Question

Non-genetic RNA is of:
a) Two types b) three types c) four types d) one type

Answer 1

Hint : RNA is a nucleic acid found in both nucleus and cytoplasm. RNA is of two types- genetic and non-genetic RNA.

Stepwise answer: To answer this question, we must understand the structure and types of RNA.
Generally RNA is a single stranded structure and it is chemically a polynucleotide molecule. The nitrogen bases in RNA are: Uracil, Cytosine, Adenine and Guanine. (Thymine is not present). In an RNA molecule, base pairing is not fixed and definite. Therefore, purine : pyrimidine ratio may or may not be 1:1.
Types of RNA: Genetic RNA acts as genetic material of some viruses. Non-genetic RNA is of three types: m- RNA, t-RNA and r-RNA.
m-RNA is also known as messenger RNA. It is simple and straight without any fold. It makes up 3-5% of total cellular RNA.
Function: it carries coded information about the sequence of amino acids in the polypeptide chain, from DNA to ribosomes, during protein synthesis.
r-RNA: Ribosomal RNA is a single stranded structure which is variously folded upon itself. In folded regions it may show pairing between complementary bases. It makes up 80% of cellular RNA. It remains associated with ribosomes permanently.
Function: It provides proper binding sites for m-RNA. It orients m-RNA molecules in such a way that all the codons are properly read.
t-RNA: Transfer RNA is also single stranded. It makes up about 10-20% of cellular RNA. It is the smallest type of RNA. It shows two patterns of folding upon itself. The structure of t-RNA can be explained using two models: the Hair pin model (proposed by Hoagland) and the Clover leaf model (proposed by Holley).
Function: It carries specific types of amino acids at CCA end to ribosome during protein synthesis. It places required amino acids properly in sequence and translates the coded message of m-RNA in terms of amino acid.

Thus, the correct answer is option B- three types.

Note : The three types of non-genetic RNA play an important role in protein synthesis in both prokaryotic and eukaryotic cells. All these types help in the process of transcription and translation.