Prokaryotes And The Origins of Metabolic Diversity Kingdom Monera.

Prokaryotes And The Origins of Metabolic Diversity

Kingdom Monera

The Oldest Organisms

• Oldest fossils go back 3.5 bya

• Chemical cycles evolved in prokaryotes

• Wide range of modes of nutrition

• Est. diversity of up to 4 million species

• Two main brances are archaea and bacteria

The Three Domains

Comparing DomainsCHARACTERISTICS BACTERIA ARCHAEA EUKARYA

Peptidoglycan in cell wall

Present Absent Absent

RNA Polymerase One kind only Several kinds Several kinds

Initiator amino acid in protein synthesis

Formyl-methionine Methionine Methionine

Histones associated with DNA

None Present Present

Introns in genes None Some Present

Three Common ShapesSpheres - Cocci Rods - Bacilli

Helices – Spirilla, spirochetes

Classification By Gram Stain

Gram Positive and Gram Negative Bacteria

Pilli

• Allow bacteria to attach to a substrate

• Allow for exchange of plasmids during conjugation

• Not present in all bacterial groups

Some Bacteria Are Motile

• Bacilli may move using one or more flagella

• Narrower than eukaryotic flagella

• Lack membrane covering

• Not a 9+2 pattern• Exhibit taxis: chemo or

photo

Flagella

Reproduction and Genetic Recombination

• Asexual reproduction by binary fission – 20min. in log phase growth

• Three mechanisms of genetic recombination:

1. transformation2. conjugation3. transduction

• Mutation is the major source of genetic variation

Bacilli Produce Endospores

• Bacillus anthracis• Resistant capsule• Survives many

attempts destroy it• Requires sterilization

with heat and pressure:

• Steam at 15 lbs. per sq. in. for at least 20 min.

Nutrition and Metabolic DiversityMode of Nutrition Energy

SourceCarbon Source

Type of Organism

Photoautotrophs Sunlight CO2 Cyanobacteria, certain protists (algae)

Chemoautotrophs Inorganic Chemicals

(H2S, NH3, Fe2+)

CO2 Sulfur bacteria

Photoheterotrophs Sunlight Organic molecules

Certain prokaryotes

Chemoheterotrophs Organic molecules

Organic molecules

Animals, fungi, many protists, prokaryotes, parasitic plants

Evolution of Photosynthesis

Archaea

• Methanogens – use CO2 to oxidize H2 into CH4

• Exteme halophiles: (Bacteriorhodopsin is their photosynthetic pigment. Purple color)

• Extreme thermophiles: Oxidize sulfur for energy at deep-sea thermal vents at 105ºC

Ecological Impact of Prokaryotes

• Decomposers: Recycle chemical elements between biological and physical components of the ecosystem

• Fix carbon (as CO2) and nitrogen (as NH3)

• Produce O2 (cyanobacteria)

• Symbiotic:

mutualism – cyanobacteria in root nodules

commensalism – bacteria in/on the body

parasitism – pathogenic bacteria• Streptomyces – Source of our antibiotics

Koch’s Postulates

1. Find the same pathogen in each diseased individual.

2. Isolate pathogen from diseased individual and grow it in pure culture.

3. Induce disease using pure culture.4. Re-isolate pathogen from individuals in which

disease was induced from pure culture.** Doesn’t work for all pathogens (Treponema

pallidum, the cause of syphilis, can’t be cultured on media)

Exotoxins

• Proteins secreted by prokaryotes• Clostridium botulinum – botulism (botox)• Vibrio cholerae – Cholera (severe diarrhea)• E. coli – Traveller’s diarrhea

Endotoxins

• Components of the outer membranes of certain gram-negative bacteria

• Genus Salmonella – Causes food poisoning• Actinomycetes – Fungus-like prokaryotes

1. Mycobacterium sp. (Tuberculosis & leprosy)

2. Streptomyces sp. (Antibiotics)

Benefit to Society

• Remove pollutants from soil, water, or air

• Oil spills

• Sewage treatment

• Production of drugs by genetic engineering

• Prevention of freeze damage to crops

• Antibiotic production