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Bacteria Discussion

Bacteria Discussion. September 7, 2012 (Really). Basic Characteristics Single celled No membrane-bound organelles Nucleoid region Microscopic. I. Prokaryotes. B. How do we identify different types of prokaryotes?. Identified by the following: Shapes

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Bacteria Discussion

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  1. Bacteria Discussion September 7, 2012 (Really)

  2. Basic Characteristics Single celled No membrane-bound organelles Nucleoid region Microscopic I. Prokaryotes

  3. B. How do we identify different types of prokaryotes? • Identified by the following: • Shapes • Chemical nature of their cell walls • The ways they move • The ways they obtain energy

  4. Cell wall – protects the cell & gives it shape. Outer membrane – protects the cell against some antibiotics (only present in some) C. Basic Structure

  5. C. Basic Structure (cont.) • Cell membrane – regulates movement of materials into & out of the cell; contains enzymes important to cellular respiration. • Plasmid – circular piece of DNA that contains some genes obtained through genetic recombination. • Capsule & Slime layer – protect the cell & assist in attaching the cell to other surfaces.

  6. Bacillus Coccus Spirilla 3 basic shapes

  7. • Cell Arrangements – Diplo – cells are paired – Staphylo – cells are in grape-like clusters – Strepto – cells are in long chains

  8. II. Shapes & Groupings of bacteria Three basic shapes of bacteria Bacillus = rod shape Coccus = round or spherical shape Spirilla = spiral shape

  9. B. Cell Groupings • Diplo – cells are paired • Staphylo – cells are in grape-like clusters • Strepto – cells are in long chains

  10. III. Cell wall types • Two different types of cell walls are found in eubacteria • Bacteria cells containing peptidoglycan • Bacteria with an outer layer of lipid and carbohydrate molecules • Gram staining helps to tell them apart using two different types of dye • Violet - primary stain • Red - counterstain

  11. IV. Growth & Reproduction • Binary Fission: bacterium doubles in size, it replicates its DNA and divides in half • Each daughter cell is a clone of the parent • Is this sexual or asexual reproduction? • Asexual

  12. IV. Growth & Reproduction (cont.) • Types of Genetic Recombination • Conjugation: process by which two living bacteria bind together and one bacterium transfers genetic information to the other • Transformation: occurs when bacterium binds to and then takes up DNA released by dead bacteria • Transduction: viruses carry portions of DNA from one bacterium to another

  13. IV. Growth & Reproduction (cont.) • Endospore: thick-walled, dehydrated structures inside bacterium • Protects the cell against harsh environmental conditions, such as heat and drought • May allow the bacterium to survive for thousands of years • Not for reproduction, but for survival

  14. V. Examples of Bacteria • Bacillus cereus • Found in soil • Straight rods • Arranged singly or in pairs • Cause of a lot of food borne illnesses

  15. V. Examples (cont.) • Aquaspirillumserpens • Found in fresh water • Spiral shaped • Arranged singly

  16. V. Examples (cont.) • Escherichia coli (E. Coli) • Straight rods • Arranged singly or in pairs • Named after pediatrician who discovered it • Digest food in your intestines (benefit to us) • Some strains are very harmful and can lead to food borne illnesses

  17. V. Examples (cont.) • Staphylococcus epidermidis • Epidermis = skin • Spherical shape • In clusters • Usually not pathogenic • Staphylococcus aureus • Spherical shape • In clusters • Most common type of staph infections in humans • MRSA: Methicillin-resistant S. aureus • Highly resistant to antibiotics

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