9. The Human Microbiome Flashcards
Why are bacteria important?
- affect environment
- health and disease
- biotechnology
Efforts to sequence human genome began in …
1990
The first microbial genome was sequenced in … and it was of …
- 1995
- haemophilus influenzae
Structure of an open reading frame
- one long coding sequence
- along it there is a ribosomal binding site, start codon and stop codon
How to find open reading frames
- computer finds possible start codons
- and possible stop codons
- computer counts codons between start and stop
- finds possible ribosomal binding sites
- calculates codon bias in ORF
- decides if ORF is likely to be genuine
- list of probable ORFs produced by computer
It is now routine to sequence a microbial genome. Who uses it? Why?
- Public Health England
- to identify and monitor infectious diseases
- can look at core set of genes and then dispensable ones
Define ‘pan/core concept’
genomes of bacterial species consist of two components
Define ‘core and pan genome’
- core is shared by all strains of species
- pan is is core including all optional extras present in some but not all strains of species
Define ‘chromosomal islands’
- region of bacterial chromosome of foreign origin
- contains clustered genes for some extra property such as virulence or symbiosis
Define ‘pathogenicity islands’
chromosomal islands containing genes for virulence
Why are chromosomal islands believed to be of foreign origin?
- extra regions often flanked by inverted repeats
- base composition and codon usage in chromosomal islands often differ from rest of genome
- often found in some strains of a species but not others
Human body has … cells
It’s colonised by … bacteria
Intestinal tract has a biomass of …
- 1 trillion
- 10 trillion bacteria
- 2kg
Define ‘genome’
total complement of genetic info of a cell or virus
Define ‘metagenome’
total genetic complement of all cells present in particular environment
Define ‘epigenome’
total number of possible epigenetic changes
