Post on 04-Jan-2016
Viruses and BacteriaViruses and Bacteria
Chapter 18Chapter 18
What is a virus?What is a virus?
Considered non-living particles by Considered non-living particles by most biologists because they:most biologists because they:– Do not carry out cellular respirationDo not carry out cellular respiration– Do not grow and developDo not grow and develop– Cannot replicate on their ownCannot replicate on their own
Viruses are named after:Viruses are named after:– The disease they cause (poliovirus)The disease they cause (poliovirus)– The organ they infect (adenovirus)The organ they infect (adenovirus)
Viral StructureViral Structure Genetic Material in Genetic Material in
the form of:the form of:– DNADNA– RNARNA
Capsid: outer Capsid: outer protein coatprotein coat– 4 common shapes4 common shapes
PolyhedralPolyhedral HelicalHelical EnvelopedEnveloped Bacteriophage or Bacteriophage or
phagephage
Polyhedral VirusesPolyhedral Viruses
Herpes virusHerpes virus AdenovirusAdenovirus Polio virusPolio virus
Helical VirusesHelical Viruses
Tobacco Tobacco Mosaic VirusMosaic Virus
Enveloped VirusesEnveloped Viruses
Contain an Contain an envelope made of envelope made of – LipidsLipids– CarbohydratesCarbohydrates– Proteins Proteins
ExamplesExamples– Influenza VirusInfluenza Virus– HIVHIV
BacteriophagesBacteriophages
““phage”phage” Is a virus that Is a virus that
attacks bacteriaattacks bacteria
Viruses are SpecificViruses are Specific
Each virus is Each virus is specialized specialized
Most viruses Most viruses are species-are species-specificspecific
Many viruses Many viruses are also cell-are also cell-specificspecific
Viral Replication CyclesViral Replication Cycles
Lytic CycleLytic Cycle– Kills the host cellKills the host cell
Lysogenic CycleLysogenic Cycle– Similar to lytic cycle but does not Similar to lytic cycle but does not
immediately kill host cellimmediately kill host cell– Viral genetic material recombines with Viral genetic material recombines with
host cell’s DNAhost cell’s DNA– Provirus: Viral DNA that is integrated Provirus: Viral DNA that is integrated
into host cell’s chromosomeinto host cell’s chromosome Examples: HSV I & II, hepatitis B, and Examples: HSV I & II, hepatitis B, and
chicken poxchicken pox
Lytic CycleLytic Cycle A virus attaches to a host cell. A virus attaches to a host cell. Virus releases its genetic material Virus releases its genetic material
into the host cell. into the host cell. The injected genetic material The injected genetic material
recruits the host cell's enzymes. recruits the host cell's enzymes. The enzymes make parts for more The enzymes make parts for more
new viruses. new viruses. The new parts assemble into new The new parts assemble into new
viruses. viruses. The new particles lyse (burst) the The new particles lyse (burst) the
host cell and exit. host cell and exit.
Lysogenic CycleLysogenic Cycle
RetrovirusesRetroviruses
Type of RNA Type of RNA virus that virus that reverse reverse transcribes transcribes itself into DNAitself into DNA
The newly The newly transcribed transcribed DNA inserts DNA inserts into host’s DNAinto host’s DNA
Ex: HIVEx: HIV
ProkaryotesProkaryotes
Unicellular Unicellular organisms without organisms without membrane-bound membrane-bound organellesorganelles
2 Kingdoms2 Kingdoms– ArchaebacteriaArchaebacteria– EubacteriaEubacteria
ArchaebacteriaArchaebacteria Live in harsh Live in harsh
environmentsenvironments 3 types3 types
– Methane-producersMethane-producers ““Methanogens”Methanogens” MarshesMarshes Lake sedimentsLake sediments Animal digestive tractsAnimal digestive tracts
– Salt-dwellersSalt-dwellers ““Halophiles”Halophiles” Dead SeaDead Sea
– Heat/Acid-dwellersHeat/Acid-dwellers ““Thermoacidophiles”Thermoacidophiles” Deep ocean ventsDeep ocean vents
Eubacteria: The Eubacteria: The HeterotrophsHeterotrophs Bacteria that obtain Bacteria that obtain
their nutrients from their nutrients from elsewhereelsewhere
Some are parasitesSome are parasites– Feed off of living Feed off of living
organismsorganisms Some are Some are
saprophytessaprophytes– Feed on dead Feed on dead
organisms organisms – Feed on organic Feed on organic
wastes (recyclers)wastes (recyclers)
Eubacteria: Photosynthetic Eubacteria: Photosynthetic AutotrophsAutotrophs
Bacteria that Bacteria that convert solar convert solar energy into foodenergy into food
Cyanobacteria or Cyanobacteria or blue-green algaeblue-green algae
Found in aquatic Found in aquatic environmentsenvironments
Composed of chains Composed of chains of independent cellsof independent cells
Eubacteria: Chemosythetic Eubacteria: Chemosythetic AutotrophsAutotrophs
Break down and Break down and release energy from release energy from inorganic compounds inorganic compounds such as Hsuch as H22SS
Important in Important in converting converting atmospheric nitrogen atmospheric nitrogen into usable forms into usable forms plants need plants need – Nitrogen FixationNitrogen Fixation
Structure Structure
Identifying Bacteria: Gram Identifying Bacteria: Gram StainStain
Gram staining Gram staining reflects differences reflects differences in cell wall in cell wall compositioncomposition– Gram-positive Gram-positive
bacteria stain bacteria stain blue/violetblue/violet
– Gram-negative Gram-negative bacteria stain pink bacteria stain pink
Identifying Bacteria: ShapesIdentifying Bacteria: Shapes
Bacterial ReproductionBacterial Reproduction
Asexually by binary Asexually by binary fissionfission
Very rapid at Very rapid at optimal conditions optimal conditions – can double every can double every
20 minutes20 minutes
Bacterial ReproductionBacterial Reproduction
Sexually by Sexually by conjugationconjugation
Common Bacterial DiseasesCommon Bacterial Diseases
DiseaseDisease AgentAgent SymptomsSymptoms TreatmentTreatmentStrep ThroatStrep Throat StreptococcuStreptococcu
s pyogeness pyogenessore throat, feversore throat, fever antibioticantibiotic
TetanusTetanus C. tetaniC. tetani stiff jaw, muscle stiff jaw, muscle spasm, paralysisspasm, paralysis
antibiotic, clean antibiotic, clean woundwound
TuberculosisTuberculosis M. M. tuberculosistuberculosis
chronic cough, chest chronic cough, chest pain,pain,
blood in sputum blood in sputum
antibioticantibiotic
Dental CariesDental Caries S. mutansS. mutans toothachetoothache remove decayremove decay
BotulismBotulism C. botulinumC. botulinum blurred vision, blurred vision, paralysis, slurred paralysis, slurred speachspeach
antitoxinsantitoxins
CholeraCholera Vibrio Vibrio choleracholera
diarrhea, vomitingdiarrhea, vomiting re-hydration, re-hydration, antibioticantibiotic
Traveler's Traveler's DiarrheaDiarrhea
Escherichia Escherichia colicoli
stomach cramps, stomach cramps, diarrheadiarrhea
re-hydration, re-hydration, antibioticantibiotic
Beneficial BacteriaBeneficial Bacteria Nitrogen FixationNitrogen Fixation
NN22 → → NONO22-- + NO + NO33
--
Converts Nitrogen into a usable Converts Nitrogen into a usable
form for plantsform for plants
FoodFood– Yogurt Yogurt – CheeseCheese– PicklesPickles– Sour creamSour cream– SauerkrautSauerkraut