Question

Examine the simple metabolic pathway in the figure. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?

a) 1
b) 2
c) 3
d) 4

Answer 1

According to Beadle and Tatum's hypothesis, the 'one gene-one enzyme' hypothesis, the number of genes necessary for a metabolic pathway is equal to the number of enzymes in that pathway.

Step-by-step explanation:

According to Beadle and Tatum's hypothesis, the 'one gene-one enzyme' hypothesis, each gene is necessary for encoding one enzyme in a metabolic pathway. Based on their experiments with arginine mutants, Beadle and Tatum concluded that each mutant was defective in a different gene encoding a different enzyme in the arginine biosynthesis pathway. Therefore, according to their hypothesis, the number of genes necessary for a metabolic pathway is equal to the number of enzymes in that pathway. In the given figure, there are three different enzymes shown in the arginine biosynthesis pathway. Therefore, the correct answer is c) 3.