Why did scientists many years ago believe that protein was the storage molecule for genetic information, instead of DNA?

Many years ago scientists believed that protein, DNA is not the genetic material because of many reasons like DNA is made up of only four type of nucleotides while proteins are made up of 20 different types of amino acids. So the building blocks of protein are way high than DNA.

Most of the cellular function is performed by proteins, not DNA. The three-dimensional shape of protein is much higher than nucleic acid. So as protein heterogeneity was high therefore it was considered as a molecule of genetic information instead of DNA.

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.