Transfer RNA
The transfer RNA is a kind of ribonucleic acid that is responsible for transporting the amino acids to the ribosomes where, according to the specified sequence in messenger RNA (transcribed, in turn, of the DNA) are proteins synthesized .
The RNA soluble or transfer (tRNA) represents approximately 15% of the entire RNA. It is made up of about 80 nucleotides, and is dispersed in the cell cytoplasm.
There is a tRNA molecule for each amino acid, with a specific triplet of nitrogenous bases, the anticodon, which varies between the different tRNAs.
The tRNA is single-stranded, but it presents areas of intra-strand complementarity, that is, complementary areas within the same chain, which causes them to pair, giving a characteristic structure similar to that of a three-leaf clover. In the secondary structure of tRNAs the following characteristics are distinguished:
- An arm called the D-arm and its handle. It is so named because it contains dihydrouridine.
- A T-arm (for carrying thymine) and its handle.
- An arm called the anticodon and its loop, complementary to the specific codon of the mRNA .
- An amino acid acceptor arm.
Although we speak of a cloverleaf-shaped structure, in reality, the tRNA molecule folds, acquiring a tertiary structure in the shape of an L.
In addition to the typical nucleotides of RNA, such as A, G, C and U, tRNA contains others that carry methylated bases, such as dihydrouridine (UH), ribothymidine (T), inosine (I), methylguanosine (GMe), etc., which constitute 10% of the total ribonucleotides of tRNA.
