Probiotics MCB6424 Exam 3
Questions With Correct Solutions
/.microbiota vs microbiome - Answer-✅microbiota - organisms
microbiome - organisms + genes + genome
/.The gut microbiota contains more than __ cells
more than __ species - Answer-✅200 trillion cells
>1000 species
/.The microbiome contains __x the cells in the human body
The gut microbiome is __x larger than the human genome - Answer-✅10x cells
150x genome
/.Who came up with the official definition of microbiota? - Answer-✅Lederberg and
McCray, 2001
/.Microbiota definition - Answer-✅"Ecological community of commensal, symbiotic, and
pathogenic microorganisms within a body space or other environment"
/.True/False the microbiome is generally non-pathogenic and beneficial to the host -
Answer-✅true
/.Transient microbiota - Answer-✅microbes that are present for various periods and
then disappear
Although these types of organisms may colonize a host and reproduce briefly, the
defenses of the body do not allow them to become permanent.
/.3 types of Symbiosis - Answer-✅mutualism, commensalism, parasitism
/.Commensalism - Answer-✅one organism benefits the other and the other is
unaffected (ex: mycobacteria in the ear)
/.mutualism - Answer-✅both organisms benefit (ex: E. coli in the colon, synthesizes vit
K)
/.parasitism - Answer-✅one benefits at the expense of the other (ex: disease causing
bacteria)
, /.___ plays a fundamental role in immune maturation - complete absence of bacteria in
the gut results in ___ and low levels of ____ - Answer-✅mutualism
results in gut-associated mesenteric lymph tissue
low levels IgA
/.Specific functions of the microbiota - Answer-✅seal body spaces, mitigate intestinal
pathogens, maintain tissue homeostasis, facilitate fermentation of dietary fiber (pectin,
etc), critical energy yield, metabolic end products and therapeutic drug processing,
signaling among cells and organ systems (butyrate - energy for gut epithelial cells;
acetate and propionate - lipogenesis and
/.methods to study the microbiota - Answer-✅16S rRNA gene sequencing-based
surveys and shotgun metagenomic approach
/.16S rRNA gene sequencing-based surveys - Answer-✅Gene contains highly
conserved regions and variable regions
amplify 16S rRNA genes using primers directed at conserved regions but flanking
variable regions
align gene sequences, resolve phylogenetic relationships at different depths
/.Most 16S rRNA sequences come from previously ____ - Answer-✅undescribed
microbes
/.Operational Taxonomic Units - Answer-✅a definition used to classify groups of closely
related individuals
Sequences are clustered according to their similarity to one another
OTUs are defined based on the similarity threshold (about 97% similarity)
/.limitations of 16S rRNA gene based analysis - Answer-✅Many genomes have miltuple
and nearly-identical copies of the 16S rRNA operons
Not always possible to accurately normalize 16S data
Cannot always obtain accurate estimates of diversity and abundance
Strain-level resolution of the microbial community is not always possible
Strains of the same species can have different phenotypes and functional capabilities
not possible to accurately infer or reconstruct functional and metabolic capabilities
conservation of 16S genome sequence can mask sequence diversity in rest of the
genome
/.Metagenomics - Answer-✅predictions of function based on gene content
/.Phyla in microbiome - Answer-✅firmicutes (>250 genera)
bacteroidetes
actinobacteria
Questions With Correct Solutions
/.microbiota vs microbiome - Answer-✅microbiota - organisms
microbiome - organisms + genes + genome
/.The gut microbiota contains more than __ cells
more than __ species - Answer-✅200 trillion cells
>1000 species
/.The microbiome contains __x the cells in the human body
The gut microbiome is __x larger than the human genome - Answer-✅10x cells
150x genome
/.Who came up with the official definition of microbiota? - Answer-✅Lederberg and
McCray, 2001
/.Microbiota definition - Answer-✅"Ecological community of commensal, symbiotic, and
pathogenic microorganisms within a body space or other environment"
/.True/False the microbiome is generally non-pathogenic and beneficial to the host -
Answer-✅true
/.Transient microbiota - Answer-✅microbes that are present for various periods and
then disappear
Although these types of organisms may colonize a host and reproduce briefly, the
defenses of the body do not allow them to become permanent.
/.3 types of Symbiosis - Answer-✅mutualism, commensalism, parasitism
/.Commensalism - Answer-✅one organism benefits the other and the other is
unaffected (ex: mycobacteria in the ear)
/.mutualism - Answer-✅both organisms benefit (ex: E. coli in the colon, synthesizes vit
K)
/.parasitism - Answer-✅one benefits at the expense of the other (ex: disease causing
bacteria)
, /.___ plays a fundamental role in immune maturation - complete absence of bacteria in
the gut results in ___ and low levels of ____ - Answer-✅mutualism
results in gut-associated mesenteric lymph tissue
low levels IgA
/.Specific functions of the microbiota - Answer-✅seal body spaces, mitigate intestinal
pathogens, maintain tissue homeostasis, facilitate fermentation of dietary fiber (pectin,
etc), critical energy yield, metabolic end products and therapeutic drug processing,
signaling among cells and organ systems (butyrate - energy for gut epithelial cells;
acetate and propionate - lipogenesis and
/.methods to study the microbiota - Answer-✅16S rRNA gene sequencing-based
surveys and shotgun metagenomic approach
/.16S rRNA gene sequencing-based surveys - Answer-✅Gene contains highly
conserved regions and variable regions
amplify 16S rRNA genes using primers directed at conserved regions but flanking
variable regions
align gene sequences, resolve phylogenetic relationships at different depths
/.Most 16S rRNA sequences come from previously ____ - Answer-✅undescribed
microbes
/.Operational Taxonomic Units - Answer-✅a definition used to classify groups of closely
related individuals
Sequences are clustered according to their similarity to one another
OTUs are defined based on the similarity threshold (about 97% similarity)
/.limitations of 16S rRNA gene based analysis - Answer-✅Many genomes have miltuple
and nearly-identical copies of the 16S rRNA operons
Not always possible to accurately normalize 16S data
Cannot always obtain accurate estimates of diversity and abundance
Strain-level resolution of the microbial community is not always possible
Strains of the same species can have different phenotypes and functional capabilities
not possible to accurately infer or reconstruct functional and metabolic capabilities
conservation of 16S genome sequence can mask sequence diversity in rest of the
genome
/.Metagenomics - Answer-✅predictions of function based on gene content
/.Phyla in microbiome - Answer-✅firmicutes (>250 genera)
bacteroidetes
actinobacteria
