AAMC FL Practice Exam

What distinguishes the structures of GTP and ATP?

1. GTP has a ribose sugar, ATP does not

2. GTP has one fewer phosphate than ATP

3. Both have three phosphates attached to a ribose sugar

4. GTP contains a phenyl group, ATP does not

The correct answer is: Both have three phosphates attached to a ribose sugar

GTP and ATP are both nucleotides that play crucial roles in cellular metabolism and signaling, and they share a similar structural framework. The correct answer highlights that both GTP and ATP have three phosphate groups attached to a ribose sugar, confirming their categorization as triphosphate nucleotides. Both molecules consist of a ribose sugar backbone and contain an adenine (for ATP) or guanine (for GTP) nitrogenous base. The presence of three phosphate groups is what allows them to act as energy carriers within the cell. The high-energy bonds between the phosphates are crucial for energy transfer in biochemical reactions. The other options present distinct inaccuracies. The notion that GTP has a ribose sugar while ATP does not misrepresents their structure, as both contain ribose. The idea that GTP has one fewer phosphate than ATP is incorrect, as both have the same number of phosphate groups. Finally, the claim that GTP contains a phenyl group while ATP does not also falls short, as neither GTP nor ATP contains phenyl groups in their structure. Understanding the similarity in the basic structure of GTP and ATP helps clarify their functional roles in cellular processes.