microbiology

• what is meant by the term microbiome?

  this is the accumulation of all the micro-organisms that live in an area, human microbiome is all the fungi, bacteria, viruses that live on and in the human body. aka normal flora
• what are the main groups of microbes?

  fungi, bacteria, viruses, protozoa
• explain in detail the differences between a prokaryote and a eukaryote?

  Prokaryote: No nucleus, no membrane-bound organelles. Eukaryote: Nucleus, membrane-bound organelles.
• define dimorphic?

  this is when something can exist in two distinct forms
• what is a prion?

  subviral entitiy composed of only a protein. it is a proteinaceous infectious particle which is acellular. capable of causing severe brain infections
• what makes a prion different to a virus?

  prions are smaller than viruses as they are just composed of a single protein, while a virus is composed of nucleic acids and a protein coat. proteins lack genes which is what distinguishes them from viruses
• name the 3 types of paracites

  1. protozoa
  2. helminths
  3. ectoparasites
• what is morphology and what is its use?

  the study of the shapes and arrangements of organims. Used to determine their function, development, and how evolution has effected them.
• name the 4 ways in which bacteria transfer genetic material

  1. transformation
  2. transduction
  3. conjugation
  4. transposition
• name 2 antibiotics that target cell wall synthesis

  penicillin and vancomycin
• mycology


  the study of fungi
• fungi


  eukaryotic organisms including yeasts, moulds, and mushrooms
• viruses


  non-cellular infectious agents consisting of genetic material enclosed in a protein coat
• what is morphology and what is its use?

  the study of shapes and arrangement of organisms. Used to determine their function, development, and how evolution has effected them
• Gram pos bacterial characteristics

  • thick layer of peptidoglycan
  • retains the crystal violet-iodine complex during gram-staining
  • appear purple under the microscope
• gram-neg features

  • thin cell wall with less layers of peptidoglycan
  • surrouneded by an outer membrane containing lipopolysaccharide
  • appear pink under the microscope
• what is meant by the term envelope?

  the envelope of a bacterial cell is the structural layer which encompasses all the membranes that protect the bacterial cell
• after completing the 4 step gram-staining, gram+ and gram- cells show different colours, why?


  gram+ retain the crystal violet-iodine complex due to their thick peptidoglycan layer, which allows them to appear purple

  gram- cells loose the crystal violet-iodine complex during the alcohol treatment (decolouriser) but pick up the counterstain (neutral red), which allows them to appear pink
• what bacteria cannot be stained using a gram stain, and what can be used instead?

  bacteria that lacks a cell wall (mycoplasma spp.) alternatives like the acid-fast stain may be used
• diplo


  pairs
• strepto


  chains
• staphylo


  clusters
• What is the function of the Flagella on the bacterial cell?

  Flagella: provide motility by rotating like propellers, allows bacteria to move from unfavourable conditions to more favourable ones
• what is the function of pili on the bacterial cell?

  attachment to surfaces or host cells, genetic exchange through conjugation, contribute to biofilm formation
• What is a chemoattractant?

  A chemical substance that attracts cells towards it

  Molecules released by cells to attract other cells
• what is a trichous


  structures on bacterial cells used for motility ex: flagella
• When are bacterial spores made?

  Spores are made when the bacterium is facing adverse conditions as a survival mechanism. By entering a dormant state they can withstand high temperatures, exposure to chemicals or radiation
• What is the benefit of a spore?

  Allows the bacteria to enter a protective dormant state so it can withstand adverse conditions
• What methods can be used to remove spores?

  Autoclaving

  Chemical sterilisation

  Irradiation with gamma rays
• Anthrax: bacillus anthracis
• Tetanus: clostridium tetani
• Botulism: clostridium botulinum
• Gas gangrene: clostridium perfringens
• What are the symptoms of anthrax?

  Fever, chills, difficulty breathing

  Death
• What are acid-fast bacteria?

  Group of bacteria characterised by their resistance to decolourisation by acid-alcohol solutions during staining procedures

  Due to presence of a waxy lipid layer in their cell walls
• Acid fast bacteria: mycobacteria spp.

  M tuberculosis
• What is aseptic technique?


  Set of practices and procedures used to prevent contamination of cultures, samples, or work surfaces by unwanted micro-organisms

  Maintaining a pathogen free environment
• What is laminar flow?

  Parallel movement of air, minimises the risk of airborne disease
• What are the 5 types of solid growth media?

  1. Nutrient Agar
  2. Selective Agar
  3. Differential Agar
  4. Enrichment Agar
  5. Specialised Agar
• What is spectrophotometry?


  Technique used to measure the concentration of a substance in a solution by analysing its absorption or transmission of light at specific wavelengths

  Commonly used to quantify the growth of bacterial cultures