Chapter 13: Prokaryotes and Viruses

Prokaryotes Oldest organisms on Earth The most dominant and successful forms of life Great metabolic diversity and rapid rate of growth Escherichia coli double in size every 20 min.

Prokaryotes Occur in icy areas of Antarctica Dark depths of the ocean Near-boiling waters of hot springs Can survive without free oxygen

What is the basic structure of a prokaryotic cell? Lack an organized nucleus Plasma membrane and cell wall Nucleiod region- Singular circular or continuous DNA molecule (non-histone protien) May contain smaller extrachromosomal pies of circular DNA – plasmids Ribosomes and inclusions Cynobacteria is an exception contains many thylakoids (structure found in chloroplast responsible for photosynthesis)

Three major forms of prokaryotes Bacilli- rod shaped bacterium Cocci- sphere shape Spirilla- long curved or spiral rods

A filamentous actinomycete Streptomyces scabies Bacterium found in soil causes potato scab disease

Prokaryotes cause disease Both animal and plants Humans (TB, cholera, anthrax, gonorrhea, botulism, syphilis, tetanus, ulcers)

Bacterial effects on Plants

Flagella on Pseudomonas marginalis- soil bacterium Causes soft rot disease found in fleshy vegetables

Bacillus-Clostridium botulinum- deadly food poisoning

Bacillus can form Endospores Certain species of Bacteria (Bacillus and Clostridium) can form endospores Endospores- dormant bacterial cells when food supply is low, resist heat, radiation, chemicals, Protoplast is dehydrated Can remain viable for many years Viable endospore obtained from a million year old Extinct Bee gut Mature Endospore- Bacillus Megaterium

Cocci- Micrococcus luteus- and others that cause Milk to sour and oxidizes ammonia to nitrites

Fruiting body of myxobacterium (Chrondomyces crocatus) A gliding bacterium produces fruiting Bodies, each containing 1 million Cells (Slime Bacteria). Another form of Bacteria- Slime Bacteria

Slime bacteria - Psuedonomonas Pseudomonas corrugata Pith Necrosis of Tomato

Binary fission Cell division in a bacterium Mutation does occur and are responsible for evolutionary adaptability

Pilus Donor cell Recipient cell

Metabolic Diversity Some Prokaryotes are autotrophs- self feeding –Photosythetic Sunlight (Energy)+ 6CO2 + 6H2O C6H12O6 + 6O2 –Chemosythetic (chemolithotroph) 6{CO2}+6{H2O}+3{H2S} C6H12O6+3{H2SO4}

Beggiatoa gigantea sewage Filamentous sulfur oxidizing bacteria

Spiroplasmas- motile bacteria that cause corn stunt disease And stubborn disease

Mycoplasmiclike organism devestated a grove of Coconut palms

Mycoplasmalike Organisms- slow weakening

General life cycle of a virus Two stages 1. Replication inside host 2. Spread to new host

Tobacco Mosaic Virus

Streaked flowers of Rembrandt tulips Viral infection eventually weakens plant

Wound tumor virus Tumor produced in sweet clover

Electron Microscope Tumor virus particles

Prokaryotes world ecosystem Fixing nitrogen- incorporating nitrogen gas into nitrogen compounds Autotrophic bacteria major contributor to global carbon balance (more than 90% other than that associated with human activity comes from bacteria and fungi) Decomposers (natural and toxins)- patroleum, pesticides, mercury, and dyes-

Cyanobacteria Important in Carbon and nitrogen cycles Photosynthetic cyanobacteria have chlorophyll a, carotenoids and phycobilins. Important lineage of bacteria and eukaryotic cells Limestone

Cyanobacteria electron micrograph

Cyanobacteria Genera Oscillatoria

Cyanobacteria Genera Nostoc commune

Plankton Cells of cyanobacteria living in freshwater or marine habitats Plankton commonly contain bright irregularly shaped structures – gas vesicles Gas vesicles provide bouancy When not able to regulate they float and form mass “blooms” Red sea- Trichodesmium

Nitrogen fixation Some cyanobacteria can fix nitrogen converting nitrogen gas to ammonium A form which the nitrogen is available for biological reactions Occurs in Heterocyst-specialized enlarged cells

Filament of anabaena Heterocyst

Filament of Anabaena with heterocyst

Rice Planting Malaysia- Anabaena allow for continuous Growing w/o fertilizer