Final answer:
DNA is composed of two strands forming a double helix, with nucleotides containing a deoxyribose sugar, a phosphate group, and a nitrogenous base. Adenine pairs with thymine and guanine pairs with cytosine, maintaining the structure's uniformity and function.
Step-by-step explanation:
Understanding DNA's Structure and Complementary Base Pairing
Deoxyribonucleic acid (DNA) is the hereditary material in humans and almost all other organisms. DNA molecules consist of two polynucleotide chains that form a double helix. Each nucleotide in these chains contains a deoxyribose sugar, a phosphate group, and a nitrogenous base. The structure's stability derives from complementary base pairing, where the purine bases, adenine (A) and guanine (G), pair with the pyrimidine bases, thymine (T) and cytosine (C), respectively. Adenine and thymine form two hydrogen bonds while cytosine and guanine form three, which ensures a uniform distance between the two DNA chains. This complementary sequencing of bases results in DNA's uniform shape and ability to carry genetic information accurately.