Question

Significant in the deciphering of the genetic code was the discovery of the enzyme polynucleotide phosphorylase. What is this enzyme used for?

1) manufacture of synthetic RNA for cell-free systems
2) ribosomal translocation
3) peptide bond formation
4) production of ribosomal proteins
5) degradation of RNA

Answer 1

Polynucleotide phosphorylase is an enzyme used to manufacture synthetic RNA for cell-free systems, which was crucial in understanding the genetic code. It catalyzes the polymerization of ribonucleotides into RNA without a DNA template.

Step-by-step explanation:

The enzyme polynucleotide phosphorylase was significant in the deciphering of the genetic code. It is used for the manufacture of synthetic RNA for cell-free systems. This enzyme is not involved in ribosomal translocation, peptide bond formation, the production of ribosomal proteins, or the degradation of RNA.

How do RNA Polymerases Work?

RNA polymerases, including polynucleotide phosphorylase, synthesize RNA using a DNA or RNA template, a process essential for the flow of genetic information within a cell from DNA to RNA (transcription). Unlike traditional DNA-dependent RNA polymerases that require a DNA template and transcription factors, polynucleotide phosphorylase can catalyze the polymerization of ribonucleotides into RNA without a template. This enables the production of synthetic RNA polymers, which was crucial for research on the genetic code.

By adding ribonucleotides in a random sequence, polynucleotide phosphorylase was instrumental in the early experiments that eventually led to the understanding of the correspondence between nucleotide triplets and amino acids, further supported by experiments such as those conducted by Nirenberg and Matthaei in 1961.