key term - Nitrogenous bases

Definition

Nitrogenous bases are the four types of molecules (adenine, thymine, cytosine, and guanine) that make up the "rungs" or steps on the DNA ladder. They have specific pairing rules - adenine pairs with thymine and guanine pairs with cytosine.

Related terms

DNA molecule:

A DNA molecule is a long, double-stranded helix structure that contains the genetic information of an organism. It consists of two nucleotide strands wrapped around each other in a spiral shape.

Nucleotide:

A nucleotide is the basic unit or building block of DNA. It consists of three components: a sugar molecule (deoxyribose), a phosphate group, and one of four nitrogenous bases (adenine, thymine, cytosine, or guanine).

Base pairing:

Base pairing refers to the specific interaction between complementary nitrogenous bases in DNA. Adenine always pairs with thymine (A-T), while guanine always pairs with cytosine (G-C).