Garrod's information about the enzyme alteration resulting in alkaptonuria led to further understanding of these types of metabolic pathways in humans. phenylketonuria (pku) occurs when another enzyme in the pathway is altered or missing, resulting in a failure of phenylalanine (phe) to be metabolized to another amino acid: tyrosine. tyrosine is an earlier substrate in the pathway altered in alkaptonuria. how might pku affect the presence or absence of alkaptonuria?

The hershey and chase experiments involved the preparation of two different types of radioactively labeled phage. which of the following best explains why two preparations were required? a. the bacteriophage used in the experiments was a t2 phage. b. it was necessary that each of the two phage components, dna and protein, be identifiable upon recovery at the end of the experiment. c. each scientist had his own method for labeling phage, so each conducted the same experiment using a different isotope. d. establishing the identity of the genetic material required observation of two phage generations.