Bases in DNA (purines and pyrimidines)

Purines

the two types of nitrogenous bases found in DNA and RNA. They have a double-ring structure. Adenine (A) and Guanine (G) are examples

Pyrimidines

the nitrogenous bases that make up the building blocks of DNA and RNA. They have a single-ring structure. Cytosine (C), Thymine (T) in DNA, and Uracil (U) in RNA

Adenine (A)

Two rings NO OXYGEN purine base that pairs with thymine (T) in DNA through two hydrogen bonds. In RNA, pairs with uracil (U).

Guanine (G)

two rings WITH oxygen a purine base that forms a base pair with cytosine (C) through three hydrogen bonds in DNA and RNA.

Cytosine (C)

one ring, with NH₂ + O. a pyrimidine base that pairs with guanine (G) through three hydrogen bonds in DNA and RNA.

Thymine (T)

one ring, with two carbonyls + CH₃ group. a pyrimidine base that pairs with adenine (A) through two hydrogen bonds specifically in DNA. It is replaced by uracil (U) in RNA.

Uracil (U)

like thymine, but without the CH₃ group. a pyrimidine base that pairs with adenine (A) in RNA, replacing thymine (T). It forms two hydrogen bonds with adenine.

Base Pairing

refers to the specific hydrogen bonding between complementary nitrogenous bases in DNA and RNA. Adenine pairs with thymine (T) or uracil (U), and guanine pairs with cytosine (C).

Hydrogen Bonds

are weak chemical bonds formed between the hydrogen atom of one molecule and a highly electronegative atom (such as oxygen or nitrogen) of another molecule. They contribute to the stability of DNA's double helix structure through base pairing.

Base Sequence

refers to the order of nitrogenous bases (A, T, C, G) along a DNA or RNA strand. It encodes genetic information and determines the genetic code for protein synthesis.