Chapter 13, Problem 1MC

Summary Introduction

Introduction:

Ribonucleic acid is a polymer of nucleotides which is directed by the DNA for the synthesis of proteins. It is made up of ribose sugar and nitrogenous bases: adenine, guanine, cytosine, and uracil. RNA is structurally similar to DNA but differs on the basis of sugar, strand and nitrogen base.

Answer to Problem 1MC

Correct answer:

Messenger RNA carries the genetic information of DNA from the nucleus to cytoplasm for the protein synthesis. Therefore, option (b) is correct.

Option (b) is given as “messenger RNA”.

Explanation of Solution

Justify reason for the correct statement:

There are three classes of RNA: $\text{mRNA}$, $\text{tRNA}$ and $\text{rRNA}$. Messenger RNA $\left(\text{mRNA}\right)$ functions as an information carrier from DNA in nucleus to ribosome in cytoplasm of the cell. This information is used by the cell to direct the synthesis of proteins. Group of three bases in $\text{mRNA}$ is called as codons that specify which amino acid will be incorporated into a protein.

Hence, option (b) is correct.

Justify reasons for the incorrect statements:

Option (a) is given as “ribosomal RNA”.

Ribosomal RNA $\left(\text{rRNA}\right)$ and ribosomal proteins make ribosomes at which polypeptide chains are formed during translation. Hence, it is a wrong answer.

Option (c) is given as “transfer RNA”.

Transfer RNA $\left(\text{tRNA}\right)$ transfer the amino acid to the ribosomal unit in translation process by which the information in $\text{mRNA}$ is translated into protein molecules. Hence, it is a wrong answer.

Option (d) is given as “microRNA”

MicroRNA $\left(\text{miRNA}\right)$ is a class of noncoding RNA that is involved in the gene expression regulation during the post-transcriptional stage. Hence, it is a wrong answer.

Hence, options (a), (c), and (d) are incorrect.

Conclusion

The molecule that carries the genetic information for the protein synthesis from the nucleus to the cytoplasm is messenger RNA.