Horizontal Gene Transfer & Microbial Interactions Flashcards
segments of DNA that encode enzymes and other proteins that mediate the movement of DNA within genomes (intracellular mobility) or between cells (intercellular mobility)
Mobile genetic elements (MGEs)
genes common to all individuals of a species
Core genome
genes sporadically present in a species that may also be shared with other species
Pan genome
2 requirements of transformation
Competence
Host homologous recombination system
Does this describe generalized or specialized transduction:
Occasionally during lysis bacteriophage make a mistake and package host DNA in the capsid instead of bacteriophage DNA
This DNA is then carried passively with the phage head and injected into the next host cell it contacts
Each fragment of host DNA has an equal probability of being packaged
Generalized
Does this describe generalized or specialized transduction:
Generally involves close association between a phage and its host genome in the form of lysogeny
Chromosomal genes closely linked to the prophage may be erroneously packaged with the phage
These genes may become permanent residents within the phage genome leading to lysogenic converting phage
Specialized
Does this describe generalized or specialized transduction:
Homologous recombination is required to integrate the DNA into the recipient genome
Generalized
Does this describe generalized or specialized transduction:
Homologous recombination is not required because the DNA is part of the phage
Specialized
Broadest host range form of gene transfer
Conjugation
Does conjugation require recombination?
Generally does not
the most important mechanism of gene transfer in nature
Conjugation
Genetic elements that are replicated and inherited independently from the bacterial chromosome
Encode a negative regulator circuit (cop) that keeps the copy number within prescribed limits differentiating them from phage
Frequently carry genes for antibiotic resistance and virulence factors
Plasmids
non-replicating genetic elements capable of “hopping” or transposing from one position on the genome to another
Encode an enzyme called transposase that recognizes the ends, cuts them from their initial location and catalyze their movement to a new location
Transposons
clusters of related genes variably present in strains of the same species and associated with bacteriophage-like genes and properties
Have GC contents suggestive of foreign acquisition
Genomic (pathogenicity) islands
F plasmid sometimes integrates into the bacterial chromosome by homologous recombination, generating this type of cell
Hfr cell
An incorrect excision of the integrated F plasmid brings along a portion of the chromosome, generating this type of cell
F’
mobile genetic elements that combine features of bacteriophage, plasmids, and transposons and may include genomic islands
Integrative conjugative elements (ICE)
Colonizers are predominately
Anaerobic
Particularly in the GI
Microbial density and diversity increases or decreases from proximal to distal gut?
Increases
Microbial density and diversity increases or decreases from gut surface to lumen?
Increases
Simple sugars are taken up or digest here
Small intestine
Complex “indigestible” carbohydrates (fiber) are fermented by bacteria here
Large intestine
Does the small intestine have more or less sIgA than the colon?
More
Intestinal bacteria can synthesize these 2 vitamins
K and B vitamins
Intestinal bacteria can synthesize short chain fatty acids (SCFA), particularly this
Butyrate
Capsular polysaccharides and SCFAs stimulate production of these two things
IL-10 and Tregs