Bacterial Morphology & Physiology Flashcards

Question

What are bacterial biofilms?

Answer 1

* The formation of a slime layer is indicative of biofilm formation * The majority of bacterial infections treated by clinicians involve biofilms * Pseudomonas aeruginosa infections in cystic fibrosis patients * Staphylococcus epidermidis catheter related infections

Answer 2

Bacteria divide by Binary Fission - Binary Fission - Chromosome divides to produce two identical copies - These copies segregate to opposite ends of the cell - Cell wall is laid down the middle of the cell to ultimately produce two new cells which are identical

Answer 3

Bacterial growth proceeds exponentially • Generation times can be as fast as 20 minutes • Contributes to the remarkable adaptability of bacteria Growth in a hostile environment can create a selective pressure for mutant cells which can persist. One mutant cell which can survive will rapidly grow and take over.

Answer 4

``` 1. Lag Phase • Adaptation 2. Logarithmic Phase • Cells multiply at the maximum rate 3. Stationary Phase • Lack of nutrients and buildup of toxic metabolic intermediates means multiplication is balanced by cell death 4. Phase of decline ```

Answer 5

For Bacterial Cells to Grow they require: 1. energy 2. the building blocks required for the construction of cellular machinery and 3. appropriate environmental conditions

Answer 6

Nutrient Requirements • Water • Carbon (carbohydrate) • Nitrogen (protein) • Inorganic salts • Iron –sequestered by siderophores (= Siderophores are small, high-affinity iron-chelating compounds secreted by microorganisms such as bacteria and fungi and serving to transport iron across cell membranes) • Oxidation of organic compounds (carbohydrates, lipids, proteins)

Answer 7

* The ability of individual bacterial species to produce their own cellular components will dictate its nutritional requirements * E.g. some species can synthesis all essential amino acids whereas others need amino acids to be added to their growth media (auxotrophs).

Answer 8

* Derived from the enzymatic breakdown of organic substrates (carbohydrates, lipids or proteins) in a process called Catabolism * Energy generated from catabolism is used to synthesise cellular constituents in a process called anabolism

Answer 9

Catabolism + Anabolism = Metabolism

Answer 10

``` Bacterial Energy Production ATP synthesis required for: • Metabolic Processes • Flagellum Movement • Nutrient Transport ```

Answer 11

* Electrons passing through ETC’s provides energy to move protons outside the cytoplasmic membrane * Creates proton gradient * Protons return to cytoplasm through special proton channels to balance the gradient generating energy for ATP synthesis

Answer 12

Obligate anaerobes are sensitive to superoxide radicals -lack Superoxide dismutase (important antioxidant defence against oxidative stress in the body) • Alternative electron acceptors are used instead of oxygen (eg NO2) • Different cytochrome electron transport chains are employed

Answer 13

* Cytochrome electron transfer pathways not involved * Organic acids used as terminal electron acceptors * Products include ethanol, acetic acid and butyric acid

Answer 14

* Different genera of bacteria can be differentiated from one another on the basis of their cell shape, how they are arranged when viewed by microscopy and Gram stain result * Gram-positive and Gram-negative bacteria differ from another in the structure of their cell envelope (cell envelope = cytoplasmic membrane, cell wall (thicker in Gram-positives) and outer membrane (only in Gram-negatives) * Bacteria can possess pilli to aid in attachment, flagellae for movement, some can produce spores for survival and most can produce a biofilm. All important factors in pathogenesis of infection and for treatment * Bacterial cells can multiply rapidly, utilise different nutrients and pathways for energy (ATP) production and some can vary their oxygen requirements during respiration