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ProkaryotesDomain BacteriaDomain Archaebacteria

Common Ancestor

Bacteria Archaea Eukarya

Objectives• Describe the structure, composition, and

functions of prokaryotic cell walls.

• Distinguish, with prokaryotic examples, amongphotoautotrophs, chemoautotrophs,photoheterotrophs, and chemoheterotrophs.

Types of cells What is a cell?• The cell is the structural and functional

unit of all known living organisms.

• It is the smallest unit of an organism thatis classied as living

• The cell theory

• that all living things consist of cells.

• that all cells come from other cells.

• New cells are produced by division ofexisting cells

Limits to cell size

! micron = micrometer = 1/1,000,000 meter ! diameter of human hair = ~20 microns

Size limits for cells

Eukaryotes - >10um

Upper limit – 100um

Lower limit -mycoplasma 0.1um to

1um

Median - 1 - 10um

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Why is a hugesingle-celledcreature not

possible?

How?

B U T …

Pre 19 th Century

+

= Ummm,

I don ʼ t think

sunshine!!!

Louis Pasteur Developed vaccines for anthrax, fowl cholera, andrabies

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Pasteur ʼ s Experiment Common Components of Cells

Plasma Membrane

boundary surrounding the cell

Genetic material: DNA

located somewhere in the cell

Cell membrane• Function

• separates cell from outside• controls what enters or leaves cell

• O2,CO 2, food, H 2O, nutrients, waste• recognizes signals from other cells

• allows communication between cells

• Structure• double layer of fat

• phospholipid bilayer• receptor molecules• proteins

lipid “tail”

phosphate“head”

Wassily Kandinsky (1866-1944)

Coloful Ensemble. 1938. Oil and gloss paint on canvas. 116x 89 cm. Musée National d'Art Moderne, Centre GeorgesPompidou, Paris, France.

cytoplasm

Cytoplasm – liesinternal to

plasmamembrane

Consists of cytosol,organelles, andinclusions

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Mechanisms of Antimicrobial Action

Bacteria have their own enzymes for

Cell wall formation

Protein synthesis

DNA replication

RNA synthesis

Synthesis of essentialmetabolites

Cells aremembrane-enclosed,

DNA-containing,

metabolizing,and self-

replicating

PROKARYOTE

Before Nut

1um 2um 5um

Bacterial shapes

Spirula - spiral

Bacilli – rod

Cocci - spherical

How many bacteria?1000 trillion = ?1000 million million = ?

1,000, 000, 000, 000, 000 = HUH?

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Gram StainPurple are Gram

positive

Pink are Gramnegative

Bacterial Capsule

Capsulesprovide

desiccationresistance,

attachment tosurfaces, andresistance tophagocytosis

Bacterial FimbriaeFibriae areinvolve inbacterial

attachment tosurfaces andresistance tophagocytosis

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Invaginated Plasma membranes

Some prokaryotes displayinvaginated plasma

membranes

This increasesmembrane area, just as

seen, e.g., inmitochondria

Salmonella bacteria withperitrichous agella. TEM

X13,250.

Bacteria

• Flagella• Produce a rotary

motion like a propeller• Go forward by rotating

one direction• Go backwards by

reversing rotation.

Bacterial FlagellaFlagella

effectmotility

Movement can bedown or up

concentrationgradients, e.g.,

toward food

the agellum containsmany parts homologousto other systems

Type III Secretion apparatus

Axial protein family

Ion transport

Type II secretion

Signal transduction

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Prokaryote vs. Eukaryote Chromosome

Conjugation

Sex pili effect the transfer of conjugative plasmids

Comparative Genome Sizes

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Summary of differences!PRO Euks

small cells (< 5 mm) larger cells (> 10 mm)

always unicellular often multicellular

no nucleus or any membrane-boundorganelles

always have nucleus and other membrane-bound organelles

DNA is circular, without proteins DNA is linear and associated with

proteins to form chromatinr ibosomes are small (70S) r ibosomes are large (80S)

no cytoskeleton always has a cytoskeleton

cell division is by binary fission cell division is by mitosis or meiosis

reproduction is always asexual reproduction is asexual or sexual

Sporulation

Bacteria live EVERYWHERE!

• Bacteria live in all ecosystems• on plants & animals• in plants & animals• in the soil• in depths of the oceans• in extreme cold• in extreme hot• in extreme salt• on the living

• on the dead

Nutrition

Photo-autotrophy

Chemo-autotrophy

Chemo- heterotrophy

Oxygen

strict aerobesneed oxygen

strict anaerobeskilled by oxygen

Aerotolerantdon’t use oxygen but willsurvive in it

Facultative anaerobesuse oxygen but don’treally need it

Oxygen Requirements

Pure agar ObligateAerobe

ObligateAnerobe

FacultativeAnerobe

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Bacteria as benecial• Life on Earth is dependent on bacteria

• decomposers• recycling of nutrients from dead to living

• nitrogen xation• only organisms that can x N from

atmosphere

• needed for synthesis of proteins &nucleic acids• plant root nodules

• help in digestion (E. coli)• digest cellulose for herbivores

• cellulase enzyme• produce vitamins K & B12 for humans

Specialized N 2-Fixing Cells

Nitrogen-fixing cells

Cyanobacteria areoxygen-liberating

photosynthetic bacteria

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liver

pancreas

liver

Regulation of Blood Sugar

blood glucose level

insulin

bodycells take

up glucosefrom blood

liver storesglucose asglycogen

reducesappetite

glucagon

pancreas

liver releasesglucose

triggershunger

high

low

Feedback: Maintaining HomeostasisNormal70 and 110 mg/dL

Fred Banting (1891-1941) Charles H. Best (1899-1978) John J.R. McLeod (1876-1935)

James B. Collip(1892-1965)

The Discovery of Insulin (Toronto 1921)

Marjorie (?-?)Patient J.L., December 15, 1922 February 15, 1923

The Miracle of Insulin

Insulin ProductionBegins• First produced as “Connaught”

by the Univ of Toronto• On May 30, 1922, Eli Lilly

signed an agreement to payroyalties to the University toincrease production

• First bottles contained U-10insulin

• 3 to 5 cc were injected at atime

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Plasmids• Small supplemental circles of DNA

• 5000 - 20,000 base pairs• self-replicating

• carry extra genes• 2-30 genes• genes for antibiotic resistance

• can be exchanged between bacteria• bacterial sex!!• rapid evolution

• can be imported fromenvironment

Grow bacteria…make more

growbacteria

harvest (purify)protein

transformedbacteria

plasmid

gene fromother organism

+

recombinantplasmid

vector

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Human Bacterial Diseases• Tuberculosis

• aficts respiratory system and easily transmittedfrom person to person through the air

• Tooth decay• tooth decay caused by bacteria present in

plaque• high sugar diets increase tooth decay• lactic acid bacteria ferment sugars and reduce

pH, thus degenerating tooth enamel

Flesh-eating disease - Type I iscaused by anaerobic bacteria, withor without the presence of aerobicbacteria.

Pathogenicity

Endotoxin is a Lipid (not a protein) whichcauses host overreaction

Endotoxinsonly released when bacteria die and the cellwalls break down

Endotoxin is produced by Gram-negative bacteria

Pathogenicity

Examples include Neurotoxins andEnterotoxins

Exotoxins typically protein toxins

Exotoxin produced by Gram-positive bacteria

(not always true)

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Endospores Bacillus anthracis! The function of bacterial

endospores is survivalunder harshenvironmental conditions,not reproduction.

! They may remaindormant for long periods.

! TEM X41,000.

The BigPicture

Accumulation of O2 inatmosphere

Oldest Prokaryotic Fossils

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Do BacteriaCommunicateWith EachOther?

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Hawaiian Bobtailed SquidEuprymna scolopes

Light OrganContaining Vibrio fischeri

Bacterial Communication

producer Receptor

Auto-induction in Vibrio Fischeri

receptor producer

luxC luxD luxA luxB luxE

Genes for light

Autoinducer

Archaea

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Archaea

Thermophilesprokaryotes that live atvery high temperatures

Halophilesprokaryotes that live atvery high concentrationsof salt (NaCl)

Methanogensprokaryotes that producemethane

Methanogens

Methanogens

obligate anaerobes(free oxygen killsthem) cannot tolerateeven brief exposureto oxygen

produce methane(CH4) as a wasteproduct duringcellular respiration.

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Extreme Halophiles• Found in extremely saline or salty

environments as the Dead Sea, the GreatSalt Lake and evaporating ponds ofseawater where the salt concentration isvery high (as high as 25% NaCl).

• Also found in highly salted foods such assalted sh.

Thermophiles

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Comparisons… Comparing Prokaryotic and Eukaryotic Cells

Prokaryotes Eukaryotes

Have cell wallor membrane

Have DNA

Have cytoplasm

Have Organelles

Have anucleus

Have membranessurroundingorganelles

Are mostly bacteria Include allplant andanimal cells