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Bacteria
Characteristics of Bacteria.• Smallest and simplest living thing• Have no organelles, including no nucleus• Genetic material = simple circular chromosome• They have cell walls to protect them from outside pressure• Transmitted through:
– air– Water– Human
Contact– Contaminated
Food
Bacterial Shape & Arrangement
SHAPES:• Coccus: round• Bacillus: rod
shaped• Spirillum: spirals
ARRANGEMENTS:• Diplo: pairs• Staphylo: clusters• Strepto: chains
Types of MetabolismObligate aerobes: • require oxygen to live• Example: E.coli lives in mammal intestinesObligate ananaerobes: • Killed in the
presence of oxygen
• Example: SyphillisFacultative aerobes: • can live with or
w/o oxygen
Bacterial Adaptations for Survival.
ENDOSPORES:• Hard, outer covering
produced during harsh environments
• Resistant to: – drying out– boiling
• Metabolism slows down inside endospore
• Resumes growing when conditions are more favorable
Endospore
TOXIN PRODUCTION:• Some bacteria
produce poisons when the Endospore begins to grow
• Toxins kill off other bacteria – providing more food
for the surviving bacteria
• Some toxins are deadly
• Examples: – Botulism (food
poisoning)– Tetanus (lock jaw)
Alexander Fleming
• Alexander Fleming -was a Scottish biologist and pharmacologist. He wrote many articles on bacteriology, immunology, and chemotherapy. His best-known discoveries are the enzyme lysozyme in 1923 and the antibiotic substance penicillin from the mould Penicillium notatum in 1928, for which he shared the Nobel Prize in Physiology or Medicine in 1945
Penicillin
• It was a discovery that would change the course of history. The active ingredient in that mould, which Fleming named penicillin, turned out to be an infection-fighting agent of enormous potency. When it was finally recognized for what it was, the most efficacious life-saving drug in the world, penicillin would alter forever the treatment of bacterial infections.
Bacterial ReproductionBINARY FISSION:• Asexually Reproduction
• Splitting in ½ after copying the DNA• Occurs very quickly• Will stop reproducing only if:
– Run out of food– Dry up– Poisoned by own wastes
CONJUGATION:• Sexual Reproduction • Transfers all or part of the DNA between 2 bacteria• Transfer through a projection called a Pilli• Occurs when threatened, • Hope to pass on
genetic material – Will make the
bacteria resistant to changes.
Immune Response in Humans.• I.S. fights off
invaders which are called ANTIGENS
• Our bodies produce ANTIBODIES against each antigen
• Antibodies lock on to the pathogen’s active site or prevent its attachment
Types of immunity• Resistance to DiseasePassive Immunity: • Antibodies are:
– Acquired– Passed from mother to
child– Injected
Active Immunity: • Exposure to antigen:
– Recovery of disease– Through vaccination
Vaccination: • Injection of:
– Weakened Antigen– Pieces of antigens
Bacterial UsesFOOD FLAVORINGS:• Food flavors are produced
by:– Fermentation– Bacterial wastes, etc.
• EX: Vinegar, yogurt, butter, cheese, pickles, buttermilk, sauerkraut
ANTIBIOTIC PRODUCTION:• Some bacteria produce
antibiotics that will kill other forms of bacteria
• Antibiotics kill bacteria only!
Nitrogen Fixation
• The process by which free nitrogen from the air is combined with other elements to form inorganic compounds, such as ammonium ions, which can then be converted by nitrification into nutrients that can be readily absorbed by plants and other organisms for incorporation into more complex organic compounds.
Nitrogen Fixation
• Many species of cyanobacteria and certain other forms of bacteria, especially those that live in the roots of legumes, conduct nitrogen fixation as part of their metabolism, using the enzyme nitrogenase to combine nitrogen with hydrogen as ammonia. All living organisms are dependent on nitrogen fixation and would ultimately die without