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Introduction to Bacteria. Eukaryote:. Prokaryote:. (bacteria, that is!). What are bacteria?. Single celled organisms Very small Need a microscope to see Can be found on most materials and surfaces Billions on and in your body right now. E. Coli O157:H7 can make you very sick.
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Eukaryote: Prokaryote: (bacteria, that is!)
What are bacteria? Single celled organisms Very small Need a microscope to see Can be found on most materials and surfaces Billions on and in your body right now E. Coli O157:H7 can make you very sick. Streptococcus can cause strep throat. This E. coli helps you digest food.
What do they look like? Three basic shapes Rod shaped called bacilli (buh-sill-eye) Round shaped called cocci (cox-eye) Spiral shaped Some exist as single cells, others cluster together Bacilli Cocci Spiral Cluster of cocci
Characteristics of Bacteria Most have a cell wall Many have a capsule (jelly or slimy coating outside the cell wall, for protection) They have a single, circular chromosome. Some have plasmids (tiny rings of DNA separate from the chromosome.) Cytoplasmic Pili help them talk to other cells. Schraer, 632
Gram positive Gram negative Includes most of the pathogenic (disease-causing) bacteria
How do bacteria reproduce? Grow in number not in size Humans grow in size from child to adult Make copies of themselves by dividing in half Human parents create a child
Binary fission(for a quick clone) Normal bacterial reproduction: 1) chromosome replicates 2) copies separate as cell wall lengthens 3) cell membrane pinches in 4) septum/new wall grows 5) cells divide Bacillus dividing by fission SixKingdoms.html Steps in binary fission maricopa.edu
How Bacteria Populations Grow!! Growth Curve (in Culture) Schraer, 634
See Fission in Action Did you know?In ideal conditions, some species can divide every 10 MINUTES. What stops them? They run out of food or space, or wastes build up and poison them.
How do bacteria eat? Autotrophs: Some make their own food from sunlight—like plants (eg. cyanobacteria) Some make their own food from available chemicals (eg. methanogens) Heterotrophs: Some are scavengers --Share the environment around them Example: The bacteria in your stomach are now eating what you ate for breakfast Some are warriors --(pathogens) Attack other living things Example: The bacteria on your face can attack skin causing infection and acne Photosynthetic bacteria Harmless bacteria on the stomach lining E. Coli O157:H7 is a pathogen
A Closer Look – Helpful Bacteria www.bioweb.usu.edu Rhizobium spp. – fix nitrogen from the air and provide necessary nutrients for plants Pediococcus - used in production of fermented meats Eshchericia coli -- found in human intestines, produce vitamins and aid digestion. Leuconostoc cremoris – used in the production of buttermilk and sour cream Lactobacillus bulgaricus – used in the production of yogurt
What are some common pathogens? Pathogenic E. coli (like O157:H7) Found in contaminated meats, fruits and vegetables Salmonella Found in raw meats, poultry, eggs, sprouts, fruit and vegetables Listeria Found in deli foods, lunch meats, smoked fish and vegetables E. coli O157:H7 Salmonella Listeria
Nutrient agar is a general purpose prepared media (bacteria food!) and grows many types of bacteria and fungi. If you have a specific bacteria culture, you can spread the bacteria on the plate using a sterile swab or innoculating loop. The bacteria will grow and become visible in 24-48 hrs. … each colony represents one bacteria that was originally swabbed onto the plate. What should be true about all the bacteria in one colony?
