Kingdom Archaebacteria Kingdom Archaebacteria & Kingdom Eubacteria& Kingdom Eubacteria

Chapter 24Chapter 24

Evolution & Evolution & ClassificationClassification

Section 24-1Section 24-1

Evolution & ClassificationEvolution & Classification

Bacteria are Bacteria are microscopic microscopic prokaryotesprokaryotes, , organisms that lack organisms that lack a cell nucleusa cell nucleus

Unlike most Unlike most organisms, organisms, bacteria have few bacteria have few morphological morphological differencesdifferences

Characteristics of ProkaryotesCharacteristics of Prokaryotes Do NOT have a Do NOT have a

membrane-bound membrane-bound nucleusnucleus

Do have a cell Do have a cell membrane, but do membrane, but do NOT have membrane NOT have membrane bound organellesbound organelles

Have ribosomes that Have ribosomes that are different from are different from those of eukaryotesthose of eukaryotes

Smaller than the Smaller than the smallest eukaryotessmallest eukaryotes

UnicellularUnicellular

Kingdoms of BacteriaKingdoms of Bacteria

There are two kingdoms of bacteria There are two kingdoms of bacteria separated based on the ribosomal separated based on the ribosomal RNA sequences.RNA sequences.

a)a) Kingdom ArcheabacteriaKingdom Archeabacteria – the – the “ancient” bacteria that live in very “ancient” bacteria that live in very harsh environmentsharsh environments

b)b) Kingdom EubacteriaKingdom Eubacteria – the “true” – the “true” bacteria that we consider to be germsbacteria that we consider to be germs

Kingdom ArchaebacteriaKingdom Archaebacteria

Do not have Do not have peptidoglycan, peptidoglycan, a a protein-protein-carbohydrate carbohydrate found in the cell found in the cell walls of eubacteriawalls of eubacteria

Live in extreme Live in extreme environments so environments so that is how they that is how they are classifiedare classified

Phylum MethanogensPhylum Methanogens Live in Live in anaerobic, anaerobic,

oxygen free oxygen free environmentsenvironments

Produce methane gas Produce methane gas by converting Hby converting H22 and and COCO22 into CH into CH44, this is a , this is a form of form of chemosynthesischemosynthesis

Live in swamps, Live in swamps, sewage, marshes, sewage, marshes, animal digestive animal digestive tracts.tracts.

Phylum ThermoacidophilesPhylum Thermoacidophiles

Can live in water Can live in water that is extremely that is extremely hot and acidichot and acidic

Found in hot Found in hot springs or springs or hydrothermal ventshydrothermal vents

Use the heat and Use the heat and acids of their acids of their habitat to produce habitat to produce food by food by chemosynthesischemosynthesis

Phylum Extreme HalophilesPhylum Extreme Halophiles

Live in extremely Live in extremely salty conditionssalty conditions

Found in the Great Found in the Great Salt Lake of Utah, Salt Lake of Utah, Dead Sea, and Dead Sea, and Chaplin LakeChaplin Lake

Use the salt in their Use the salt in their environment for environment for energy, a form of energy, a form of chemosynthesis.chemosynthesis.

Kingdom EubacteriaKingdom Eubacteria

Have Have peptidoglycanpeptidoglycan in their cell walls in their cell walls Classified on shapeClassified on shape Classified on how they react to Gram Classified on how they react to Gram

stainingstaining

Eubacteria ShapesEubacteria Shapes

Eubacteria have three Eubacteria have three different shapesdifferent shapes– BacilliBacilli – rod shaped – rod shaped– CocciCocci – sphere shaped – sphere shaped– SpirillaSpirilla – spiral shaped – spiral shaped

Gram StainingGram Staining

A staining technique A staining technique that divides bacteria that divides bacteria into gram-positive and into gram-positive and gram-negativegram-negative

The technique The technique involves staining involves staining bacteria with a purple bacteria with a purple dye and iodine and dye and iodine and rinsing with alcohol rinsing with alcohol then restained with a then restained with a pink dyepink dye

Gram PositiveGram Positive If the cell retains the If the cell retains the

purple color they are purple color they are gram-positivegram-positive and and they have a thick they have a thick peptidoglycan layer in peptidoglycan layer in their cell walltheir cell wall

They are usually They are usually beneficialbeneficial

We usually use them We usually use them to make antibiotics, to make antibiotics, which kill other gram-which kill other gram-positive bacteriapositive bacteria

Gram NegativeGram Negative

If the cell does not If the cell does not retain the purple retain the purple dye but takes on dye but takes on the pink dye it is the pink dye it is gram-negativegram-negative

They have an extra They have an extra layer of lipid on the layer of lipid on the outside of the cell outside of the cell wallwall

They tend to resist They tend to resist antibioticsantibiotics

Phylum CyanobacteriaPhylum Cyanobacteria They are gram-They are gram-

negative bacterianegative bacteria They perform They perform

photosynthesis and photosynthesis and release oxygen so release oxygen so they are aerobicthey are aerobic

Grow in long filaments Grow in long filaments of cellsof cells

Some have Some have heterocystsheterocysts, special , special cells that contain cells that contain enzymes that can fix enzymes that can fix atmospheric nitrogenatmospheric nitrogen

Phylum SpirochetesPhylum Spirochetes

Gram-negative Gram-negative bacteriabacteria

Spiral shaped Spiral shaped heterotrophic heterotrophic bacteriabacteria

Most are aerobic but Most are aerobic but some are anaerobicsome are anaerobic

Move by corkscrew Move by corkscrew rotationrotation

Phylum Gram-positivePhylum Gram-positive

Most are gram-Most are gram-positive to Gram positive to Gram stainstain

They are found in They are found in diseases and food diseases and food materialsmaterials

They can be They can be filamentous or filamentous or single celledsingle celled

Phylum ProteobacteriaPhylum Proteobacteria

The largest and The largest and most diverse most diverse phylumphylum

There are three There are three subphylumssubphylums– EntericEnteric– ChemoautotrophicChemoautotrophic– Nitrogen-fixingNitrogen-fixing

Enteric BacteriaEnteric Bacteria

Gram-negative Gram-negative heterotrophic heterotrophic bacteriabacteria

Inhabit intestinal Inhabit intestinal tracts tracts

Live in aerobic and Live in aerobic and anaerobic anaerobic conditionsconditions

ChemoautotrophsChemoautotrophs

Gram-negative Gram-negative bacteriabacteria

Extract energy Extract energy from oxidizing from oxidizing minerals so by minerals so by chemosynthesischemosynthesis

Nitrogen-fixingNitrogen-fixing Gram-negative Gram-negative

bacteriabacteria Usually grow Usually grow

symbiotically in root symbiotically in root nodules of plantsnodules of plants

Able to convert Able to convert atmospheric nitrogen atmospheric nitrogen into useful compounds into useful compounds such as ammonia and such as ammonia and nitratesnitrates

Need them to build Need them to build amino acids for the amino acids for the building of proteinsbuilding of proteins

Biology of BacteriaBiology of Bacteria

Section 24-2Section 24-2

Bacteria StructureBacteria Structure

Bacteria are Bacteria are typically composed typically composed of of – Cell wallCell wall– Cell membraneCell membrane– Cytoplasm with Cytoplasm with

ribosomesribosomes– Chromosome Chromosome

(a) Cell Wall(a) Cell Wall

Eubacteria cell Eubacteria cell walls are made of walls are made of peptidoglycanpeptidoglycan

Archeabacteria cell Archeabacteria cell walls are walls are composed of a composed of a different different compound related compound related to cellulose and to cellulose and chitinchitin

(b) Cell Membrane(b) Cell Membrane The cell membrane is composed of a lipid bilayerThe cell membrane is composed of a lipid bilayer The cell membrane has special enzymes for The cell membrane has special enzymes for

carrying out cellular respiration and carrying out cellular respiration and photosynthesisphotosynthesis

The membrane of photosynthetic bacteria have The membrane of photosynthetic bacteria have folds called folds called thylakoidsthylakoids like those in chloroplasts like those in chloroplasts

(c) Cytoplasm(c) Cytoplasm

Bacterial cells do Bacterial cells do not have not have membrane bound membrane bound organelles organelles

The cytoplasm of The cytoplasm of bacterial cells is bacterial cells is made of a viscous made of a viscous solution of solution of ribosomes and ribosomes and DNADNA

(d) Capsule(d) Capsule Many bacteria have an Many bacteria have an

outer covering called a outer covering called a capsulecapsule

The capsule is made of The capsule is made of polysaccharides that cling polysaccharides that cling to the surface of the cell to the surface of the cell and protect it against and protect it against drying out or harsh drying out or harsh chemicalschemicals

When a capsule consists of When a capsule consists of a fuzzy coat of sticky a fuzzy coat of sticky sugars, it is called a sugars, it is called a glycocalyxglycocalyx

The glycocalyx enables the The glycocalyx enables the bacteria to attach to the bacteria to attach to the surface of host cells and surface of host cells and tissuestissues

(e) Pili(e) Pili

Pili Pili are short, hairlike are short, hairlike protein structures protein structures found on the surface found on the surface of some species of of some species of bacteriabacteria

Pili help bacteria hold Pili help bacteria hold on to host cells and on to host cells and are also used for are also used for transfer of genetic transfer of genetic material from one material from one bacterium to anotherbacterium to another

(f) Endospores(f) Endospores When living conditions When living conditions

for the bacterium for the bacterium become unfavourable, become unfavourable, some bacteria form some bacteria form special, dehydrated cells special, dehydrated cells called called endosporesendospores

Endospores consist of a Endospores consist of a thick outer covering that thick outer covering that surrounds the cell’s DNAsurrounds the cell’s DNA

When conditions become When conditions become favorable the favorable the endospores break open endospores break open and produce new and produce new bacterial cellsbacterial cells

(g) Flagella(g) Flagella

Many bacteria use Many bacteria use flagellaflagella, whiplike , whiplike structures that are structures that are used for movementused for movement

Those that do not Those that do not have flagella use have flagella use slime to glide slime to glide through or a through or a corkscrew rotationcorkscrew rotation

Nutrition of BacteriaNutrition of Bacteria

Most bacteria are Most bacteria are heterotrophsheterotrophs, they , they get their energy by get their energy by consuming organic consuming organic matter as a source matter as a source of nutritionof nutrition

Heterotrophs that Heterotrophs that feed on dead or feed on dead or decaying material decaying material are called are called saprophytessaprophytes

Nutrition of BacteriaNutrition of Bacteria

Some bacteria are Some bacteria are autotrophsautotrophs, organisms , organisms capable of creating capable of creating their own food energytheir own food energy– PhotosyntheticPhotosynthetic – use – use

sunlight to create food sunlight to create food energyenergy

– ChemosyntheticChemosynthetic – use – use the energy from the energy from oxidizing inorganic oxidizing inorganic compounds to create compounds to create food energy food energy

Respiration in BacteriaRespiration in Bacteria The type of cellular The type of cellular

respiration is another respiration is another difference between difference between bacteria groupsbacteria groups

Organisms that use Organisms that use oxygen during cellular oxygen during cellular respiration are respiration are aerobesaerobes..

Organisms that do not Organisms that do not use oxygen during use oxygen during cellular respiration are cellular respiration are anaerobesanaerobes

Respiration in BacteriaRespiration in Bacteria The presence or The presence or

absence of oxygen in absence of oxygen in the environment is the environment is one way to distinguish one way to distinguish between different between different bacteriabacteria– Bacteria called Bacteria called obligate obligate

aerobesaerobes cannot live cannot live without oxygenwithout oxygen

– Bacteria called Bacteria called obligate obligate anaerobesanaerobes cannot live cannot live in the presence of in the presence of oxygenoxygen

– Bacteria called Bacteria called facultative anaerobesfacultative anaerobes can use oxygen when it can use oxygen when it is available but they do is available but they do not depend on itnot depend on it

Reproduction in BacteriaReproduction in Bacteria

Most bacteria Most bacteria reproduce by reproduce by binary fissionbinary fission, a , a process in which process in which the chromosome the chromosome replicates then the replicates then the cell dividescell divides

Binary fission is a Binary fission is a type of asexual type of asexual reproductionreproduction

Genetic Recombination in BacteriaGenetic Recombination in Bacteria

Genetic Genetic recombinationrecombination is a is a nonreproductive nonreproductive means by which means by which bacteria acquire bacteria acquire new combinations new combinations of genesof genes

There are three There are three special ways that special ways that bacteria exchange bacteria exchange genesgenes

ConjugationConjugation

The process of The process of exchanging genetic exchanging genetic material through material through cell to cell contact cell to cell contact by a conjugation by a conjugation bridge from the pilibridge from the pili

During conjugation During conjugation DNA moves from DNA moves from one bacterium to one bacterium to another.another.

TransformationTransformation

The process by The process by which bacteria which bacteria cells pick up and cells pick up and incorporate DNA incorporate DNA from dead bacteria from dead bacteria cells.cells.

They take up DNA They take up DNA from dead cells of from dead cells of the same or closely the same or closely related species.related species.

TransductionTransduction

The process by The process by which the transfer which the transfer of DNA from one of DNA from one bacteria to another bacteria to another is done by viruses.is done by viruses.

Viruses called Viruses called bacteriophages are bacteriophages are used to carry DNA used to carry DNA between cellsbetween cells

Bacteria and HumansBacteria and Humans

Section 24-3Section 24-3

Bacteria and DiseaseBacteria and Disease The scientific study of The scientific study of

disease is called disease is called pathologypathology..

Bacteria that cause Bacteria that cause disease are called disease are called pathogens.pathogens.

Some bacteria cause Some bacteria cause disease by producing disease by producing toxinstoxins– ExotoxinsExotoxins are toxins are toxins

that are secreted into that are secreted into the environment by the the environment by the bacteriumbacterium

– EndotoxinsEndotoxins are toxins are toxins are toxins that are are toxins that are released once the released once the bacterium diesbacterium dies

AntibioticsAntibiotics AntibioticsAntibiotics are are

drugs that fight drugs that fight bacteria by bacteria by interfering with interfering with their cellular their cellular functions.functions.

Many antibiotics Many antibiotics are able to affect a are able to affect a wide variety of wide variety of organisms, they organisms, they are called are called broad broad spectrum spectrum antibioticsantibiotics

Antibiotic ResistanceAntibiotic Resistance When a population of bacteria is exposed to an antibiotic, When a population of bacteria is exposed to an antibiotic,

the most susceptible die. A few mutant bacteria are the most susceptible die. A few mutant bacteria are resistant to the antibiotic and continue to grow.resistant to the antibiotic and continue to grow.

A resistant population then grows from these mutant A resistant population then grows from these mutant bacteria and these new populations are bacteria and these new populations are antibiotic resistantantibiotic resistant

This results from over use of antibiotics.This results from over use of antibiotics.

Useful BacteriaUseful Bacteria

Bacteria are used in Bacteria are used in sewage treatment, sewage treatment, and as decomposers, and as decomposers, breaking down the breaking down the remains of organic remains of organic matter in dead plant matter in dead plant and animal wastes. and animal wastes. They are recyclers the They are recyclers the return nutrients back return nutrients back to the environment.to the environment.

Useful BacteriaUseful Bacteria

Bacteria are useful Bacteria are useful in food production.in food production.

Bacteria help us Bacteria help us make buttermilk, make buttermilk, sour cream, sour cream, yogurt, cottage yogurt, cottage cheese, sauerkraut cheese, sauerkraut and pickles.and pickles.

Useful BacteriaUseful Bacteria

Bacteria are also used Bacteria are also used in industrial chemical in industrial chemical production.production.

They produce organic They produce organic chemicals and fuels.chemicals and fuels.

They are used in They are used in mining of mineralsmining of minerals

They are used as They are used as insecticides.insecticides.

Useful BacteriaUseful Bacteria

Bacteria are used Bacteria are used to help clean up to help clean up environmental environmental disaster caused by disaster caused by human such as human such as chemical and oil chemical and oil spills.spills.