Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

What is the primary role of mRNA?

1. To assemble ribosomes

2. To carry amino acids

3. To serve as a template for protein synthesis

4. To stabilize DNA structure

The correct answer is: To serve as a template for protein synthesis

The primary role of mRNA, or messenger RNA, is to serve as a template for protein synthesis. During the process of transcription, DNA is transcribed into mRNA, which carries the encoded information from the DNA out of the nucleus and into the cytoplasm. Here, the mRNA interacts with ribosomes, the cellular structures where proteins are synthesized. The ribosomes read the sequence of codons in the mRNA, which specifies the order in which amino acids should be linked together to form a protein. This process is known as translation, and it is essential for cellular function and the expression of genes. The other roles mentioned do not accurately describe the function of mRNA. For instance, while ribosomes are crucial for protein synthesis, they are not assembled by mRNA. Instead, ribosomal RNA (rRNA) and proteins make up the ribosomes. The transportation of amino acids is managed by transfer RNA (tRNA), which brings specific amino acids to the ribosome according to the sequence dictated by the mRNA. Finally, stabilizing DNA structure is a function associated with proteins called histones and other structural components, rather than mRNA. Therefore, the correct understanding of mRNA's role underscores its importance in the central dogma of