotes - Prokaryotes - oldest life-formsoldest life-forms Remain most Remain most

numerous and numerous and widespread widespread organisms on organisms on Earth todayEarth today

Kingdom MONERAKingdom MONERA Prokaryotic: no Prokaryotic: no

nucleus, no nucleus, no organellesorganelles

Single-celled, Single-celled, Contains double-Contains double-stranded circular stranded circular chromosomal DNAchromosomal DNA

Cell wall: Cell wall: peptidoglycanpeptidoglycan

Kingdom MONERA: ShapesKingdom MONERA: Shapes Spheres (cocci): Spheres (cocci):

most commonmost common

Rods (bacilli)Rods (bacilli)

Curves or spirals Curves or spirals

Kingdom MONERAKingdom MONERA Cyanobacteria:Cyanobacteria:

AutotrophsAutotrophs Photoautotrophs and ChemoautotrophsPhotoautotrophs and Chemoautotrophs

Bacteria:Bacteria: heterotrophsheterotrophs

Kingdom MONERA: Kingdom MONERA: Genetic EngineeringGenetic Engineering

Bacteria can reproduce Bacteria can reproduce both asexually (both asexually (binary binary fissionfission) and sexually) and sexually

This discovery led to the This discovery led to the development of development of recombinant DNA recombinant DNA technologytechnology a set of techniques for combining a set of techniques for combining

genes from different sourcesgenes from different sources

Kingdom MONERA:Kingdom MONERA:Gene ExchangingGene Exchanging

Can occur in 3 waysCan occur in 3 ways TransformationTransformation: :

taking up of DNA taking up of DNA from the fluid from the fluid surrounding the cellsurrounding the cell

DNA enterscell

Fragment ofDNA from anotherbacterial cell

Bacterial chromosome(DNA)

Kingdom MONERA:Kingdom MONERA:Gene ExchangingGene Exchanging

Transduction:Transduction: transfer of transfer of bacterial genes by bacterial genes by phage (virus)phage (virus)

ConjugationConjugation: union : union of cells and the DNA of cells and the DNA transfer between transfer between themthem

Phage

Fragment ofDNA from anotherbacterial cell(former phagehost)

Kingdom MONERA: PlasmidsKingdom MONERA: Plasmids PlasmidPlasmid: a : a

small circular small circular DNA DNA molecule molecule separateseparate from the from the bacterial bacterial chromosomechromosome

Kingdom MONERA:Kingdom MONERA:Genetic EngineeringGenetic Engineering Restriction Restriction

enzymesenzymes cut DNA cut DNA at specific pointsat specific points

DNA ligaseDNA ligase “pastes” the DNA “pastes” the DNA fragments fragments togethertogether

The result is The result is recombinant DNArecombinant DNA

Kingdom MONERA:Kingdom MONERA:Recombinant DNARecombinant DNA