Page 98 - Demo 1

NUCLEIC ACIDS

Nucleic acids are key biological molecules in the connuity of life. The
two main types of nucleic acids are deoxyribonucleic acid (DNA) and
ribonucleic acid (RNA).

Nucleic acids are long polymers of repeang monomers called
nucleodes. Each nucleode consists of three parts: a five-carbon sugar, a
phosphate group, and an organic nitrogen-containing base. The phosphate is
the –PO4 funconal group. The sugar is either deoxyribose or ribose;
deoxyribose has one less oxygen than ribose. Each nucleode of DNA contains
one of four bases: adenine (A), guanine (G), cytosine (C), or thymine (T). In
RNA, thymine is replaced by uracil (U).

Figure 46. Structure of a Nucleode
Source: https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/198/2016/
11/23212722/3-1-10.jpeg

DNA (Deoxyribonucleic Acid): Informaon Storage

DNA is the genec material found in all living organisms, ranging from
unicellular bacteria to mulcellular mammals. Its main purpose is to store genec
informaon. Each DNA molecule is composed of several genes, and genes
specify the sequence of amino acids in proteins.

DNA is shaped like a double helix, where two polynucleode chains are
wound around each other. In each strand, the backbone of the molecule is
composed of phosphates bonded to sugars, and the bases project to the inside.
Complementary base-pairing occurs in a DNA molecule such that the base
guanine is always paired with cytosine, and the base adenine is always paired

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