General Intro to Microbio/Microorganism, Struc & Func - S’s

• Define microbiology.

  Biology of organisms too small to be seen by the naked eye.
• Give four types of microbiomes.

  1. TSEs - Transmissible Spongiform Encephalopathies.
  2. Viruses.
  3. Bacteria.
  4. Eukaryotes - fungi and protozoa.
• What do TSEs do and give three examples.

  They cause sponge-like lesions in the brain.

  1. Kuru.
  2. Scrapie.
  3. Creutzfield-Jacob.
• What is the size order of bacteria, eukaryotes, and viruses?

  Biggest to smallest:

  1. Eukaryotes.
  2. Bacteria
  3. Viruses.
• How do bacteria and eukaryotes differ?

  Eukaryotes have organelles such as mitochondria within them (internal compartmentalisation).
• What five things make viruses differ from both bacteria and eukaryotes?

  1. Not visible in a light microscope - electron microscope required.
  2. Viruses cannot grow without a host.
  3. They cannot divide without a host.
  4. They are not metabolically active.
  5. They contain both DNA and RNA in their genome (bacteria and eukaryotes only have DNA).
• What are the two different types of protein coats a virus can have?

  1. Icosohedral - 20 faces.
  2. Helical.
• Give the steps in viral replication.

  1. Virus enters via receptors.
  2. Virus releases its genome.
  3. Virus replicates using host cell.
  4. Then uses reverse transcription to transcribe genome to produce viral proteins (capsid).
  5. The virus then leaves and infects other cells or becomes part of the host genome and is known as a pro-virus.
• How does bacteria replicate?

  Via binary fission.
• How is DNA stored in bacteria?

  In chromosomes and plasmids.
• How are proteins made in bacteria?

  mRNA enters the cell and associates with ribosomes to form proteins.
• When a bacteria is said in plural, what is the casing?

  Lower-case.
• Give six shapes/arrangements of bacteria.

  1. Bacilli - rod.
  2. Cocci - sphere.
  3. Spirochaetes - spiral.
  4. Curved (cholera) - curved.
  5. Streptococci - chains of spheres.
  6. Staphylcocci - bunches of spheres.
• What is the difference between gram + and gram - bacteria?

  They both have a capsule, peptidoglycan, and a cytoplasmic membrane.

  But gram - has LPS (lipopolysaccharides), outer membrane, lipoprotein, periplasmic space.
• What tinge does alpha haemolysis give and why?

  Green because of the breakdown of haemoglobin.
• What would you see after beta haemolysis?

  Clear zone around each colony.
• What is meant by typing?

  Defining the organism.
• How is serotyping carried out?

  Using antisera - determines which antigens are there.
• How is phage typing carried out?

  Using phage (bacterial viruses) that recognise surface proteins.
• How is genetic typing carried out?

  Using sequencing properties of DNA.
• Give four types of genetic typing.

  1. Plasmid profile.
  2. RFLF - restriction fragment length polymorphism.
  3. Probes.
  4. Polymerase chain reaction (PCR).
• What are three main differences between prokaryotic and eukaryotic cells?

  1. P - no internal membranes, E - DNA encased in nucleus.
  2. P - rigid cell wall, E - some have no cell wall (animals).
  3. P - 70s ribosomes, E - 80s ribosomes.
• What is the main difference between fungi and protozoa?

  Fungi is unicellular or multicellular.

  Protozoa is only unicellular.
• Give two types of fungi.

  1. Yeasts - grow unicellular and as hyphae, e.g. candida spp, cryptococcus spp.
  2. Moulds - grow as hyphae only, e.g. aspergillus spp, penicillium spp, fusarium spp.

  
• What does the fungal cell wall consist of?

  1. Manoproteins.
  2. B-glucan layer.
  3. Chitin layer.
  4. Cell membrane.
  5. Ergosterol within the cell membrane.
• What are bacteria that cause disease called?

  Pathogenic bacteria.
• What are ‘good’ bacteria known as?

  Commensals, normal flora.
• What are three things that can cause commensals to be disrupted?

  1. Antibiotics - can lead to salmonella and C. difficile.
  2. HIV - can lead to TB and Candida.
  3. Trauma - can lead to S. aureus entering the body via cuts.
• What are opportunistic bacteria called and how do they come about?

  Pathobionts, which occur through changes in the environment.
• Give two bacterias that have opposite reactions to two different organisms.

  1. Escherichia coli O157 - bad in humans, good in cattle.
  2. Salmonella typhimurium - bad in humans, good in chicken.