CHAPTER 19 NOTES BACTERIA

CHARACTERISTICS OF BACTERIA Prokaryotic or Eukaryotic: Prokaryotic Unicellular or Multicellular: Unicellular Autotroph or Heterotroph: Autotrophs and Heterotrophs Which Kingdom do they belong in? Eubacteria & Archaebacteria Examples: bacteria, methanogens & halophiles, cyanobacteria (autotroph)

TYPICAL BACTERIUM CELL MEMBRANE CYTOPLASM FLAGELLA DNA CELL WALL PILI

Most Bacteria reproduce by one of 3 means: 1. Asexually Also known as binary fission in which the chromosome replicates and then the cell divides This produces 2 identical cells 2. Sexually Also known as conjugation in which genetic material is exchanged through cell-to-cell contact This increases the genetic diversity of bacteria

Most Bacteria reproduce by one of 3 means: 3. Spore Formation When living conditions become unfavorable, some bacteria can form dehydrated cells known as endospores Endospores have thick walls and can resist heat, drought and radiation and thus they can survive harsh conditions When conditions improve, the spore will germinate and bacteria will grow again

HOW ARE BACTERIA CLASSIFIED?

Bacteria are divided into 2 main groups: 1. Archaebacteria Found living in harsh environments, like hot springs, near undersea volcanic vents and in highly salty water These bacteria are further divided based on the environments in which they live 2. Eubacteria Include all the organisms commonly called bacteria Live in much less harsh environments

Bacteria can also be classified by their shape: 1. Cocci Sphere-shaped 2. Bacilli Rod-shaped 3. Spirilla Spiral-shaped

Bacteria can be classified by their cell wall differences: The technique to see these differences is called GRAM STAINING 1. Gram-positive (looks purple) 2. Gram-negative (looks red)

Other ways to identify Bacteria By their Nutrition 1. Autotroph Ex. Cyanobacteria 2. Heterotrophs Ex. Bacteria Based on Respiration 1. Aerobes- need oxygen during respiration 2. Anaerobes – do not use oxygen during respiration

IMPORTANCE OF BACTERIA

ECOLOGICAL ROLES 1. Bacteria act as decomposers, which means they break down dead organic materials 2. They also help recycle carbon, nitrogen and sulfur and other chemicals needed by living things 3. Many bacteria live with organisms of other species in a relationship called symbiosis bacteria in your mouth (bacteria benefit & you are harmed) bacteria in cow intestines (bacteria benefit & cow benefits) E. coli, a bacteria found in human intestines, helps with the process of digestion

DISEASES CAUSED BY BACTERIA Some bacteria cause diseases in humans Some examples are: Tuberculosis, anthrax, lyme disease, strep throat, cholera Antibiotics can kill harmful bacteria if used properly

HUMAN USES OF BACTERIA Bioremediation – use of microorganisms to help restore natural environmental conditions; ex. Sewage treatment plants Bacteria are used in the production of many foods; some examples are: cheese, yogurt, vinegar, beverages Bacteria have applications in medicine; some bacteria have been genetically engineered to produce insulin