Introduction Flashcards
What is microbiota?
All microorganisms that reside inside the human body (90 trillion of bacteria, archaea, microeukaryotes and viruses)
What is the microbiome?
Microbes, their genes and gene products (RNA, proteins and metabolites)
Microbial genome exceeds human genome by at least 250 fold
Consequence of highly regulated host-microbial interactions
What are the types of microorganisms?
Commensals
Pathogens
Opportunistic pathogens
What are commensals?
Organisms that are a normal inhabitant of the human body
What are pathogens?
Organisms that are generally absent from healthy human microbiome but regularly causes disease in healthy humans
What are opportunistic pathogens?
Organisms widely distributed in healthy adults but can become invasive during immunosuppressive states
What is infectious disease?
The outcome of the method and site chosen by an organism for replication and persistence
Disease reflects the status of the host as much as it does the virulence characteristics of the causative organism
Name the groups of microorganisms
Bacteria Fungi Virus Prion Parasite
Describe bacteria
Cells are non-compartmentalised
DNA throughout cytoplasm as free-floating genetic material and plasmids
Survive in variety of environments
How do bacteria replicate?
Binary fission or spore formation
DNA replication, genome segregation, septum formation, division
What are the methods of horizontal gene transfer?
Transformation- by naked DNA/ plasmid transfer
Transduction- genes in bacterial viruses, phage
Conjugation- contact between cells
How do bacteria survive as endospores?
Found in some Gram-positive organisms (Bacillus and Clostridium)
Resistant to heat and drying- dormant
difficulty for sterilisation
What is a key molecule in bacterial cell walls?
Peptidoglycan
Makes bacterial cells rigid
Target for antibacterial drugs
Links/ peptide bridges support structure, NAM and NAG
