Chapter 16 The Origin and Evolution of Microbial Life: Prokaryotes and Protists

Prokaryotes Streptococcus pneumoniaeChlamydia

More Prokaryotes Dental PlagueStrep Throat

2 main prokaryote Domains BacteriaArchea

Shapes of Prokaryotes Cocci: can occur in chains-streptococci; can occur in cluster- staphylococcus Bacilli: most occur singly-species shown here is found in fertile soil Spirochete: virbrios, spirilla, spirochetes- example: syphillis

Cell Wall of Prokaryotes Wall maintains cell shape, provides physical protection and prevents cell from bursting in a hypotonic solution Capsule-a sticky layer of polysaccharides that helps prokaryotes adhere to a substrate or colony

Pili Hair-like appendages used to stick one prokaryote to another or to surfaces Sex pili: bonds prokaryotes to each other during conjugation

Gram positive and Gram negative Gram negative is more threatening than gram positive because the outer membrane is often toxic so it fights against the body’s defense and resists antibiotics

Motility Flagella In prokaryotes the flagella is a naked protein with no microtubules. It is attached by a system of rotating rings anchored to the cell membrane and cell wall

flagella

Reproduction and Adaptation Reproduce quickly through binary fission Bacillus anthracis- form specialized cells when the environment become inhospitable for the bacteria to live. The specialized cells are called endospores

Internal Organization Simpler than eukaryotes Can contain infoldings in their plasma membranes for aerobic respiration or thylakoid membranes for photosynthesis Plasmids Small ribosomes See figure 323

Prokaryotic nutrition Source of energy – phototrophs (use the sun) – Chemotrophs (use the energy stored in organic or inorganic molecules)

Modes of Nutrition Photoautotrophs (cyanobacteria) Photoheterotrophs (purple nonsulfur bacteria) Chemoautotrophs (sulfur bacteria in deep sea vents) Chemoheterotophs (most diverse group)

Biofilms A surface of one or many species of bacteria Common in dental plaque, urinary tract infections, aquatic habitats,

Archaea and Extreme environments Extreme Halophile – Salt lovers – Thrive in very salty environments – San Francisco Bay The colors of the pond result from the dense growth of the Archaea that thrive when the salinity of the water reaches 15-20%

Extreme Thermophiles Heat lovers Thrive in very hot water, some in over 100 degrees Can live in hot acidic pools giving the pools a vivid greenish color

Methanogens Live in anaerobic environments Thrive in anaerobic mud bottoms of lakes and swamps Live in the digestive tracts of humans causing gas

Domain Bacteria Proteobacteria – Live in nodules of legumes – Can be used by scientist to carry foreign genomes of crop plants – Includes salmonella, cholera, E.coli

Cholera An infection in the small intestine that causes profuse watery diarrhia

Spirochetes Helical bacteria Include anthrax, syphillis, lyme’s disease

Gram positive bacteria Actinomycetes: form branched chains of cells Streptomyces: use to make antibiotics

Cyanobacteria Plant-like oxygen generating photosynthesis Provide an enormous amount of food for freshwater and marine ecosystems

Disease Causing Bacteria Exotoxins – Proteins secreted by bacterial cells and powerful toxins Examples – Clostridium tetani –lock jaw – Staphylococcus aureus- can cause toxic shock syndrome or layers of skin to come off

Endotoxins Components of an outer membrane of a gram- negative bacteria that are released when a cell dies or is digested by a defensive cell Fever, aches, drop in blood pressure Bacterial meningitis, typhoid fever, food poisoning, lyme’s disease

Anthrax Found in the soil of agricultural regions Inhalation of anthrax is deadly

Bioremediation The use of organisms to remove pollutants from soil, air or water Prokaryotic decomposers are mainstays of sewage treatment facilities

Protists Diverse collection of mostly unicellular eukaryotes