Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

What discovery in the 1950s improved the understanding of DNA replication and protein synthesis?

1. Structure of DNA as a single strand

2. Structure of DNA as a double helix

3. Discovery of RNA's role in protein synthesis

4. Invention of DNA sequencing technology

The correct answer is: Structure of DNA as a double helix

The discovery of DNA as a double helix in the 1950s was a pivotal moment in molecular biology. This structural revelation, made by James Watson and Francis Crick, provided critical insights into how DNA replicates and encodes genetic information. The double helix model explained how the two strands of DNA could separate and serve as templates for the synthesis of copies of DNA during replication. Each strand can direct the synthesis of a new complementary strand, ensuring the accurate transfer of genetic information from one generation to the next. Furthermore, understanding that DNA's double helical structure allows for the precise pairing of nucleotide bases (adenine with thymine and cytosine with guanine) underscored how genetic instructions are faithfully preserved and transmitted. This model also laid the groundwork for understanding how messenger RNA (mRNA) is synthesized from DNA and how this mRNA is subsequently translated into proteins, an essential process for all living organisms. While other options mention significant aspects of genetic research, none are as foundational in shaping the understanding of DNA replication and protein synthesis as the double helix structure revealed during this era.