Codons are triplets of nucleotides that together specify an amino acid residue in a polypeptide chain. Most organisms use 20 or 21 amino acids to make their polypeptides, which are proteins or protein precursors. Because there are four possible nucleotides, adenine (A), guanine (G), cytosine (C) and thymine (T) in DNA, a triplet has the potential to distinguish between 64 amino acids. Due to this redundancy, many amino acids can be coded by more than one triplet. Organisms often show strong preference for one of the several codons that all encode the same given amino acid. Such preference may arise if the transfer RNA (tRNA) corresponding to the preferred codon translates faster than the alternative codons. In this scenario, the preferred codon would become more common in the genome and hence the concentration of preferred-codon tRNAs would be rate limiting. It would then be efficient for the preferred tRNA to be present at a higher concentration, and the less preferred tRNAs at a lesser concentration, reinforcing the preference for the preferred codon.
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calls say I'll be out until six o'clock."
"Yes, my Lady." Parkins knew on which side his bread was buttered.
like his former mistress, Lady Colchester, that he sometimes
her waiting carriage.
CHAPTER VI
approached. Quarter of nine found him leaning over the banisters
rails watching the top of every head that crossed the spacious
guest, fearing some of the girls, many of whom had already
flash of a bald head, glistening in the glare of the lower hall
arrived, and on the very minute. Parkins's special instructions,
was wonderful what an impressive note was in the boy.html">boy's voice when
hat, overshoes (if he wore any), umbrella.html">umbrella and all, and the four
flunky, and two firm and decided, as befitted a grenadier crossing
overjoyed boy--"'way up near the sky. One flight less than my own.
worry, only Anno Domini--you'll come to it some day. How
his coat; Parkins, with his nose in the air (he had heard his
and the umbrella in the corner.
"Where will you sit--in the big chair by the fire or in this long
of a man was the things he lived with. "Ah! books?" and he peered
very good--why, certainly it is--Where did you get this Morland?"
bedroom--yes, and the bath. Very charming, I must say. You.
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