Question

The proof for the fact that protein synthesis occurs through ...........(gene/Mutation) was given by George Beadle and Edward Tatum.

Answer 1

Hint: 1) Protein synthesis occurs inside the ribosomes during the translation process.
2) The ribosome is the cell's protein factory.
3) Both prokaryotic and eukaryotic cells contain ribosomes. Ribosomes can also be used in conjunction with other cell organelles such as mitochondria.

Complete answer
The one gene-one enzyme theory proposes that genes function by releasing enzymes, with each gene producing a single enzyme that influences a single stage in a metabolic pathway. In an influential 1941 paper on genetic mutations in the mould Neurospora crassa, George Beadle and Edward Tatum suggested the "one gene-one enzyme hypothesis," which was later called the "one gene-one enzyme hypothesis" by their colleague Norman Horowitz.
The first correlation found between genes and enzymes was dubbed the “one gene-one enzyme” hypothesis. Since Beadle and Tatum, this theory has undergone significant revisions.
Some genes encode proteins that do not act as enzymes. Enzymes are only one kind of protein. Cells contain a large number of non-enzyme proteins, which are also encoded by genes.
Some genes encode a subunit of a protein rather than the whole protein. A gene, in general, encodes one polypeptide, or one chain of amino acids. Some proteins are made up of several polypeptides derived from various genes.

Hence, the answer will be gene.

Solution
The proof for the fact that protein synthesis occurs through genes was given by George Beadle and Edward Tatum.

Note
1) Polypeptides are not encoded by all genes. Such genes, rather than polypeptides, encode functional RNA molecules.
2) Although the "one gene-one enzyme" hypothesis isn't complete, the central premise – that a gene normally defines a protein in a one-to-one arrangement – is still useful to geneticists today.
3) Many nutritional mutants were related to complex amino acid and vitamin biosynthetic pathways by Beadle and Tatum.