The steps of the DNA ladder are made of two nitrogenous bases that are held together by either two or three weak hydrogen bonds.
DNA (deoxyribonucleic acid) is a hereditary material that carries genetic instructions used in building and maintaining all living organisms and many viruses. DNA is formed by base pairs joined to a sugar-phosphate backbone. The rungs of the DNA ladder contains four nitrogenous bases; adenine, thymine, cytosine and guanine. Each rung of the ladder is made up of two nitrogenous bases that are held together by weak hydrogen bonds.