Purine Biosynthesis

The video tutorial explains the synthesis of PRP and its role in nucleotide synthesis, focusing on the differences between purine and pyrimidine synthesis. It highlights the energetic cost of purine synthesis, requiring multiple ATPs and other molecules. The connection between histidine and purine synthesis is discussed, noting the similarities in their pathways. The tutorial outlines the steps in purine synthesis, leading to the formation of IMP, which can be converted into AMP or GMP. The video concludes with a comparison of the shorter pyrimidine synthesis pathway, emphasizing the structural differences between purines and pyrimidines.

What is the primary difference between purine and pyrimidine synthesis?

• Purine synthesis occurs in the cytoplasm, while pyrimidine synthesis occurs in the nucleus.

• Purine rings are built directly on the ribose ring, while pyrimidine rings are synthesized separately and then attached.

• Purine synthesis requires more enzymes than pyrimidine synthesis.

• Pyrimidine synthesis uses more ATP than purine synthesis.

How many ATP molecules are required to synthesize one IMP from ribose 5 phosphate?

• 3 ATP molecules

• 4 ATP molecules

• 5 ATP molecules

• 6 ATP molecules

Which molecule is NOT used in the purine synthesis pathway?

• Aspartate

• Serine

• Glycine

• Glutamine

What is the significance of the intermediate ICAR in histidine synthesis?

• It is used to synthesize ATP.

• It is shunted into the purine synthesis pathway in bacteria.

• It is a byproduct of amino acid synthesis.

• It is only found in mammals.

Why is pyrimidine synthesis shorter than purine synthesis?

• Pyrimidine synthesis uses fewer enzymes.

• Pyrimidines have one ring, while purines have two.

• Pyrimidines are synthesized in the nucleus, which speeds up the process.

• Pyrimidines have two rings, while purines have one.

What is required to convert IMP to AMP?

• GTP

• ATP

• UTP

• CTP

Which enzyme is involved in the conversion of IMP to GMP?

• Adenylosuccinate synthetase

• IMP dehydrogenase

• XMP glutamine amido transferase

• Adenylosuccinate lyase