Microorganisms in the human colon are more often being described as mutualistic with human hosts rather than commensalistic. Why has this change in the definition of a symbiotic relationship occurred?
A. As we learn more about the ecology of the human microbiome, we have learned that these organisms are dependent on the nutrients that we provide for their survival.
B. As we learn more about the ecology of the human microbiome, we recognize our dependence on these organisms for immunity, vitamin production, and other essential processes.
C. As we learn more about the makeup of the human digestive tract, we realize that some microorganisms are potentially pathogenic while others are not.
D. All of the choices are correct.
Answer: B
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Poliovirus is an RNA virus of the picornavirus group, which uses its RNA as mRNA. At its end, the RNA genome has a viral protein (VPg) instead of a cap
This is followed by a nontranslated leader sequence, and then a single long protein-coding region (~7000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. What conclusion is most consistent with the results of the radioactive labeling experiment? A) Host cell ribosomes only translate the viral code into short polypeptides. B) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones. C) The RNA is translated into short polypeptides, which are subsequently assembled into large ones. D) The large radioactive polypeptides are coded by the host, whereas the short ones are coded for by the virus.
Domains of a protein can best be described as:
A. the unique sequences of each participating protomer. B. functional components of a protein. C. independently folding units of a polypeptide chain. D. None of the answers provided is correct. E. All of the answers provided are correct.
Neisseria gonorrhoeae may sometimes cause
A. ophthalmia neonatorum. B. salpingitis. C. lymphogranuloma venereum. D. nongonococcal urethritis. E. salpingitis and ophthalmia neonatorum.
How do steroid hormones differ from those derived from amino acids?
a. steroid hormones are not derived from organic molecules b. steroid hormones do not bind to plasma membrane receptors c. steroid hormones use a second messenger system
d. steroid hormones do not travel in the blood e. steroid hormones do not require receptors to function