Bacteria= Ch 23Bacteria= Ch 23

Comparing size:Comparing size:Virus vs. BacteriaVirus vs. Bacteria

Size: Size: Bacteria on the Head Bacteria on the Head of a Pencilof a Pencil

Three Domains of Living Three Domains of Living OrganismsOrganisms

• No peptidoglycan in cell wallNo peptidoglycan in cell wall

– (protein/carb complex to make cell wall rigid)(protein/carb complex to make cell wall rigid)

• Different types of lipids & amino acids in Different types of lipids & amino acids in

cell memb cell memb

• Genes DO have intronsGenes DO have introns

Domain ArchaeDomain Archae

• Many live in extreme environmentsMany live in extreme environments

– HalophilesHalophiles: “salt-loving” found in Great Lake & Dead : “salt-loving” found in Great Lake & Dead

SeaSea

– MethanogensMethanogens: convert H: convert H22 and CO and CO22 into methane, in the into methane, in the

guts of cattle & termitesguts of cattle & termites

– ThermoacidophilesThermoacidophiles: hot/acidic environs like hot springs: hot/acidic environs like hot springs

Domain ArchaeDomain Archae

Domain: BacteriaDomain: Bacteria• Taxonomy is poorTaxonomy is poor• Three major shapesThree major shapes– CocciCocci = sphere = sphere

• Streptococci = chainsStreptococci = chains• Staphylococci = clustersStaphylococci = clusters

– SpirillumSpirillum = spiraled = spiraled

– BacillusBacillus = rod-like = rod-like

Gram StainingGram Staining

• Gram Positive BacteriaGram Positive Bacteria

– Thick peptidoglycanThick peptidoglycan

– Stain purpleStain purple

• Gram NegativeGram Negative

BacteriaBacteria

– Thin peptidoglycanThin peptidoglycan

– Stain pinkStain pink

– Outer membrane = Harder to treat with Outer membrane = Harder to treat with

antibioticsantibiotics

Cell WallsCell Walls

• Cyanobacteria/blue-green algaeCyanobacteria/blue-green algae

– PhotosyntheticPhotosynthetic

• SpirocheteSpirochete

– Gram negativeGram negative

– Spiral shapedSpiral shaped

– Can live freely or be pathogens (Lyme disease, syphilis)Can live freely or be pathogens (Lyme disease, syphilis)

• ChlamydiaChlamydia

– Gram neg.Gram neg.

– CoccoidCoccoid

– Live only inside animal cellsLive only inside animal cells

– Cause STD chlamydiaCause STD chlamydia

Important Bacterial GroupsImportant Bacterial Groups

• Have cell membrane + cell Have cell membrane + cell

wall + cytoplasm + wall + cytoplasm +

ribosomesribosomes

• No membrane-bound No membrane-bound

organellesorganelles

• NO NUCLEAR MEMBRANENO NUCLEAR MEMBRANE

–Circular DNA in mid-cellCircular DNA in mid-cell

Structure & FunctionStructure & Function

• CapsuleCapsule-carbohydrate coat that protects-carbohydrate coat that protects

• PiliPili- short hair-like structures used for - short hair-like structures used for

attachment/ genetic transferattachment/ genetic transfer

• EndosporesEndospores: protect the DNA from harsh : protect the DNA from harsh

environments : only gram +environments : only gram +

• PlasmidPlasmid: small, circular, self-replicating : small, circular, self-replicating

loop of DNAloop of DNA

Other StructuresOther Structures

General StructureGeneral Structure

• May have none, single, double, tufts, or May have none, single, double, tufts, or be surrounded by thembe surrounded by them

• Help in movementHelp in movement

Bacterial FlagellaBacterial Flagella

• Heterotroph: Heterotroph: obtains carbon from other sourcesobtains carbon from other sources• Autotroph: Autotroph: obtain carbon from CO2obtain carbon from CO2• Chemoautotroph: Chemoautotroph: get energy from chemicals in get energy from chemicals in

environ.environ.• Obligate anaerobesObligate anaerobes - cannot live w/ oxygen - cannot live w/ oxygen• Facultative anaerobesFacultative anaerobes - can be aerobic or anaerobic - can be aerobic or anaerobic• Obligate aerobesObligate aerobes - cannot live without oxygen - cannot live without oxygen• SaprophyteSaprophyte - feeds on dead/decaying matter - feeds on dead/decaying matter

Nutrition/MetabolismNutrition/Metabolism

• TransformationTransformation - Takes up DNA from environment - Takes up DNA from environment

• ConjugationConjugation - Transfer of plasmid between - Transfer of plasmid between

bacteriabacteria

• TransductionTransduction - A virus - A virus

transfers bacterial DNA transfers bacterial DNA

Reproduction & RecombinationReproduction & Recombination

• Destroy cell tissuesDestroy cell tissues

• Produce toxinsProduce toxins

–ExotoxinsExotoxins - protein produced by - protein produced by gram +gram + bacteria, bacteria,

secrete toxin into environment secrete toxin into environment

–EndotoxinEndotoxin - lipids & carbs produced by - lipids & carbs produced by gram -gram -

bacteria, released upon bacterial deathbacteria, released upon bacterial death

How bacteria cause How bacteria cause diseasedisease

Bacterial DiseasesBacterial Diseases

• Natural selection favors resistant bacteriaNatural selection favors resistant bacteria

• Mutations can confer resistance to an antibioticMutations can confer resistance to an antibiotic

• Mutant cells take over popl, while the rest dieMutant cells take over popl, while the rest die

• Take all prescribed antibioticsTake all prescribed antibiotics

• Causing an increased number of bacterial diseases Causing an increased number of bacterial diseases

because of resistancebecause of resistance

Antibiotic ResistanceAntibiotic Resistance

Useful BacteriaUseful Bacteria• BioremediationBioremediation

• Use of bacteria & microorganisms Use of bacteria & microorganisms to digest waste to digest waste

• Takes Takes longer to longer to work but work but is VERY is VERY cheap to cheap to use use

• Nutrient RecyclerNutrient Recycler

• Nitrogen FixersNitrogen Fixers

– important in nitrogen cycleimportant in nitrogen cycle

• Make food & drugsMake food & drugs

– Yogurt, pickles, insulinYogurt, pickles, insulin

• Cook food thoroughly to avoid bacterial illnessCook food thoroughly to avoid bacterial illness

Helpful BacteriaHelpful Bacteria

Viruses= Ch 24Viruses= Ch 24

• Discovered in late 1800’sDiscovered in late 1800’s

• 1935 Wendell Stanley discovered TMV, virus that 1935 Wendell Stanley discovered TMV, virus that

causes disease in tobacco & tomato plantscauses disease in tobacco & tomato plants

• SizeSize

– smaller than bacteriasmaller than bacteria

• DO NOT have all characteristics necessary for lifeDO NOT have all characteristics necessary for life

VirusesViruses

• StructureStructure

– Nucleic acid (DNA or RNA) covered Nucleic acid (DNA or RNA) covered

by a protein coat (capsid)by a protein coat (capsid)

– Some have an envelope outside Some have an envelope outside

capsidcapsid

VirusesViruses

• DNA or RNADNA or RNA

• Circular or linear DNA or RNACircular or linear DNA or RNA

• Double or single stranded DNA or RNADouble or single stranded DNA or RNA

• Capsid shapeCapsid shape

• Envelope presenceEnvelope presence

Virus ClassificationVirus Classification

• OptionsOptions

– Enter host directly & produce mRNAEnter host directly & produce mRNA

– Insert into host’s c’some & get transcribed to Insert into host’s c’some & get transcribed to

RNA w/ host DNA (provirus)RNA w/ host DNA (provirus)

Viral (DNA) ReplicationViral (DNA) Replication

• OptionsOptions

– RNA genome can be immediately translated to make RNA genome can be immediately translated to make

viral proteins & more virusesviral proteins & more viruses

– RETROVIRUSES use RETROVIRUSES use reverse transcriptasereverse transcriptase and RNA as and RNA as

template to make DNA, which is then used to produce template to make DNA, which is then used to produce

viral RNA and proteinsviral RNA and proteins

Viral (RNA) ReplicationViral (RNA) Replication

• Virus that infects bacteriaVirus that infects bacteria

BacteriophageBacteriophage

Viral ReproductionViral Reproduction

• Lytic Cycle-INFECT AUTOMATICALLY!Lytic Cycle-INFECT AUTOMATICALLY!

– Virus replicates inside cellVirus replicates inside cell

– Cell bursts releasing lots of viruses immediatelyCell bursts releasing lots of viruses immediately

– destroys hostdestroys host

• Lysogenic Cycle-LAY DORMANT (ASLEEP)Lysogenic Cycle-LAY DORMANT (ASLEEP)

– Viral DNA is incorporated into host DNAViral DNA is incorporated into host DNA

– As cell replicates so does viral DNAAs cell replicates so does viral DNA

– Does not kill the cell (temperate) until it enters lytic cycleDoes not kill the cell (temperate) until it enters lytic cycle

Viral ReplicationViral Replication

Viruses & Human DiseaseViruses & Human Disease

• VectorsVectors: Transmit disease: Transmit disease

– Animals, humans, insectsAnimals, humans, insects

Human Viral DiseasesHuman Viral Diseases

• Viral HepatitisViral Hepatitis

– Inflammation of the liver, can be caused by at least 5 virusesInflammation of the liver, can be caused by at least 5 viruses

– A & E can be spread by fecally contaminated food/waterA & E can be spread by fecally contaminated food/water

– B,C,D spread by sexual contact, infected blood & serum, contaminated needlesB,C,D spread by sexual contact, infected blood & serum, contaminated needles

• Human Immunodeficiency Virus (HIV) Human Immunodeficiency Virus (HIV)

– RNA virus spread by sexual contact, contact w/ infected body fluids, mother to fetusRNA virus spread by sexual contact, contact w/ infected body fluids, mother to fetus

– Damages bodys immune systemDamages bodys immune system

– Disease is called Acquired Immune Deficiency Syndrome Disease is called Acquired Immune Deficiency Syndrome (AIDS)(AIDS)

Human Viral DiseasesHuman Viral Diseases

HIV and AIDSHIV and AIDS

• Viruses & CancerViruses & Cancer

– Some viruses have oncogenes that cause Some viruses have oncogenes that cause

cancercancer

– Some viruses convert protooncogenes (control Some viruses convert protooncogenes (control

cell growth) into oncogenescell growth) into oncogenes

Human Viral DiseasesHuman Viral Diseases

• Usually infect animals isolated in nature but Usually infect animals isolated in nature but

can “jump” to humans when contact occurscan “jump” to humans when contact occurs

– Ex: EbolaEx: Ebola

Emerging Viral DiseasesEmerging Viral Diseases

• VaccinationVaccination (MMR, Hepatitis, Chickenpox) (MMR, Hepatitis, Chickenpox)

– Inactivated - do not replicateInactivated - do not replicate

– Attenuated - are incapable of causing diseaseAttenuated - are incapable of causing disease

• Vector ControlVector Control: kill mosquitoes, quarantine ill patients: kill mosquitoes, quarantine ill patients

• Drug TherapyDrug Therapy

– Antiviral drugsAntiviral drugs (AZT) - interfere with viral nucleic acid synthesis (AZT) - interfere with viral nucleic acid synthesis

– Protease InhibitorProtease Inhibitor - interferes with protein cap synthesis - interferes with protein cap synthesis

Prevention & TreatmentPrevention & Treatment

• Simpler than a virusSimpler than a virus

• Can cause diseasesCan cause diseases

• ViroidsViroids

– Short single strand of RNA - no capsidShort single strand of RNA - no capsid

– disrupt cell metabolismdisrupt cell metabolism

– Affect plantsAffect plants

• PrionsPrions

– Abnormal proteins that clump Abnormal proteins that clump

– Affect animalsAffect animals

– Mad Cow DiseaseMad Cow Disease

Viroid & PrionsViroid & Prions

CH 47 CH 47 The Body’s Defense The Body’s Defense

SystemsSystems

Identifying PathogensIdentifying Pathogens• PathogenPathogen

– Any agent that causes disease & can be spread to humans through Any agent that causes disease & can be spread to humans through

air, food, water, direct contact w/ infected individualair, food, water, direct contact w/ infected individual

• Disease caused by a pathogen is called an Disease caused by a pathogen is called an infectious infectious

diseasedisease

• Koch’s postulatesKoch’s postulates are “rules” for identifying particular are “rules” for identifying particular

pathogenpathogen

Koch’s PostulatesKoch’s Postulates

• Nonspecific DefensesNonspecific Defenses

• SkinSkin

– releases sweat, oils, waxesreleases sweat, oils, waxes

– it’s a tough physical barrier when intactit’s a tough physical barrier when intact

– has good bacteria on surface has good bacteria on surface

• Mucous membranesMucous membranes

– Epithelial tissueEpithelial tissue

– protect interior surfaces of bodyprotect interior surfaces of body

– secrete secrete mucusmucus to trap pathogens to trap pathogens

11stst line of defense: Barriers line of defense: Barriers

• If pathogen gets past 1If pathogen gets past 1stst defenses then defenses then

22ndnd line is activated line is activated

• Works the same for all pathogensWorks the same for all pathogens

• Includes “Includes “inflammatory responseinflammatory response””

22ndnd line of defense: line of defense: nonspecific immunitynonspecific immunity

• Series of events that suppress infection & speed Series of events that suppress infection & speed

recoveryrecovery

– Histamine release: chemical released by damaged cell. Histamine release: chemical released by damaged cell.

Increases blood flow & permeability of surrounding capillariesIncreases blood flow & permeability of surrounding capillaries

– Increase in WBC’s (phagocytes)and fluids = redness, swellingIncrease in WBC’s (phagocytes)and fluids = redness, swelling

• PhagocytesPhagocytes: ingest & destroy foreign matter: ingest & destroy foreign matter

Inflammatory ResponseInflammatory Response

Inflammatory ResponseInflammatory Response

• Phagocytes - Phagocytes - engulfersengulfers

– neutrophil - most common engulf pathogenneutrophil - most common engulf pathogen

– macrophage - engulf pathogen macrophage - engulf pathogen & & old cell stuffold cell stuff

– May trigger B or T lymphocytesMay trigger B or T lymphocytes

– Express foreign antigens on their surfaceExpress foreign antigens on their surface

• Natural Killer CellsNatural Killer Cells - kill infected cells - kill infected cells

– good cancer and virus fighters good cancer and virus fighters

White Blood CellsWhite Blood Cells

• Proteins = Complement systemProteins = Complement system

– Some circulate in bloodstream & become active when Some circulate in bloodstream & become active when

they encounter certain pathogensthey encounter certain pathogens

– Ex: Ex: interferoninterferon: released by cells infected w/ viruses, : released by cells infected w/ viruses,

enables nearby cells to resist viral infectionenables nearby cells to resist viral infection

22ndnd line: nonspecific line: nonspecific immunityimmunity

• Temperature responseTemperature response

– Fever: increase in body temp.Fever: increase in body temp.

– Slows bacterial growth & promotes WBC activitySlows bacterial growth & promotes WBC activity

– Moderate are helpful, too high = dangerousModerate are helpful, too high = dangerous

22ndnd line: nonspecific line: nonspecific immunityimmunity

• Used when pathogens escape the non Used when pathogens escape the non

specific (1specific (1stst & 2 & 2ndnd line) defenses line) defenses

• Lymphocytes - WBC’s Lymphocytes - WBC’s in blood, spleen, lymph, in blood, spleen, lymph,

lymph nodeslymph nodes

– B cells: made in bone marrow and mature B cells: made in bone marrow and mature

there or in spleen. there or in spleen. MAKE ANTIBODIESMAKE ANTIBODIES

– T cells : made in bone marrow mature in T cells : made in bone marrow mature in

thymusthymus

– B & T help develop immunityB & T help develop immunity

Specific Defenses: the immune systemSpecific Defenses: the immune system

• AntigenAntigen: substance that triggers an : substance that triggers an

immune response (bacteria, pollen, venom)immune response (bacteria, pollen, venom)

• LymphocytesLymphocytes have specific receptors to have specific receptors to

find an antigen (you have millions of types find an antigen (you have millions of types

of lymphocytes)of lymphocytes)

• If lymphocytes don’t recognize antigen, If lymphocytes don’t recognize antigen,

they initiate immune responsethey initiate immune response

Recognizing PathogensRecognizing Pathogens

Recognizing PathogensRecognizing Pathogens

• Simultaneous “2 pronged” attackSimultaneous “2 pronged” attack

• ““HumoralHumoral” and “” and “cell-mediatedcell-mediated” response” response

• T cells activate proteins (T cells activate proteins (cytokinescytokines) that ) that

affect the behavior of other immune cellsaffect the behavior of other immune cells

Immune ResponseImmune Response

• Cytokines activate Helper T cells & Cytokines activate Helper T cells &

Cytotoxic T cellsCytotoxic T cells

• Involves T cellsInvolves T cells

– HelperHelper T cells – produce memory T cells T cells – produce memory T cells

– Killer Killer T cells (cytotoxic) - destroy infected T cells (cytotoxic) - destroy infected

cellscells

– SupressorSupressor T cells - shuts down immune T cells - shuts down immune

response when saferesponse when safe

– MemoryMemory T Cells- imp. For 2 T Cells- imp. For 2ndnd exposure exposure

Cell-Mediated Immune ResponseCell-Mediated Immune Response

• Involves B cells Involves B cells

• Responds to antigens, produces antibodiesResponds to antigens, produces antibodies

• AntibodyAntibody: defensive protein that reacts to a specific antigen: defensive protein that reacts to a specific antigen

• Helper T cell stimulates production of Helper T cell stimulates production of B cells/lymphocytesB cells/lymphocytes, which then , which then

form into antibody releasing form into antibody releasing plasma cellsplasma cells

• Antibodies inactivate or trigger destruction of pathogen by nonspecific Antibodies inactivate or trigger destruction of pathogen by nonspecific

defensesdefenses

• Memory B cellsMemory B cells – 2 – 2ndnd exposure exposure

Humoral Immune ResponseHumoral Immune Response

• First time antigen is encountered = primary First time antigen is encountered = primary

response, memory cells are producedresponse, memory cells are produced

• Next time antigen is encountered Next time antigen is encountered

(secondary resp.), faster response because (secondary resp.), faster response because

of “of “memory cells” memory cells”

Primary and Secondary ResponsesPrimary and Secondary Responses

• Immunity: ability to resist an infectious Immunity: ability to resist an infectious

diseasedisease

– Comes from: surviving an initial infection or Comes from: surviving an initial infection or

vaccinationvaccination

• Vaccination initiates a primary response Vaccination initiates a primary response

then memory cells formthen memory cells form

Immunity & VaccinationImmunity & Vaccination

• AllergiesAllergies

– Immune system reacts to a harmless antigen in a way that can be Immune system reacts to a harmless antigen in a way that can be

harmfulharmful

– AsthmaAsthma: can be triggered by allergy: can be triggered by allergy

• Autoimmune DiseaseAutoimmune Disease

– Your immune system reacts to your own cellsYour immune system reacts to your own cells

– multiple sclerosis, lupus, rheumatoid arthritis, Type I diabetesmultiple sclerosis, lupus, rheumatoid arthritis, Type I diabetes

Problems of Immune SystemsProblems of Immune Systems

AllergyAllergy

• Phase IPhase I

– Asymptomatic: few symptomsAsymptomatic: few symptoms

– Viruses increase rapidly b/c of replicationViruses increase rapidly b/c of replication

– May last 10 + yearsMay last 10 + years

• Phase IIPhase II

– Beginning or worsening of symptomsBeginning or worsening of symptoms

– B cells continue making antibodiesB cells continue making antibodies

– T cells steadily declineT cells steadily decline

• Phase IIIPhase III

– # of T helper cells drops to low (< 200/mL ; normal = 640/mL) to stimulate B cells & cytotoxic T cells# of T helper cells drops to low (< 200/mL ; normal = 640/mL) to stimulate B cells & cytotoxic T cells

– AIDS is diagnosed AIDS is diagnosed

– Opportunistic infections occurOpportunistic infections occur

HIV to AIDS 3 stepsHIV to AIDS 3 steps

• By bodily fluids By bodily fluids

containing HIV or HIV containing HIV or HIV

infected cellsinfected cells

• Most commonly through Most commonly through

sexual contact or sexual contact or

contaminated syringescontaminated syringes

• Cannot be transmitted Cannot be transmitted

through casual contactthrough casual contact

Transmission of HIVTransmission of HIV

• Difficult b/c of rapid mutation rateDifficult b/c of rapid mutation rate

• Quickly becomes resistant to antiviral drugsQuickly becomes resistant to antiviral drugs

• Expensive & include multiple drugsExpensive & include multiple drugs

Vaccines & Vaccines & Treatments for HIVTreatments for HIV