Question

13) Which nucleotide monomer is REPLACED by the nucleotide URACIL (U) when a gene (DNA) is converted to an mRNA during the process of transcription?

A) Adenine B) Guanine C) Cytosine D) Thymine

14) Different RNA molecules have diverse roles in cell biology; for example- mRNAs are the substrates for protein synthesis, which is performed by a large enzyme complex called the ribosome- a cellular machine composed of proteins and:

A) siRNA B) rRNA C) tRNA D) All of these

15) The ribosome will convert an mRNA molecule into a polypeptide protein during a reaction called:

A) Polymerization B) Transcription C) Translation D) Nucleation

16) Proteins are produced as the ribosome “reads” through an mRNA molecule based on small sequences that occur in groups of 3 nucleotides called:

A) Codons B) Exons C) Amino Acids D) Genes

Answer 1

Answer 13. The nucleotides are monomer units of nucleic acids (DNA and RNA). The genetic information is stored in the form of base sequences. It is nucleotide thymine (T) which is replaced by uracil (U) when a gene (DNA) is converted to an mRNA during the process of transcription. Therefore, option "D" Thymine is the correct answer.

The nucleotides adenine, guanine, and cytosine is not the right answer as these nucleotides are not replaced by any other nucleotide during the transcription process.

Answer 14. The genetic information stored in the DNA is transferred to mRNA and then expressed in the form of proteins by a process known as translation (protein synthesis). Translation takes place in ribosomes. The ribosomes are tiny structures present in the cell and composed of proteins and ribosomal RNA (rRNA). Therefore option "B" rRNA is the right answer.

The siRNA is small interfering RNA which is a component of RNA interference and regulates the gene expression. Therefore, siRNA is not the right answer. The tRNA is transfer RNA which mediates the transfer of amino acids to the translation site. These are part of translation process but not the ribosomes, therefore, tRNA is not the right answer.

Answer 15. The ribosome will convert an mRNA molecule into a polypeptide protein during a reaction called translation. So, option "C" translation is the right answer.

The polymerization is a general term used for the chemical process of joining monomer units together. The polypeptide is also a result of polymerization of amino acids but the term translation is more specific. Therefore, polymerization is not the right answer. Transcription is the process through which RNA is synthesized from DNA. Therefore, transcription is not the right answer. Nucleation is a process to determine the formation of a newly organized structure and therefore, nucleation is not the right answer.

Answer 16. Proteins are produced as the ribosome reads through an mRNA based on small sequences that occur in groups of 3 nucleotides called a codon. The codons are nucleotide triplets that code for amino acids. Therefore, option "A" codons is the right answer.

Exons are the coding region of the mRNA which codes for proteins therefore, the exon is not the right answer. Amino acids are the organic molecules which are monomer units of proteins. They either synthesized in the body or consumed through foods. Therefore, the amino acid is not the right answer. Genes are the nucleotide sequences that code for RNA and protein. The genetic information is stored in these sequences and transferred to future generations and therefore, the gene is not the correct answer.