Each nucleotide base can pair with only one of the three other bases, thereby determining the sequence of a complementary strand.
Hydrogen bonds form between bases to make the component strands of DNA into a double helix.
Complementary DNA s are important laboratory tools which serve as DNA probes and assist with the isolation and study of individual genes. Two complementary strands of single stranded DNA will join to form a double-stranded molecule. This occurs because of some shared homology between the probe and the DNA sequence. This molecule is a constituent of chromosomes and is the carrier of the genetic code. During the gene mapping process, genetic markers located at or near important genes are identified.