Lecture 1: The Microbrial World Flashcards
What are microbes?
Microbes are organism (microorganism) that exist as single cell or cell clusters and are too small to be seen with naked eye
What are the 3 domains of the phylogenetic Tree of Life?
Bacteria Eukarya: animals, Fungi, plants, Protists Archaea
What are the classification of microorganisms based on?
Alignment and comparison of 16SrRNA genes of all organisms
Why are most organisms harmless and play an essential role in our life and environment?
Microbes are at the base of food chain in oceans, lakes, rivers and soil Microbes participate in photosynthesis which generate food and oxygen Microbes break down waste (sewage treatment) Detoxify pollutants (oil, mercury)
What does microbiota present at each body site affect?
Numerous biological functions important for maintaining health (development of Immune system)
What is symbiosis?
Long-term interaction between two or more different biological species
What is commensalism?
One organism benefits and the other is unaffected e.g. Streptococcus (in mouth)
What is mutualism?
Both organism benefit e.g. E.coli in colon synthesise vitamin K
What is parasitism?
One organism benefits at the expense of other e.g. bacteria causing disease -pathogens
What is a microbial pathogen?
A microbe able to induce disease, an infection, in given host
What is primary pathogen?
Cause disease when there is an infection, not normally associated with host
What is an example of primary pathogen?
E.g. Vibrio cholerae , mycobacterium tuberculosis
What is an example of opportunistic pathogen?
Only cause disease in compromised host, sometimes part of normal flora
What is an example of opportunistic pathogen?
Pseudomonas, Candida
What is an infection?
Multiplication of a bacterial pathogen within host
What is pathogenicity?
The ability of microbe to cause disease
What is virulence?
The quantitative ability of microbe to cause disease
What is virulence determined by?
Characteristic of the organism
What is Lethal dose 50: LD50?
Dose of organism that kills 50% of the host in the test group (experimental studies)