NASA has identified a new microbe present on Mars and requests that you determin
ID: 51901 • Letter: N
Question
NASA has identified a new microbe present on Mars and requests that you determine the genetic code of this organism. To accomplish this goal, you isolate an extract from this microbe that contains all the components necessary for protein synthesis except mRNA. Synthetic mRNAs are added to this extract and the resulting polypeptides are analyzed: From these data, what specifics can you conclude about the microbes genetic code? What is the sequence of the anticodon loop of a tRNA carrying a threonine? If you found that this microbe contained 61 different tRNAs, what could you speculate about the fidelity of translation n this organism?Explanation / Answer
The data specifies that the microbe's genetic code can be drawn from a polypeptide containing repeated nucleotides such as A and C.
The codon ACA codes for threonine and the anticodon loop of t- RNA contains UGU (that encodes cysteine).
Normally 32 tRNAs are atl east required to identify and pair with all 64 codons available in the cells. This means some tRNAs recognize more than one codon). But it was reported that some cells use more than 32 tRNAs. The microbe from mass contains 61 different tRNAs corresponding to all 64 codons. Once the tRNA encounters one of the 3 stop codons still another 3 codons leftout from the polypeptide. Almost 20 different aminoacyl tRNA synthetases occur in a cell that can specifically bind to an amino acid. Hence the translation can be carried out efficiently.
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