Identifying and Identifying and Classifying BacteriaClassifying Bacteria

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 How big is a prokaryotic cell?cell?

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

ClassificationClassification

Archae vs Bacteria Archae vs Bacteria

ArchaeArchae

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 COand CO22 into methane gas for into methane gas for energyenergy

HalophilesHalophiles: love salt: love salt ThermoacidophilesThermoacidophiles: love : love

heat and acidheat and acid

Bacteria:Bacteria:

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

Example: E. coliExample: E. coli

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 : whip-like

structure used to propel structure used to propel bacteriabacteria

SlimeSlime: glide along slime : glide along slime secretionsecretion

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

3. Metabolism: Oxygen or 3. Metabolism: Oxygen or NOTNOT

Obligate Aerobes: Need Obligate Aerobes: Need oxygenoxygen

Obligate Anaerobes: Obligate Anaerobes: cannot live in oxygencannot live in oxygen

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

3.Metabolism: Obtaining 3.Metabolism: Obtaining EnergyEnergyAutotroph vs. HeterotrophAutotroph vs. Heterotroph• Photoautotroph-Photoautotroph- uses light uses light

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

energy from inorganic energy from inorganic chemicals for chemicals for chemosynthesischemosynthesis

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

• Heterotroph – consumes Heterotroph – consumes organic compounds organic compounds

Bacterial ReproductionBacterial Reproduction

Asexual: Binary fissionAsexual: Binary fission

1.1. CircularCircular DNA replicates DNA replicates

2.2. Cell membrane and cell Cell membrane and cell wall 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 approximately every 20 minutesevery 20 minutes

DiseaseDisease

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

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

Gram-staining TestGram-staining Test

Gram-positive: bacteria Gram-positive: bacteria contain contain lotslots of peptidoglycan of peptidoglycan in cell walls. Stains in cell walls. Stains purplepurple..

Gram- negative: bacteria Gram- negative: bacteria contain contain littlelittle peptidoglycan peptidoglycan in cell walls. Stains in cell walls. Stains redred..

ExotoxinsExotoxins

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

For exampleFor example Clostridium tetaniClostridium tetani secretes an secretes an

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

muscles.muscles. Clostridium Clostridium botulinumbotulinum

produces a very powerful produces a very powerful exotoxin that causes the fatal exotoxin that causes the fatal disease, 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, Gram-negative bacteria, that are poisonous.that 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 are endotoxin producing bacteria.producing bacteria.

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

AntibioticsAntibiotics Antibiotics Antibiotics interfereinterfere with with

the bacteria’s cellular the bacteria’s cellular activitiesactivities..

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

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

TetracylineTetracyline: : blocks blocks protein synthesis.protein synthesis.

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

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

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

Antibiotic-ResistanceAntibiotic-Resistance Bacteria can quickly Bacteria can quickly adaptadapt

to their environment to their environment because of their because of 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 antibiotics, bacteria not resistant resistant diedie

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