Question

Why did Nirenberg and Matthaei use polynucleotide phosphorylase instead of RNA polymerase in their experiments using a cell-free system?

A) Polynucleotide phosphorylase synthesizes RNA in the 3' to 5' direction
B) RNA polymerase cannot synthesize RNA in a cell-free system
C) Polynucleotide phosphorylase can synthesize RNA without using a DNA template
D) RNA polymerase is not specific for codons

Answer 1

Nirenberg and Matthaei used polynucleotide phosphorylase instead of RNA polymerase because it can synthesize RNA without a DNA template, thus enabling the creation of RNA sequences autonomously for their experimentation.

Step-by-step explanation:

The student asked why Nirenberg and Matthaei used polynucleotide phosphorylase instead of RNA polymerase in their experiments using a cell-free system. The answer is that polynucleotide phosphorylase can synthesize RNA without using a DNA template, which is option C in the choices provided.

This capability was essential for their experiment because they wanted to create polynucleotide sequences that were not necessarily guided by the sequence of a DNA molecule. RNA polymerase, on the other hand, synthesizes RNA using a DNA template, requiring a sequence to guide the synthesis and is thus not suitable for producing random sequences of RNA.