OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What is the first step in the process of making proteins using mRNA?

1. mRNA leaves the nucleus

2. The ribosome synthesizes the protein

3. DNA strands unzip and mRNA is made

4. Amino acids are matched to mRNA

The correct answer is: DNA strands unzip and mRNA is made

The first step in the process of making proteins using mRNA involves the transcription of DNA into mRNA, which occurs when the DNA strands unzip, allowing one strand to serve as a template for synthesizing a complementary mRNA strand. This process is crucial because it transforms the genetic information stored in DNA into a messenger format that can be understood by the ribosomes, the cellular machinery responsible for protein synthesis. By contrasting this with the other steps, it is clear that the roles of mRNA leaving the nucleus, the ribosome synthesizing the protein, and amino acids matching to mRNA all come after this initial transcription step. Once mRNA is produced, it exits the nucleus to participate in translation, where ribosomes read the mRNA sequence, and amino acids are brought in to form the protein based on the instructions carried by the mRNA. Thus, the correct answer highlights the foundational role of mRNA transcription in the overall protein synthesis process.