Short Notes For Neet Trna Structure
Transfer RNA (tRNA) is a type of RNA that helps to synthesize proteins from messenger RNA (mRNA). tRNA acts as an adapter molecule during the process of translation, and was formerly known as soluble RNA (sRNA). It functions as a bridge between amino acids and nucleic acids, carrying the amino acid to be incorporated into the peptide chain and deciphering the codon for the same in the mRNA molecule.
Let’s learn about its structure.
tRNA Structure
The tRNAs are generally between 76-90 nucleotides in length. Each amino acid has its own specific tRNA. Stop codons are not recognized by any tRNAs. The secondary structure of tRNA is in the form of a clover leaf, while its tertiary structure resembles an inverted ‘L’ shape. The folded structure is formed due to hydrogen bonding between complementary bases.
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Cloverleaf Structure of tRNA
The secondary folded structure of tRNA has the appearance of a three-leafed clover, due to its three hairpin loops. The main constituents of tRNA are:
Acceptor Arm
The base pairing of a 5’ terminal and 3’ terminal, consisting of 7-9 nucleotides, forms a specific sequence of CCA or CCA tail at the 3’ end. The 5’ terminal has a phosphate group, and an amino acid attaches to the 3’ hydroxyl group of the acceptor arm.
The aminoacylation of tRNA, or charging of tRNA, is the first step of the translation process. The enzyme aminoacyl tRNA synthetases catalyse the reaction.
DHU Loop
The stem of the D-arm is comprised of 3-4 base pairs, and it culminates in a loop known as the D-loop, which typically contains the modified nucleotide dihydrouridine.
Anticodon Loop
It has a 5 base pair long stem. It has an anticodon loop, which contains the complementary codon (3 nucleotides sequence) present on mRNA for the amino acid it carries. These unpaired bases of anticodon loop pair with the mRNA codon. Each codon is identified by a specific tRNA.
TΨC Loop
The T arm consists of a stem of 4-5 bp and a loop containing pseudouridine, modified uridine.
Variable Loop
The variable loop is present between the TΨC loop and the anticodon loop. Its size varies from 3-21 bases and helps in the recognition of the tRNA molecule.
Extended Reading: Difference between mRNA, tRNA and rRNA
tRNA Function
tRNA (transfer RNA) is a type of RNA molecule that helps decode genetic information stored in mRNA during protein synthesis. It carries amino acids to the ribosome, and it reads the codon of the mRNA and translates it into the appropriate amino acid.
tRNA plays an important role in protein synthesis.
It acts as an adapter molecule, connecting amino acids to their respective codon on mRNA.
Aminoacylation of tRNA is the first step in protein synthesis.
tRNA is specific to each amino acid and carries them during the translation process in the ribosomes’ subunits.
The tRNA transfers the amino acid to the growing polypeptide chain in the ribosomes, with three binding sites for tRNA - A (aminoacyl), P (peptidyl) and E (exit) - respectively.
The decoding of codons of mRNA by specific tRNAs continues until the entire sequence of a polypeptide chain is translated.
Check out these MCQs on structure of RNA!
Frequently Asked Questions
The function of tRNA is to translate the genetic code of mRNA into amino acids during protein synthesis.
tRNA acts as an adapter molecule, linking specific amino acids to their respective codons in the mRNA template. This helps in protein synthesis by decoding the mRNA sequence.
The primary difference between tRNA and mRNA is that tRNA carries amino acids to the ribosome to be used in the formation of proteins, while mRNA carries genetic information from the nucleus to the ribosome.
mRNA is a linear single-stranded structure that acts as a template for protein synthesis, whereas tRNA is a clover leaf shaped structure that transports specific amino acids to the ribosome for protein synthesis.
tRNA is located in the cytoplasm of the cell.
tRNA (transfer RNA) and rRNA (ribosomal RNA) are located in the cellular cytoplasm. Both are involved in the process of protein synthesis.
