Chapter 4, Problem 4.1CC

Why do scientists currently believe that RNA, rather than DNA, was the informational molecule in the first cells?

Summary Introduction

To determine: The reason the scientists believe RNA and not DNA to be the informational molecule in the first cells.

Introduction: Cell is the basic “fundamental unit” of life. Cells can either be unicellular or multicellular. The organisms with one cell are referred to as unicellular organisms, whereas the organisms with more than one cell are termed as multicellular organisms. The genetic information is passed on from one generation to the next with the help of genes.

Explanation of Solution

According to the central dogma, the information is transcribed from DNA to RNA and then it is finally translated from RNA into proteins. DNA acts as an informational molecule and in order to transfer information it needs to get replicated. DNA replication takes place with the help of certain pre-existing enzymes which are produced with the help of information found in DNA. Monomer subunits of RNA are responsible for producing monomer subunits of DNA with the help of certain enzymes. Ribozymes are catalytic RNAs which help in RNA replication without the requirement of enzymes whose information is found in DNA.

Therefore, this is the main reason that the scientists think that RNA and not DNA was the informational molecule in first cells as formation of certain enzymes which help in the production of DNA has been done from the information encoded within the DNA and RNA subunits act as precursors for enzymatic production of building blocks of DNA as ribozymes assist in RNA replication without the requirement of enzymes encoded by DNA.