Probiotics MCB6424 Exam 3 Questions With Complete Solutions

microbiota vs microbiome correct answer: microbiota - organisms microbiome - organisms + genes + genome The gut microbiota contains more than __ cells more than __ species correct 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 correct answer: 10x cells 150x genome Who came up with the official definition of microbiota? correct answer: Lederberg and McCray, 2001 Microbiota definition correct 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 correct answer: true Transient microbiota correct 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 correct answer: mutualism, commensalism, parasitism Commensalism correct answer: one organism benefits the other and the other is unaffected (ex: mycobacteria in the ear) mutualism correct answer: both organisms benefit (ex: E. coli in the colon, synthesizes vit K) parasitism correct 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 ____ correct answer: mutualism results in gut-associated mesenteric lymph tissue low levels IgA Specific functions of the microbiota correct 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 correct answer: 16S rRNA gene sequencing-based surveys and shotgun metagenomic approach 16S rRNA gene sequencing-based surveys correct 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 ____ correct answer: undescribed microbes Operational Taxonomic Units correct 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 correct 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 correct answer: predictions of function based on gene content