Explain complementary base pairing using hydrogen bonds.

In the subtopic DNA chemistry (A-level only), this AQA A-Level Chemistry 7405 learning objective focuses on explain complementary base pairing using hydrogen bonds. It belongs to Amino acids, proteins and DNA (A-level only), so revision should stay anchored to this exact subtopic rather than drifting into a generic GCSE-level chemistry summary. Approved keywords to use include complementary base pair, base. Hydrogen bonds. means weak attractions between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom, crucial for stabilizing the DNA double helix structure Avoid the mistake of students often confuse the specific hydrogen bonds formed between complementary bases in DNA, such as pairing adenine with thymine and cytosine with guanine; instead, to clarify, remember that adenine (A) forms two hydrogen bonds with thymine (T), while cytosine (C) forms three hydrogen bonds with guanine (G). This can be summarized as: A-T (2 H-bonds) and C-G (3 H-bonds). Therefore, when explaining complementary base pairing, ensure to specify the number of hydrogen bonds formed between each pair For exam answers, remember that adenine pairs with thymine and guanine pairs with cytosine through hydrogen bonds