Probiotics Exam 3 Questions With Complete Solutions What is the microbiota? - Correct Answers ✅The microorganisms that live in an established environment What is the microbiome? - Correct Answers ✅The full complement of microbes, their genes, and genomes in a particular environment The gut microbiota is a complex community of microbes- estimated to contain 200 trillion cells and - Correct Answers ✅> 1000 diverse microbial species 10 x the number of human cells in our body Gut microbiome is 150 x larger than the human genome The microbiota is ___% of total body mass and generally _____
- Correct Answers ✅1-3%, non-pathogenic (human
microbial cells outnumber host cells 10x) Animals, including humans are usually ___ in utero - Correct Answers ✅germfree When do microorganisms begin colonization in and on the surface of the body? - Correct Answers ✅soon after birth What is normal microbiota? - Correct Answers ✅microorganisms that establish permanent colonies inside or on the body without producing disease 1 / 4
Probiotics Exam 3 Questions With Complete Solutions What are examples of normal microbiota? - Correct Answers ✅Staphylococcus on epidermis and mucus membranes; Escherichia coli in colon What is transient microbiota? - Correct Answers ✅are 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 human body do not allow them to become permanent.What is the relationship between the normal microbiota and
the host? - Correct Answers ✅Symbiosis (living together):
long-term interaction between two or more different biological species What are the three types of symbiosis with the host and normal microbiota with examples? - Correct Answers
✅Mutualism: both organisms benefit (E. coli in colon
synthesize vitamin K)
Parasitism: one organism benefits at the expense of the other
(disease causing bacteria)
Commensalism: one organism benefits, and the other is
unaffected (mycobacteria in the ear) 2 / 4
Probiotics Exam 3 Questions With Complete Solutions What are opportunistic pathogens? - Correct Answers ✅Opportunistic pathogens do not cause disease under normal conditions (live in their normal habitat) but cause disease under special conditions.What are two opportunistic pathogens? - Correct Answers ✅Streptococcus pneumoniae and E. coli The host and microbes have a mutualistic relationship (beneficial to both).. - Correct Answers ✅Fundamental role
in the immune maturation of the host: The complete absence
bacteria in the gut (gnotic mouse models) results in defective gut associated/mesenteric lymphoid tissue, low Ievels IgA -Immune balance with host
-specific functions of the microbiota: seal body spaces,
mitigate intestinal pathogens, signaling, metabolic end products What are the methods to study microbiota? - Correct Answers ✅-16S-based approach -Shotgun metagenomic approach How is 16s rRNA gene sequencing used? - Correct Answers ✅-16S rRNA gene present in all Bacteria and Archaea -Gene contains highly conserved and more variable regions 3 / 4
Probiotics Exam 3 Questions With Complete Solutions -amplify 16S rRNA genes using primers directed at conserved regions but flanking variable regions -align gene sequences, resolve phylogenetic relationships at different depths What are operational taxonomic units? - Correct Answers ✅An operational taxonomic unit (OTU) is 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 (approximately 97% similarity) -16S rRNA What are the limitations of 16S rRNA gene based analysis? - Correct Answers ✅-Many genomes have nearly identical copies -Not always possible to normalize 16S data -Cannot always obtain accurate estimates of diversity and abundance -Strains of same species can have different phenotypes & functional capabilities -Strain-level resolution not always possible -Conservation of 16S gene sequence can mask sequence diversity in rest of genome
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