The “double” in the double helix means that DNA is found in a double-stranded form – 2 single-stranded chains of DNA stuck to each other via hydrogen bonding of the base pairs. The 2 single-strands are anti-parallel to each other. Going from 5′ to 3′ of one strand means going from 3′ to 5′ of the other strand. The “helix” in the double helix means that the entire thing is wound up what enzyme is responsible for unwinding dna during replication a spiral. The phosphate group gives DNA its acidity.
A forms 2 hydrogen bonds with T. G forms 3 hydrogen bonds with C. DNA with high GC content will be harder to break apart. Complementary strands of DNA hydrogen bond with each other.
5′-ATGC-3′ will be complementary to 5′-GCAT-3′ or 3′-TACG-5′, but NOT 5′-TACG-3′. Because of the complementary nature of base pairing, DNA can transmit genetic information through replication. First, the double stranded DNA must separate, or unwind. DNA ahead of the replication fork. Helicase is responsible for unwinding the DNA at the replication fork. DNA unwound after the helicase.