Virus & Bacteria UnitVirus & Bacteria Unit

Part 1: VirusesPart 1: Viruses

Big Idea: Big Idea: VIRUSES ARE VIRUSES ARE NOTNOT LIVING LIVING BECAUSE THEY DON’T FULFILL ALL THE BECAUSE THEY DON’T FULFILL ALL THE CHARACTERISTICS OF LIVING THINGS.CHARACTERISTICS OF LIVING THINGS.

DefinitionDefinition

Viruses are Viruses are tiny tiny particles particles unlike any unlike any other organism. other organism.

A virus consists of A virus consists of genetic material such genetic material such as as RNA or DNARNA or DNA wrapped in a protein wrapped in a protein coat.coat.

Characteristics of LifeCharacteristics of Life HomeostasisHomeostasis NutritionNutrition TransportTransport RespirationRespiration SynthesisSynthesis GrowthGrowth ExcretionExcretion RegulationRegulation ReproductionReproduction

Is a virus living?Is a virus living?

Is it living?Is it living?

No, because a virus can not reproduce on No, because a virus can not reproduce on its own. It needs a host cells.its own. It needs a host cells.

How does a virus’ size relate to the How does a virus’ size relate to the size of the cell?size of the cell?

Viruses are much smaller than a cell and Viruses are much smaller than a cell and that is why they can easily get into a cellthat is why they can easily get into a cell

How are viruses characterized?How are viruses characterized?

Characterized as:Characterized as:PlantPlantAnimalAnimalBacterial virusBacterial virus

What are the two parts that What are the two parts that comprise a virus?comprise a virus?

Nucleic Acid Core Nucleic Acid Core (either RNA or DNA)(either RNA or DNA)

Protein Coat called a Protein Coat called a capsidcapsid

Shapes of VirusesShapes of Viruses

1. Rod shaped 1. Rod shaped (tobacco mosaic (tobacco mosaic virus)virus)

Shapes of VirusShapes of Virus

2. Polyhedral 2. Polyhedral (Mumps)(Mumps)

Shapes of VirusShapes of Virus

3. Helical (Herpes)3. Helical (Herpes)

How does a DNA virus replicate?How does a DNA virus replicate?

DNA virus produces RNA (transcription)DNA virus produces RNA (transcription)RNA directs production of viral proteinsRNA directs production of viral proteins

OROR

Viral DNA combines with host cell’s DNAViral DNA combines with host cell’s DNA

How does RNA virus replicate or How does RNA virus replicate or reproduce itself?reproduce itself?

Once inside the host, an RNA virus directs Once inside the host, an RNA virus directs the host cell to produce proteinsthe host cell to produce proteins

OROR

Viral RNA may make DNA Viral RNA may make DNA

Retrovirus Retrovirus

Virus that has RNA as its genetic materialVirus that has RNA as its genetic materialExample is HIVExample is HIV

BacteriophageBacteriophage

Virus that attacks a bacterial cellVirus that attacks a bacterial cell

Two types of infection:Two types of infection:

A.A. Lytic CycleLytic Cycle

B.B. Lysogenic CycleLysogenic Cycle

Lytic CycleLytic Cycle

Bacteriophage attaches to host cell and Bacteriophage attaches to host cell and injects its DNAinjects its DNA

Foreign DNA produces more proteins in Foreign DNA produces more proteins in the host cellthe host cell

Causes cell to lyse (or break open) and Causes cell to lyse (or break open) and the virus/phage is released into the host’s the virus/phage is released into the host’s bodybody

Lytic CycleLytic Cycle

Lysogenic CycleLysogenic Cycle

Bacteriophage injects DNA into the host Bacteriophage injects DNA into the host cellcell

Bacteriophage’s DNA integrates itself into Bacteriophage’s DNA integrates itself into a chromosomea chromosome

Bacteria reproducesBacteria reproduces

Lysogenic CycleLysogenic Cycle

Bacteria UnitBacteria Unit

Big Idea:Big Idea:BACTERIA ARE PROKARYOTIC BACTERIA ARE PROKARYOTIC CELLS THAT HAVE DIFFERENT CELLS THAT HAVE DIFFERENT

SHAPES, STRUCTURES, & SHAPES, STRUCTURES, & FUNCTIONS IN THEIR FUNCTIONS IN THEIR

ENVIRONMENT.ENVIRONMENT.

What is a prokaryote?What is a prokaryote?

Cells that lack a Cells that lack a true nucleustrue nucleus..Cells that lack Cells that lack membrane-membrane-

bound organellesbound organelles..Most surrounded by a cell wall.Most surrounded by a cell wall.Many secrete a Many secrete a protective protective

slime capsuleslime capsule..

How big is a prokaryotic cell?How big is a prokaryotic cell?

1- 5 micrometers1- 5 micrometers(1 millionth of a meter)(1 millionth of a meter)

ClassificationClassification

Archaebacteria vs Eubacteria Archaebacteria vs Eubacteria

ArchaebacteriaArchaebacteria

Surrounded by a cell wall Surrounded by a cell wall lacking lacking peptidoglycanpeptidoglycan..

Live in Live in extreme conditionsextreme conditions

Examples of ArchaeExamples of Archae

Methanogens: Methanogens: convert Hconvert H2 2 and and

COCO22 into methane gas for into methane gas for

energyenergyHalophilesHalophiles: love salt: love saltThermoacidophilesThermoacidophiles: love : love

heat and acidheat and acid

Eubacteria:Eubacteria:

Surrounded by a cell wall Surrounded by a cell wall made of made of peptidoglycanpeptidoglycan..

Example: rhizobium- Example: rhizobium- nitrogen–fixing bacterianitrogen–fixing bacteria

Identifying ProkaryotesIdentifying Prokaryotes

1. Shape:1. Shape:• Coccus – sphericalCoccus – spherical• Bacillus – rod-shapedBacillus – rod-shaped• Spirillum – spiralSpirillum – spiral• Vibrio – comma shapeVibrio – comma shape

Coccus

Spirillum

Vibrio

Bacillus

Ex. Diplococcus

CocciCocci and and BacilliBacilli may may group togethergroup together

Prefixes for arrangements: Diplo – two

Strepto – chainStrepto – chain

Streptococcus

Streptobacillus

Staphylo - clusteredStaphylo - clustered

Staphylococcus

2. Motility: ability to move2. Motility: ability to move

FlagellaFlagella: whip-like structure : whip-like structure used to propel bacteriaused to propel bacteria

SlimeSlime: glide along slime : glide along slime secretionsecretion

Spiral motionSpiral motion: cork-screw : cork-screw motion (spirillum) motion (spirillum)

3. Metabolism: Oxygen or NOT3. Metabolism: Oxygen or NOT

Obligate Aerobes: Need Obligate Aerobes: Need oxygenoxygen

Obligate Anaerobes: cannot Obligate Anaerobes: cannot live in oxygenlive in oxygen

Facultative anaerobes: can Facultative anaerobes: can live with or without oxygenlive with or without oxygen

3.Metabolism: Obtaining Energy3.Metabolism: Obtaining Energy

Autotroph vs. HeterotrophAutotroph vs. Heterotroph• Photoautotroph-Photoautotroph- uses light uses light

energy for photosynthesisenergy for photosynthesis• Chemoautotroph-Chemoautotroph- uses energy uses energy

from inorganic chemicals for from inorganic chemicals for chemosynthesischemosynthesis

• Photoheterotrophs-Photoheterotrophs- uses uses photosynthesis and eats photosynthesis and eats organic compoundsorganic compounds

• Heterotroph – consumes Heterotroph – consumes organic compounds organic compounds

reviewreview

What role do chemosynthetic What role do chemosynthetic bacteria have in the bacteria have in the ecosystem?ecosystem?

http://www.youtube.com/watch?v=4lmwbBzClAc&NR=1

Bacterial ReproductionBacterial Reproduction

Asexual: Binary fissionAsexual: Binary fission

1.1. CircularCircular DNA replicates DNA replicates

2.2. Cell membrane and cell wall Cell membrane and cell wall dividedivide

3.3. IdenticalIdentical daughter cells daughter cells separateseparate

How fast does this happen?How fast does this happen?

http://www.youtube.com/watch?v=gEwzDydciWc&feature=related

approximately every approximately every 20 minutes20 minutes

Genetic recombinationGenetic recombination

Sharing or exchanging of Sharing or exchanging of genetic materialgenetic material

3 types:3 types:

1.1. ConjugationConjugation

2.2. TransformationTransformation

3.3. TransductionTransduction

1. 1. ConjugationConjugationA A temporary temporary bridgebridge forms forms

between two cells.between two cells.A A plasmidplasmid, a separate section of , a separate section of

DNA, is transferred from one cell DNA, is transferred from one cell to the other. to the other.

Often the plasmid contains Often the plasmid contains useful useful genesgenes, like antibiotic resistance. , like antibiotic resistance.

2. 2. TransformationTransformation

Bacteria takes in DNA from the Bacteria takes in DNA from the environmentenvironment..

Dead bacteriaDead bacteria may break apart and may break apart and release DNA.release DNA.

Other bacteria can pick up this DNA Other bacteria can pick up this DNA and become and become genetically different.genetically different.

3. 3. TransductionTransduction

VirusesViruses can pick up small can pick up small amounts of DNA from a amounts of DNA from a host host bacteria.bacteria.

When it When it infectsinfects another another bacteria, the new DNA is bacteria, the new DNA is transferredtransferred into that cell. into that cell.

DiseaseDisease

PathologyPathology is the study of is the study of disease.disease.

PathogensPathogens: organisms that : organisms that cause disease.cause disease.

ExotoxinsExotoxins

Poisonous proteinsPoisonous proteins that are that are released by some gram-released by some gram-positive bacteria.positive bacteria.

For exampleFor exampleClostridium tetaniClostridium tetani secretes an secretes an

exotoxin that causes tetanus.exotoxin that causes tetanus.Tetanus causes stiffness in muscles.Tetanus causes stiffness in muscles.

Clostridium Clostridium botulinumbotulinum produces a produces a very powerful exotoxin that causes very powerful exotoxin that causes the fatal disease, the fatal disease, botulismbotulism..

1 g1 g of botulism toxin can kill of botulism toxin can kill 1 1 millionmillion people. people.

EndotoxinsEndotoxins

LipidsLipids and and carbohydratescarbohydrates in in the cell the cell membranesmembranes of some of some Gram-negative bacteria, that Gram-negative bacteria, that are poisonous.are poisonous.

They are They are releasedreleased when the when the bacteria bacteria diedie. .

For example:For example:

Most species of Most species of SalmonellaSalmonella, , are endotoxin producing are endotoxin producing bacteria.bacteria.

SalmonellaSalmonella typhityphi, , causes causes typhoid fever.typhoid fever.

AntibioticsAntibiotics

Antibiotics Antibiotics interfereinterfere with the with the bacteria’s cellular bacteria’s cellular activitiesactivities..

For example:For example:PenicillinPenicillin: : blocks the building blocks the building

of the cell wallof the cell wall..““Accidently” discovered by Accidently” discovered by Alexander Fleming in 1920sAlexander Fleming in 1920s

TetracylineTetracyline: : blocks protein blocks protein synthesis.synthesis.

Where do antibiotics come from?Where do antibiotics come from?

Antibiotics are naturally made Antibiotics are naturally made by some by some fungifungi and and bacteriabacteria..

Some are made Some are made syntheticallysynthetically in labs.in labs.

But most used in treatment But most used in treatment still come from still come from bacteriabacteria..

Antibiotic-ResistanceAntibiotic-ResistanceBacteria can quickly Bacteria can quickly adaptadapt to to

their environment because of their environment because of their their rapid raterapid rate of of reproductionreproduction..

Antibiotic-ResistanceAntibiotic-Resistance1.1. If one bacterium If one bacterium mutatesmutates and and

becomes becomes resistantresistant, ,

2.2. then in the presence of then in the presence of antibiotics, bacteria not resistant antibiotics, bacteria not resistant diedie

3.3. Those with the resistance take Those with the resistance take over the over the populationpopulation..

Which diseases are preventable Which diseases are preventable by better sanitation practice?by better sanitation practice?

CholeraCholeraSalmonellaSalmonellaTetanusTetanusStaphStaph

What are other ways that antibiotic What are other ways that antibiotic resistance is passed?resistance is passed?

Genetic recombinationGenetic recombination