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