Beetle and Tatum's Genetic Discoveries

In 1941, George Beetle and Edward Tatum demonstrated that each gene encodes a specific enzyme, confirming Sir Archibald Garrod's theory of inborn errors of metabolism. Using Neurospora crassa, they showed that mutations in genes could lead to nutritional deficiencies, such as the inability to synthesize Vitamin B6. Their work laid the foundation for understanding genetic mutations' role in metabolic pathways, particularly in the synthesis of amino acids like arginine. This research provided biochemical proof that one gene is responsible for one enzyme, revolutionizing genetics and biochemistry.

What did George Beetle and Edward Tatum demonstrate through their experiments on Neurospora crassa?

• Genes do not affect enzyme production.

• Each gene encodes one enzyme.

• Each gene encodes multiple enzymes.

• Enzymes are not related to genes.

What is the significance of Neurospora being a haploid organism in genetic experiments?

• It does not affect genetic studies.

• It complicates genetic analysis.

• It simplifies the study of dominant and recessive alleles.

• It has multiple copies of each gene.

How did Beetle and Tatum induce mutations in Neurospora?

• By using chemical mutagens.

• By exposing it to ultraviolet light.

• By using X-rays.

• By altering its diet.

What was the first mutant discovered by Beetle and Tatum unable to synthesize?

• Vitamin C

• Vitamin B6

• Sugars

• Amino acids

What method did Beetle and Tatum use to identify specific metabolic pathway defects in mutants?

• Genetic sequencing

• Microscopic examination

• Nutritional supplementation

• Chemical analysis

Which amino acid's synthesis pathway was studied by Beetle and Tatum using mutants?

• Lysine

• Arginine

• Histidine

• Glutamine

What did the discovery of different mutants needing specific supplements demonstrate?

• Genes do not affect metabolic pathways.

• Each gene affects a specific step in a pathway.

• Each gene affects multiple pathways.

• All genes are identical.

What hypothesis was confirmed by Beetle and Tatum's experiments?

• One gene affects multiple enzymes.

• Genes do not encode enzymes.

• Enzymes are not related to genes.

• One gene-one enzyme hypothesis.

What did Archibald Garrod propose about hereditary diseases?

• They are caused by environmental factors.

• They are inborn errors of metabolism.

• They are caused by external infections.

• They are unrelated to metabolism.

What is the role of a gene according to Beetle and Tatum's findings?

• To encode multiple proteins.

• To have no specific role.

• To carry directions for making one protein.

• To regulate environmental factors.