Micro-organismsMicro-organisms

Unit 7Unit 7

Germ TheoryGerm Theory

Proposed by Proposed by Scientist: Luis PasteurScientist: Luis Pasteur..

All All diseases are caused by small diseases are caused by small organisms that can only be seen with organisms that can only be seen with a microscopea microscope..

Led to the discovery of Led to the discovery of pathogens pathogens (germs)(germs) – Bacterial PathogensBacterial Pathogens– Viral PathogensViral Pathogens

Kingdom Monera: BacteriaKingdom Monera: Bacteria Basic infoBasic info

Cell Number: Single-celledCell Number: Single-celled

Cell Type: ProkaryoticCell Type: Prokaryotic

Feeding: Hetero OR Feeding: Hetero OR AutotrophicAutotrophic

Reproduction: Mostly Reproduction: Mostly asexual reproductionasexual reproduction

Appeared 3.5 billion years Appeared 3.5 billion years agoago

2 Domains2 Domains– ArchaebacteriaArchaebacteria– EubacteriaEubacteria

ArchaebacteriaArchaebacteriaPrimitive bacteria that Primitive bacteria that live in harsh live in harsh conditions. conditions.

3 types3 types– MethanogensMethanogens

Convert hydrogen and Convert hydrogen and carbon dioxide to carbon dioxide to MethaneMethane

– Extreme halophilesExtreme halophilesHigh salt concentrationHigh salt concentration

– ThermoacidophilesThermoacidophilesHigh acid or high High acid or high temperaturetemperature

EubacteriaEubacteriaModern Bacteria Modern Bacteria classified by shape classified by shape and reaction to and reaction to Gram stainGram stain– Bacilli: rodBacilli: rod– Spirilla: spiralSpirilla: spiral– Cocci: roundCocci: round– Diplo: pairedDiplo: paired– Strepto: chainsStrepto: chains– Staphylo: clustersStaphylo: clusters

– Gram StainGram StainPositive: purplePositive: purple

Negative: redNegative: red

BACTERIABACTERIA

Structure of BacteriaStructure of Bacteria

Cell membraneCell membrane

CytoplasmCytoplasm

Single Circular Chromosome Single Circular Chromosome

(Sometimes) Endospore(Sometimes) Endospore– Protect cell form harsh climateProtect cell form harsh climate

(Sometimes) Flagella or Cillia(Sometimes) Flagella or Cillia– MovementMovement

Draw and label a simple bacilli Draw and label a simple bacilli bacteria in your notes…bacteria in your notes…

Pathogenic Bacteria Pathogenic Bacteria make you sick!make you sick!

Antibiotics- medicine for treating Antibiotics- medicine for treating diseases caused by bacteriadiseases caused by bacteria– Interfere with cell productionInterfere with cell production– Do not help against viruses!!!!Do not help against viruses!!!!

Antibiotic ResistanceAntibiotic Resistance

Caused by using antibiotics too much Caused by using antibiotics too much or incorrectly or incorrectly – Bacteria evolve (by natural selection) to Bacteria evolve (by natural selection) to

resist the medsresist the meds

New methods or different antibiotics New methods or different antibiotics must be used. must be used.

Antibiotic resistance video…Antibiotic resistance video…

Good Bacteria help you!Good Bacteria help you!

Non-pathogenic bacteria used for…Non-pathogenic bacteria used for…– DigestionDigestion– Sewage breakdownSewage breakdown– Nitrogen cycle (needed plant nutrients)Nitrogen cycle (needed plant nutrients)– Making food (Yogurt and cheese)Making food (Yogurt and cheese)

No Kingdom: VirusesNo Kingdom: Viruses

VirusesViruses

Nonliving infectious particle with a Nonliving infectious particle with a protein coat and a nucleic acid protein coat and a nucleic acid (either DNA or RNA)(either DNA or RNA)

VirologyVirology

Study of virusesStudy of viruses

Late 1800’s people knew that Late 1800’s people knew that “factors” caused disease“factors” caused disease

All viruses are bad, but we learned to All viruses are bad, but we learned to manipulate them for our advantagemanipulate them for our advantage– Tobacco mosaic virus – used for gene Tobacco mosaic virus – used for gene

therapy therapy

Viral ReproductionViral Reproduction

2 cycles – Lytic and Lysogenic2 cycles – Lytic and Lysogenic

Lytic Cycle (Ex: Ebola)Lytic Cycle (Ex: Ebola)

Present in virulent (fast) virusesPresent in virulent (fast) viruses– 1. Attach to cell1. Attach to cell– 2. Insert viral DNA into host cell2. Insert viral DNA into host cell– 3. Replicate viral DNA using host cell3. Replicate viral DNA using host cell– 4. Assemble new viruses4. Assemble new viruses– 5. Destroy host cell to release new 5. Destroy host cell to release new

virusesviruses

End product is more viruses and a End product is more viruses and a dead celldead cell

Lysogenic Cycle (Ex: HIV)Lysogenic Cycle (Ex: HIV)Delayed virus cycle; dormant virusesDelayed virus cycle; dormant viruses– First two steps are the same as lyticFirst two steps are the same as lytic– 3. Insert viral DNA into host DNA3. Insert viral DNA into host DNA– 4. Viral DNA is replicated when host cell 4. Viral DNA is replicated when host cell

dividesdivides– 5. Virus enters the lytic cycle at any time to 5. Virus enters the lytic cycle at any time to

kill the cellkill the cell

*Can be manipulated for gene therapy *Can be manipulated for gene therapy by replacing viral DNA with a desired by replacing viral DNA with a desired genegene

Virus CyclesVirus Cycles

Fighting VirusesFighting VirusesImmune system: can fight off most viruses without Immune system: can fight off most viruses without medsmeds

Best treatement option: prevent infection before Best treatement option: prevent infection before exposure with a vaccineexposure with a vaccine of dead/weak viruses of dead/weak viruses; ; body will build immunity;body will build immunity;– Can lead to eradication if everyone is vaccinatedCan lead to eradication if everyone is vaccinated– Doesn’t work post-infectionDoesn’t work post-infection

Antiviral drugs (very rare)Antiviral drugs (very rare)– Interfere with virus replicationInterfere with virus replication– Ex: TamifluEx: Tamiflu