Humber Admissions Practice Test

What role does mRNA play in the process of protein synthesis?

1. Decodes DNA

2. Transports amino acids

3. Specifies the amino acid sequence

4. Inhibits protein synthesis

The correct answer is: Specifies the amino acid sequence

mRNA, or messenger RNA, is crucial in the process of protein synthesis as it carries the genetic information from DNA to the ribosome, where proteins are synthesized. The primary role of mRNA is to specify the amino acid sequence of the protein being produced. It is transcribed from the DNA and serves as a template during translation, where the ribosome reads the sequence of nucleotides in the mRNA to assemble the corresponding amino acids in the correct order. This process ensures the synthesis of proteins that match the genetic instructions provided by the organism's DNA. The other options do not reflect the correct role of mRNA: while mRNA relates to the decoding of DNA, it does not directly perform this task; rather, it is synthesized based on DNA. mRNA also does not transport amino acids; that function is performed by transfer RNA (tRNA), which brings the appropriate amino acids to the ribosome. Inhibiting protein synthesis is a role played by certain molecules, such as inhibitors or regulatory factors, not by mRNA in its function. Thus, specifying the amino acid sequence is the defining and correct function of mRNA in the protein synthesis process.