Final answer:
In DNA, cytosine pairs with guanine, which is determined by the hydrogen bonding pattern where three hydrogen bonds connect these two bases.
Step-by-step explanation:
Cytosine pairs with guanine (G) in DNA. The pairing of these nitrogenous bases is critical for the structure of DNA and is governed by specific hydrogen bonding patterns. Cytosine, which is a pyrimidine, forms three hydrogen bonds with guanine, a purine, embodying Chargaff's rules that state purines always base pair with pyrimidines to maintain the consistent width of the DNA double helix. This complementary base pairing is essential for DNA replication and for maintaining the genetic code.
Cytosine pairs with guanine in DNA. They form a complementary base pair where cytosine, a pyrimidine, pairs with guanine, a purine. This base pairing is stabilized by hydrogen bonds, with cytosine and guanine forming three hydrogen bonds between them.