A Level Biology Practice Exam

What is the genetic code made up of?

1. A sequence of three nucleic acid bases

2. A single amino acid

3. Ribosomal RNA molecules

4. Proteins

The correct answer is: A sequence of three nucleic acid bases

The genetic code is indeed made up of a sequence of three nucleic acid bases, which are known as codons. Each codon corresponds to a specific amino acid or a stop signal during protein synthesis. This triplet nature of the genetic code allows for 64 possible combinations of the four nucleotides (adenine, cytosine, guanine, and uracil in RNA) to code for the 20 different amino acids used in protein synthesis. This redundancy and specificity enable the complex and precise functioning of biological systems. Other options refer to different aspects of molecular biology but do not accurately describe the genetic code. For instance, a single amino acid is the product coded for by the codons, not the code itself. Ribosomal RNA molecules are components of ribosomes that facilitate protein synthesis, but they are not what constitutes the genetic code. Similarly, proteins are the end products of the translation process guided by the genetic code, rather than the code itself.