Chapter 23: Bacteria

Overview on Bacteria -Microscopic -Unicellular organism -Prokaryote: –lack of membrane bound nucleus and organelles –found everywhere –harmful and beneficial types of bacteria –believed to have existed 3.5 billion years ago

Classification Bacteria are classified based upon the following characteristics: structure, physiology, molecular composition and reaction to staining. Two kingdoms…new version = Domains! 1. Archae -ancient, living in extreme environments -not commonly exposed to humans 2. Eubacteria - “bacteria” and germs -commonly exposed to humans

Domain: Archae Characteristics: Unusual lipid cell membrane Introns in their DNA No Peptidoglycan * Lives in extreme environments rRNA is similar to rRNA in eukaryotes genes are similar to eukaryotes Peptidoglycan: protein carbohydrate found in cell walls Archaeal Groups: 1) Methanogens 2) Halophiles 3) Thermoacidophiles

Methanogens Harvest energy by converting H 2 and CO 2 into methane gas. Anaerobic environments Facilitate fermentation Location: –Intestinal tracks, MARSH GAS, swamps and sewage

Extreme Halophiles Found in salty environments Use salt to generate ATP Thermoacidophiles Found in acidic and high temperature environments pH less than 2 Temp: up to 230 o F

Domain: Bacteria Characteristics: normal lipids in cell membrane no introns have peptidoglycan live in a variety of environments rRNA is different than rRNA of eukaryotes genes are not like genes of eukaryotes

Eubacteria Streptococci = chain of cocci Staphylococci = cluster of cocci

Gram Staining Gram Positive Thick layer of peptidoglycan in cell wall. Cause: retains purple stain. Gram Negative Thin cell wall (very small layer of peptidoglycan). Cause: unable to retain stain and appears pink.

Cell Membrane

Phylum Cyanobacteria: –Blue- green algae –gram – –Photosynthetic: capture sunlight to harvest energy Spirochetes: –Syphilis (STD and parasite) –Gram - Gram positive Bacteria: –Found in soil and used to produce antibiotics Proteobacteria: –Largest, most diverse –gram – –Heterotrophic, chemoautotrophic, nitrogen fixing

Structure

Structures Cell wall -Peptidoglycan - Antibiotics (resistance) Cytoplasm -DNA, ribosomes, membrane for cell respiration Capsule and Pili - protective outer covering -Glycocalyx: sticky covering used for attachment - Pili: hair-like protein structures used for attachment.

Structures Endospore - Dormant - Protects DNA during harsh conditions (chemicals, radiations, temperature changes) - Bacillus and Clostridium Movement -Flagellum - Rotating (spiral-shaped bacteria) - Slime (myxobacteria)

Nutrition and Growth Autotrophs Photoautotrophs: use sunlight as an energy source Chemoautrophs Heterotrophs Saprophytes : feed on dead organic matter ANAEROBE = NO O 2 AEROBES = YES O 2 Obligate Anaerobe (C. tetani) Facultative Anaerobe (E. coli) Obligate Aerobe (M. tuberculosis)

Reproduction and Recombination Transformation - Bacterial cells take DNA from an outside source and substitute for a similar DNA fragment in the chromosome of the cell. Conjugation - Two bacteria bind together and transfer genetic material to one another. - Conjugation Bridge: passageway used to transfer genetic material -Plasmids Transduction - a virus obtains a fragment of DNA from a bacterium. Replication of the virus results in new bacterium.

Pathology The study of disease Exotoxins : protein toxins –Gram positive bacteria ex: Tetanus Endotoxins : lipid and carbohydrate toxins –Gram negative bacteria –Released when bacteria die –Symptoms: fever, body aches and weakness ex: E. coli What can we do to avoid diseases caused by bacteria?

Name that pathogen!

Streptococcus mutans

Borrelia burgdorferi

Streptococcus pyogenes

Heliobacter pylori

Neisseria meningitidis

Antibiotics Gram Positive Antibiotics Penicillin: inhibits cell wall synthesis Cephalosporin Sulfa-drugs (synthetic): inhibits cell metabolism Ex: bacterial meningitis Broad Spectrum/ Gram Negative Antibiotics Tetracycline: Inhibits protein synthesis. Ex: skin infections (acne) and Lyme disease Ampicilin: Inhibits cell- wall synthesis Zithromax (Z Pack): inhibits protein synthesis

Benefits of Bacteria Healthy flora (E. coli) in the intestinal track Ex: Enteric Bacteria Lactobacillus found in sour dough bread. (Fermentation) Acidophilus Probiotics A mouse?