I need a little more clarification on these two questions that aren\'t clearly a
ID: 67198 • Letter: I
Question
I need a little more clarification on these two questions that aren't clearly answered in my textbook or online. I have provided my answers thus far. Any help is appreciated to understand this better.
What evidence supports the hypothesis that peptide bond formation is catalyzed by a ribozyme?
The hypothesis that rRNA, and not a protein, is primarily responsible for both the structure and function the ribosome, is supported by ribosomal RNA being the main component of A sites, P sites and the interaction between the two ribosome sub-units where the polypeptide bonds are formed.
In an aminoacyl tRNA, why is the observed distance between the amino acid and the anticodon important?
Tertiary structure maintains the precise distance between the anticodon and amino acid. It is important for the recognition between the tRNA and the aminoacyl tRNA synthetase
Explanation / Answer
Attempts have been made to develop ribozymes as therapeutic agents, as enzymes which target defined RNA sequences for cleavage.
2)
The synthetase first binds ATP and the corresponding amino acid (or its precursor) to form an aminoacyl-adenylate, releasing inorganic pyrophosphate (PPi). The adenylate-aaRS complex then binds the appropriate tRNA molecule, and the amino acid is transferred from the aa-AMP to either the 2'- or the 3'-OH of the last tRNA nucleotide (A76) at the 3'-end.
The mechanism can be summarized in the following reaction series:
Summing the two reactions, the overall reaction is as following:
amino acid + tRNA + ATP aminoacyl-tRNA + AMP + PPi
The sum of these three reactions is highly exergonic, These 3 reactions can be combined to produce:
anti codon + tRNA + ATP + H20 anticodon -tRNA + AMP + 2PPi
Some synthetases also mediate a proofreading reaction to ensure high fidelity of tRNA charging; if the tRNA is found to be improperly charged, the aminoacyl-tRNA bond is hydrolyzed.
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