Pathogens – Bacteria & Pathogens – Bacteria & VirusesViruses

Protists & Fungi TooProtists & Fungi Too

A Pathogen is…A Pathogen is…

Pathogen = Any disease causing Pathogen = Any disease causing agent.agent.

–Examples:Examples: Bacteria: Streptococcus, StaphylococcusBacteria: Streptococcus, Staphylococcus Virus: HIV, Influenza (Swine Flu), The Virus: HIV, Influenza (Swine Flu), The

common coldcommon cold Protist: Plasmodium (malaria)Protist: Plasmodium (malaria) Fungi: Ringworm, Athletes FootFungi: Ringworm, Athletes Foot

Viruses – Properties of LifeViruses – Properties of Life

Properties of LifeProperties of LifeCellular organizationCellular organization

ReproductionReproduction YesYesMetabolismMetabolism

HomeostasisHomeostasis

AdaptionAdaption YesYesResponsivenessResponsiveness YesYesGrowth and DevelopmentGrowth and Development NO

NO

NO

NO

Virus SizeVirus Size

Viruses are SOOO Small!Viruses are SOOO Small!

Too small to see with a Too small to see with a regular light regular light microscopemicroscope

Must use an Must use an electronelectron microscope to be microscope to be seen.seen.

Parts of a VirusParts of a Virus CapsidCapsid= “head”…protein that encloses = “head”…protein that encloses

viral genomeviral genome GenomeGenome= double stranded DNA OR = double stranded DNA OR

single stranded DNA or RNAsingle stranded DNA or RNA

Viral Body PlansViral Body Plans

Genetic material is DNA or Genetic material is DNA or RNARNA

Coat is protein Coat is protein

Complex virus(bacteriophage)

Polyhedral virus

Rod-shaped virus

head

sheath

tail fiber

Viruses are Obligate Intracellular Viruses are Obligate Intracellular ParasitesParasites

Obligate like an Obligate like an obligationobligation – can only – can only replicate inside other cellsreplicate inside other cells

Must live within a Must live within a specificspecific host cell – host cell – exampleexample: cats don’t get chicken pox: cats don’t get chicken pox

Use the host cell for replication, metabolism, Use the host cell for replication, metabolism, etc.etc.

Viruses cause diseaseViruses cause disease

InfluenzaInfluenza– Infects the upper respiratory Infects the upper respiratory

tracttract

Can also cause cancerCan also cause cancer– Hepatitis B Hepatitis B liver cancer liver cancer– Epstein-Barr virus Epstein-Barr virus Burkitt’s Burkitt’s

lymphomalymphoma– Human Papilloma Virus Human Papilloma Virus

cervical cancercervical cancer

HIV, the AIDS virusHIV, the AIDS virus

Glycoproteins on HIV envelope Glycoproteins on HIV envelope recognize surface proteins of human recognize surface proteins of human white blood cellswhite blood cells

RNA virusRNA virus Includes the reverse transcriptase Includes the reverse transcriptase

enzymeenzyme

Defenses against virusesDefenses against viruses

Skin and mucus membranesSkin and mucus membranes Inflammation (redness, swelling, Inflammation (redness, swelling,

warmth and pain)warmth and pain) White blood cellsWhite blood cells Antibodies- specific proteins that Antibodies- specific proteins that

target a specific virustarget a specific virus Interferons- enzymes that prevent Interferons- enzymes that prevent

the virus from replicatingthe virus from replicating

T4 Bacteriophages on Escherichia coli) bacteria. T4 bacteriophages are parasites of E. coli, a bacteria common in the human gut. The virus attaches itself to the host bacteria cell wall by its tail fibers. The sheath then contracts, injecting the contents of the head (DNA) into the host. The viral DNA makes the bacteria manufacture more copies of the virus. TEM X40,000.

Credit: © Dr. George Chapman/Visuals Unlimited

T4 Bacteriophages on Escherichia coli bacteria. T4 bacteriophages are parasites of E. coli, a bacteria common in the human gut. The virus attaches itself to the host bacteria cell wall by its tail fibers. The sheath then contracts, injecting the contents of the head (DNA) into the host. The viral DNA makes the bacteria manufacture more copies of the virus. TEM X60,000.

Credit: © Dr. George Chapman/Visuals Unlimited

Bacteria - ProkaryotesBacteria - Prokaryotes

Eubacteria = True Bacteria. Eubacteria = True Bacteria. – Cell wall contains the carbohydrate Cell wall contains the carbohydrate

peptidoglycanpeptidoglycan

Archaeabacteria = Ancient Bacteria. Archaeabacteria = Ancient Bacteria. – NO peptidoglycan in cell walls. NO peptidoglycan in cell walls. – MORE similar to Eukaryotes!!! (US)MORE similar to Eukaryotes!!! (US)– Live in harsh environmentsLive in harsh environments

Bacteria are very small

This is a pore in human skin and the yellow spheres are bacteria

Bacteria are very small compar-ed to cells with nuclei

Bacteria compared to a white blood cell that is going to eat it

Bacteria

Clean skin has about 20 million bacteria per square inch

StructureStructure

No nucleusNo nucleus No membrane No membrane

bound organellesbound organelles DNA is circular DNA is circular

PlasmidsPlasmids

Bacteria ShapesBacteria ShapesPage 546

E. coli is a gram-negative, facultatively anaerobic, rod prokaryote undergoing conjugation. One strain has fimbriae. E. coli can cause urinary tract infections, traveler's diarrhea, nosocomial infections, and a variety of skin and wound infections such as scalded skin syndrome, scarlet fever, erysipelas and impetigo. TEM.

Credit: © Dr. Dennis Kunkel/Visuals Unlimited

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Bacterial ReproductionBacterial Reproduction

Bacterial reproductionBacterial reproduction

Cellular organism copies it’s genetic information then splits into two identical daughter cells

ConjugationConjugation

http://images.google.com/imgres?imgurl=http://content.answers.com/main/content/wp/en/thumb/0/02/350px-BacterConjugation.png&imgrefurl=http://www.answers.com/topic/bacterial-conjugation&h=410&w=350&sz=75&hl=en&start=1&tbnid=JeAQL49IMC-LqM:&tbnh=125&tbnw=107&prev=/images%3Fq%3Dconjugation%26gbv%3D2%26hl%3Den

Bacterial reproductionBacterial reproduction

http://images.google.com/imgres?imgurl=http://www.drnatura.com/img/good_bad_bacteria.jpg&imgrefurl=http://www.drnatura.com/flora_protect.php&h=248&w=389&sz=44&hl=en&start=3&tbnid=oCRN34FnS1MmzM:&tbnh=78&tbnw=123&prev=/images%3Fq%3Dgood%2Bbacteria%2Bin%2Bcolon%26gbv%3D2%26hl%3Den

Good Bacteria

Good causing bacteriaGood causing bacteria E. Coli in stomach aids digestionE. Coli in stomach aids digestion Benefit soilBenefit soil NitrificationNitrification DecompositionDecomposition Make acetone or butanolMake acetone or butanol To produce insulin, other chemicalsTo produce insulin, other chemicals Clean oil spillsClean oil spills To clean oreTo clean ore Yogurt, cheese, olives, vinegar, sourdoughYogurt, cheese, olives, vinegar, sourdough

Disease causing bacteriaDisease causing bacteria

Way 1: metabolize their host (destroy host Way 1: metabolize their host (destroy host cells)cells)

Way 2: secrete poison as waste productWay 2: secrete poison as waste product

TUBERCULOSISTUBERCULOSIS

STREP THROATSTREP THROAT

LYME DISEASELYME DISEASE

This bacteria can causes toxic shock syndrome (tampon use) and can also cause impetigo and pyoderma and is common in infant day care centers. SEM.

Credit: © Dr. Gary Gaugler/Visuals Unlimited

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Staphylococcus aureus

ArchaeabacteriaArchaeabacteria

Pathogens & EvolutionPathogens & Evolution

Pathogens, like bacteria are living organisms our Pathogens, like bacteria are living organisms our bodies and antibiotics kill like streptococcus. bodies and antibiotics kill like streptococcus. Penicillin when first created was considered the Penicillin when first created was considered the miracle drug as it killed so many bacterial miracle drug as it killed so many bacterial infections. However these bacteria are living infections. However these bacteria are living organisms and wanted to live so they organisms and wanted to live so they evolved/adapted to the drug so that penicillin evolved/adapted to the drug so that penicillin won’t hurt them. Thus doctors must create new won’t hurt them. Thus doctors must create new antibiotics once a pathogen adapts to an old antibiotics once a pathogen adapts to an old antibiotic.antibiotic.