Bacteria Outline Essay, Research Paper

Bacteria

- Oldest, structurally simplest, most abundant forms of life

- Only organism with prokaryotic cellular organization

- The only members of the kingdom Monera (4800 different kinds)

- Characteristics change depending on growth conditions

- Maintenance of life depends on them – play vital role of productivity and as decomposers

- Capable of fixing atmospheric N for use by other organisms

- Used in production and fermentation of various food and as antibiotics and is being tested for

insect control

- Prokaryotes vs. Eukaryotes

- Multi-cellularity

- All bacteria fundamentally single celled

- Sometimes cells adhere within a matrix to form filaments

- Activities of bacterial colonies less integrated and coordinated than in multicellular eukaryotes

Eukaryotes Bacteria

Cell Size 10x size of bacteria 1 micrometer (?m) diameter

Chromosomes Membrane bound nucleus w/ chromosomes w/ nucleic acid & proteins No nucleus/chromosomes w/ DNA

DNA contained in cytoplasm

Cell Division and Genetic Remcombination Mitosis involving microtubules

Sexual reproduction – meiosis/syngamy Binary fusion

Lack of sexual reproduction – no equal participation

Internal Compartementalization Respirational enzymes packed into mitochondria Corresponding enzymes bound to cell membranes

Cytoplasm – no internal compartments/organelles (except ribosomes)

No cytoskeleton

Flagella Complex 9+2 structure of microtubules (whip-like motion) Simple w/ a single fiber protein flagellin

Spins like a propellar

Autotrophic Diversity Enzymes for photosyn. Packed in membrane-bound organelles (plastids)

Only 1 type of photo. – release of O2 Enzymes bound to cell membrane

Several patterns of aerobic/anaerobic photo. w/ formation of S, O, sulfate

Chemosynthesis – process where certain bacteria obtain energy from oxidation of inorganic compounds and obtain C from CO2

- Bacterial Structure

- Lypopolysaccharide – polysaccharide chain with lipids attached

- Molecules of it deposited over layer of gram positive – forming outer membrane

- Makes gram negative bacteria resistant to many antibiotics to which gram positive bacteria are susceptible

- Capsule – gelatinous layer surrounding cell

- Bacilli – straight, rod-shaped bacteria

- Cocci – spherical bacteria

- Spirilla – spirally coiled bacteria

- Spores – single-celled bodies that grow into new bacterial individuals

- Some bacteria change into stalked structures, grow long, branched filaments or form erect structures that release spores

- Bacterial cells have simple structures

- 2 kinds of cell walls – gram negative/positive

- Cytoplasm of a bacterium contain no internal compartments/organelles & is bound by a membrane encased w/i a cell wall composed of 1/more polysaccharides

- Pili – other kinds of hairlike outgrowths that occur on some bacteria cells – shorter than flagella

- Help bacterial cells to attach to appropriate substrates

- Endoscopes – resistant to environmental stress; may germinate & form new bacterial individuals after decades/centuries

- Bacterial Variation

- 2 processes lend variability to bacterial reproduction

- Mutation

- Because of the short generation time of bacteria whose populations often double in a few min., mutation plays important role in generating genetic diversity

- Genetic Recombination

- Transfer of genes from one cell to another as portions of viruses, plasmids, other DNA fragments

*Intestinal bacterium: typhoid, dysentry, other diseases

- Bacterial Ecology and Metabolic Diversity

- Bacteria most abundant organisms in most environments

- Obligate anaerobes – organisms cannot grow in presence of O2

- Facultative anaerobes – organisms that function as anaerobes/aerobes

- Aerobes – organisms that require O2

- Autotrophic bacteria

- Heterotrophs – get energy from organic material formed by other organisms (most bacteria)

- Autotrophs – obtain energy from nonorganic sources

- Photosynthetic bacteria – contain chlorophyll but not held in plastids

*Cyanobacteria, green/purple sulfur bacteria, purple nonsulfur bacteria

- Different colors caused by photosynthetic pigments

- Chemoautotrophic bacteria – derive energy from the oxidation of inorganic molecules (N, S, Fe compounds, gaseous H)

- Heterotrophic bacteria

- Saprobes – bacteria that obtain nourishment form dead organic material

- Autotrophic bacteria, capable of making their own food, obtain energy from light or the oxidation of inorganic molecules

- Heterotrophic bacteria obtain energy from breaking down organic compounds made by other organisms

- By-products of bacterial metabolism

- Antibiotics – valuable

- Botulism – food poisoning

- Salmonella – gastrointestinal disease

- N-fixing bacteria

- N fixation – carried out by nodule-forming bacteria

- Bacteria releases fixed N (when they break down proteins)

- N cycle carried out exclusively by bacteria

- Bacteria as plant pathogens

- Most plant diseases caused by bacteria

- Most bacteria that cause plant diseases are from a group of rod-shaped bacteria called pseudomonads

* Citrus canker (Florida) – destroy citrus seedlings

- Bacteria as human pathogens

- Cholera, leprosy, tetanus, bacterial pneumonia, whooping cough, diptheria

- Many diseases dispersed in food/water

- Legionnaires?s Disease

- Severe pneumonia – fatal in 15-20% of victims if untreated

- Caused by legionella – small, flagellated, rod-shaped, gram/-, bacteria w/ pointed ends

- Common in water

- Attacks monocytes (type of white blood cell)

- Destroyed with erythromycin treatment

- Sexually Transmitted Diseases

- Gonorrhea, syphilis – controlled w/ antibiotics (syphilis – penicillin)

- Infections caused by Chlamydia trachomatis (bacteria)

- Painful symptoms – causes sterility

- Controlled w/ antibiotic tetracycline

- Causes arthritis in young people

- Dental Caries (decay)

- Causes cavities in dental plaque (film on teeth)

- Plaque consists of bacteria cells surrounded by polysaccharide matrix

- Caused by diets high in sugar

- Prevented w/ antibiotics

- Bacterial Diversity

- Archaebacteria – distinctive membranes, unusual cell walls, unique metabolic cofactors

- Eubacteria – kingdom Archaebacteria belongs in

- Methanogenic – prominent Archaebacteria

- Produce methane from CO2 & H to obtain energy

- Source of marsh gas

- Reduce S to form hydrogen sulfide

- Archaebacteria ancient group of prokaryotes that are different from eubacteria – seem to be direct ancestors of eukaryotes

- Omnibacteria – rigid, rod-shaped, heterotrophic, gram/+

- Vibrios – comma-shaped that have single terminal flagellum

- Obligate parasites – organisms that can live only as parasites

- Rickettsias – bacteria causing Rocky Mountain spotted fever

- Cyanobacteria – photosynthetic bacteria – bring about increase of free O2 in the atmosphere (crucial for eukaryotic evolution)

- Produce accumulation of limestone deposits (stromatolites)

- Phycobilins – accessory pigments that are blue & red & water soluble

- Only in cyanobacteria, red algae, & cryptomonads

- Mucilaginous sheath that can be different colors (blooms in H2O)

- Fix atmospheric N in cells called heterocysts (especially important in rice fields)

- Chloroxybacteria – photosynthetic bacteria

- Fixes N

- Biochemical characteristics give rise to chloroplasts of green algae

- Mycoplasmas – Aphragmabacteria (phylum name)

- Cause diseases in mammals & birds

*Premature labor in women

*Pneumonia

- Treated with antibiotics

- Spiroplasmas – cause plant diseases

*Aster yellow

- Both (spiro-/myco- plasmas) lack cell walls & cells bounded by 3-layered lipid membrane

- Resistant to antibiotics & penicillin working to inhibit cell growth

- Spirochaetes – long spirilla where flagella are inserted beneath outer lipoprotein membrane of gram/- outer cell wall

- Agents of syphilis & yaws (disfiguring eye disease)

*Lyme disease (inflammatory ailment)- treated w/ penicillin/tetracycline

-Pseudomonads – straight/curved gram/- rods w/ 1/more flagella at one ent

- Soil/water – break down organic compounds (autotrophic)

- Plant pathogens – infections to people who eat the plants

-Actinomycetes – produce spores by division of terminal, erect branches into chains of small segments

- N fixing molecules formed at roots of flowering plants

- Dental plaque, leprosy, tuberculosis

- Ivermectin – antiparasitic agent, tetracycline, etc. made from actinomycetes

-Myxobacteria – gliding bacteria – unicellular rods

- Cells embedded in slimy polysaccharides they excrete

- Occur in soils – aerobes

- N Fixing Aerobic Bacteria – gram/- and flagellated

- Soil/water – converts N to a form which can be used by other organisms and itself

- Fermenting bacteria – obligate anaerobe – N fixing

-Chemoautotrophic bacteria

- Chemoautotrophy – metabolism that depends on chemical sources of energy like methane, ammonia, hydrogen sulfide

- Do not require sunlight

- Use N compounds to gain energy (Nitrosomonas)

- Oxidize inorganic S or Fe compounds to gain energy

- Use methane/methanol