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BACTERIA

BACTERIA. Structures in a Typical Bacteria. Flagella — long hairlike structures growing from a cell that aid in movement Chromosome — usually a single, circular piece of DNA Ribosome — used for making proteins Plasmid — small circular piece of DNA

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BACTERIA

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  1. BACTERIA

  2. Structures in a Typical Bacteria • Flagella—longhairlike structures growing from a cell that aid in movement • Chromosome—usuallya single, circular piece of DNA • Ribosome—usedfor making proteins • Plasmid—smallcircular piece of DNA • Cell membrane (a.k.a. plasma membrane)—separatesthe cell from its external environment • Pili—short, hairlike structures involved in reproduction and cell-to-cell contact • Cell wall—protects and support the cell • Capsule—located around the cell wall; bacteria with capsules are more likely to cause diseases

  3. Reproduction • Binary Fission: • Cell division in which the cell forms 2 identical cells • It is a form of asexual reproduction

  4. Reproduction (cont.) • Conjugation: • Process of exchanging genetic material though cell-to-cell contact; DNA and plasmids move through the pili from one bacterial cell to another • It is a form of sexual reproduction

  5. Classification of Bacteria • Cell Shape: • Spheres—cocci • Rods—bacilli • Spirals--spirilla • Respiration: • Aerobes—use oxygen • Anaerobes—do not use oxygen

  6. Classification of Bacteria (cont.) • Cell Wall Composition: • Gram positive • Gram negative • Nutrition: • Autotrophs • Heterotrophs—most bacteria are heterotrophic

  7. Endospores • Thick walled structures that can resist heat, drought, and radiation • Bacterial cells can form endospores when living conditions become unfavorable

  8. Transformation • Picking up and incorporating DNA from dead bacterial cells

  9. Roles of Bacteria in the Biosphere • Decomposers: break down organic materials • Bioremediation: bacteria are used to rid the environment of harmful substances (i.e. oil spills) • Manufacturing: bacteria are used to ferment sugar to make cheese, yogurt and some beverages

  10. Roles of Bacteria in the Biosphere (cont.) • Medicine: bacteria are used to make human proteins such as insulin • Nitrogen fixation: provides usable nitrogen for plants; ex: bacteria that live on roots of legumes • Symbiosis: relationship between 2 organisms in which at least one of the partners benefits; ex: bacteria found in the intestines of mammals help with digestion and provide vitamins

  11. Pathogens • Bacteria that cause diseases are called pathogens • Some pathogens use the body’s cells as food; ex: mycobacterium tuberculosis • Other pathogens release toxins that can travel throughout the body; ex: streptococcus

  12. Vaccines • An injection of dead bacteria or virus will stimulate the immune system to make antibodies • The antibodies will provide immunity against the disease

  13. Antibiotics • Antibiotics can work to block bacterial cell growth and reproduction • Some antibiotics, like penicillin, attack the cell wall of the bacterial cells • Penicillin makes holes in the wall causing water to rush into the cell and rupturing it

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