Question detail
Explain the condensation reaction that forms the sugar-phosphate backbone of DNA. Include the role of the phosphate and sugar molecules in your answer.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
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Style
Topic
Amino acids, proteins and DNA (A-level only)
Question
Explain the condensation reaction that forms the sugar-phosphate backbone of DNA. Include the role of the phosphate and sugar molecules in your answer.
Answer
In a condensation reaction, a phosphate group reacts with the hydroxyl group of a sugar molecule, resulting in the formation of a phosphodiester bond. This reaction releases a molecule of water and links the sugar and phosphate, creating the sugar-phosphate backbone of DNA.
Explanation
This answer is strong because it clearly describes the chemical process involved in forming the sugar-phosphate backbone, highlighting the role of both the phosphate and sugar molecules. The question tests the understanding of condensation reactions in the context of DNA structure.
Common mistake
Confusing the Backbone Components
Students often confuse the components of the sugar-phosphate backbone in DNA, thinking that the sugar and phosphate groups are interchangeable.
To clarify, remember that the sugar (deoxyribose) and phosphate groups are distinct components. The sugar is linked to the phosphate group through a condensation reaction, forming a covalent bond. This can be summarized as: sugar + phosphate → sugar-phosphate backbone. Ensure you can identify each component and their roles in the structure.
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