The double helix structure of DNA and the base-pairing rule allow DNA to function as a hereditary molecule. 

The base-pairing rule limits the interactions between nitrogenous bases: adenine (A) can pair only with thymine (T), while guanine (G) only with cytosine (C) in the opposite strand. If we have the sequence of only one strand available, we can easily predict the sequence of the opposite strand as the two strands of the DNA double helix must be complementary to each other. 

Due to this complementary nature of base pairing, DNA can transmit genetic material through replication. During DNA replication and cell division, cells can make two identical copies of DNA from each DNA strand and each daughter cell gets identical copies of DNA. In this way, organisms transmit all the necessary information to their progenies to build themselves from scratch. DNA carries this genetic information in the sequence of nucleotides. These sequences determine the order of amino acids in a protein. This is the direct connection between genes and traits. 

Key Points

• Genetic information is transmitted in the sequence of nucleotides into the next generations.

• Faithful transmission of genetic information becomes possible by the double helix nature of DNA and also base-pairing rule which allows helices (or strands) to be complementary to each other. 

Key Terms

Nitrogenous bases: Organic molecules, which are part of the nucleotides in DNA, showing base-like chemical properties.

Genetic material: A material that carries hereditary information to build the organism in each generation.

Base Pairing Rule (Chargaff’s Rule): Each base can only bond with one other, A with T and C with G.

Double helix: The structure of DNA which looks like a twisted staircase.

Replication: The process by which DNA makes a copy of itself during cell division.

Gene: The basic physical and functional unit of heredity.

Trait (a.ka. phenotype): A physical feature of an organism.