Biology Chapter 10.2

Nitrogen Base

a nitrogen-containing organic compound that has the chemical properties of a base, especially a pyrimidine or purine:

Guanine

a purine base, C 5 H 5 N 5 O, that is a fundamental constituent of DNA and RNA, in which it forms base pairs with cytosine. Symbol: G.

Adenine

a purine base, C 5 H 5 N 5, one of the fundamental components of nucleic acids, as DNA, in which it forms a base pair with thymine, and RNA, in which it pairs with uracil

Cytosine

a pyrimidine base, C 4 H 5 N 3 O, that is one of the fundamental components of DNA and RNA, in which it forms a base pair with guanine. Symbol: C.

Thymine

a pyrimidine base, C 5 H 6 N 2 O 2, that is one of the principal components of DNA, in which it is paired with adenine. Symbol: T.

Base Pairing Rule

constraints imposed by the molecular structure of DNA and RNA on the formation of hydrogen bonds among the four purine and pyrimidine bases such that adenine pairs with thymine or uracil, and guanine pairs with cytosine.

Complementary Base Pairs

either of the nucleotide bases linked by a hydrogen bond on opposite strands of DNA or double-stranded RNA: guanine is the complementary base of cytosine, and adenine is the complementary base of thymine in DNA and of uracil in RNA.

Purine

one of several purine derivatives, especially the bases adenine and guanine, which are fundamental constituents of nucleic acids.

Pyrimidine

one of several pyrimidine derivatives, especially the bases cytosine, thymine, and uracil, which are fundamental constituents of nucleic acids.

Double Helix

the spiral arrangement of the two complementary strands of DNA.

Deoxyribose

the sugar, HOCH 2 (CHOH) 2 CH 2 CHO, obtained from DNA by hydrolysis.