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