Question

Which is soluble RNA?
A. HnRNA
B. rRNA
C. mRNA
D. tRNA

Answer 1

Hint: It plays a role in protein synthesis by decoding a specific codon of mRNA, using its anticodon, in order to transfer a specific amino acid to the end of a chain in the ribosome. It is the smallest RNA that takes part in protein synthesis.

Complete Answer:
RNA or ribonucleic acid is a polymer of nucleotides which is made up of a ribose sugar, a phosphate, and bases such as adenine, cytosine, guanine, and uracil. There are different types of RNA. The main three types of RNA are mRNA, tRNA, and rRNA.

1) hnRNA stands for heterogeneous nuclear RNA. It refers to the large pre-mRNAs of different nucleotide sequences formed by RNA Polymerase II and transformed into cytoplasmic mRNAs inside the nucleus.

2) rRNA directs the translation of mRNA into proteins. There are two main components of ribosomes- the small ribosomal subunits that read the RNA, and the large subunits that join amino acids to form a polypeptide chain. Each subunit contains one or more molecules of ribosomal RNA (rRNA) and various ribosomal proteins (r-protein or rProteins).

3) mRNA transcribes the DNA genetic code into a form that can be read and used for making protein. The genetic information from the nucleus into a cell's cytoplasm is carried by mRNA.

4) tRNAs are an important element in translation whose primary function is the transfer of amino acids during protein synthesis. So they are called transfer RNAs. tRNA is soluble in 1 M NaCl. Each amino acid has its own form of tRNA that binds it and transports it to the growing end of a polypeptide chain when needed by the next word code on mRNA. At each step, the right tRNA with its attached amino acid is selected as each particular tRNA molecule contains three-base sequences that can form base-pair with its complementary code word in the mRNA.

So, the correct answer is option D, i.e., tRNA.

Note: tRNA makes up about 15 percent of the overall RNA in the cell. Transfer RNA molecules have a particular stem loop shape allowing them to act as adapter molecules that bring activated amino acids to the ribosome machinery.