Concept explainers
Interpretation:
Two substrates that contribute to the structure of the pyrimidine ring should be determined.
Concept introduction:
Pyrimidine is a heterocyclic nitrogenous base, which is found in the DNA and RNA. DNA has cytosine and thymine as pyrimidines, and RNA has uracil and cytosine has pyrimidines. It is a six-membered ring that contains two nitrogen atoms at 1 and 3 positions.

Answer to Problem 1P
Option (c), aspartate and carbamoyl phosphate.
Explanation of Solution
Reason for correct option:
Option (c) is aspartate and carbamoyl phosphate. Only two precursors, carbamoyl-P and aspartate are required for the formation of pyrimidine. For all the pyrimidines, only these two precursors are required. Hence, this option is correct.
Reasons for incorrect options:
Option (a) is glutamate and carbamoyl phosphate. Glutamate is the product of the reaction between carbamoyl-phosphate and glutamine amide. Aspartate is the main reactant for the production of pyrimidine. Hence, this option is incorrect.
Option (b) is aspartate and glutamine. Aspartate and glutamine are used in the production of purine and not for pyrimidine. Hence, this option is incorrect.
Option (d) is glycine and carbamoyl phosphate. Glycine is one of the main substrates used to produce purine. Hence, this option is incorrect.
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Chapter 25 Solutions
BIOCHEMISTRY
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