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)

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

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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.

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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!