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DNA As A Code

DNA contains the instructions, or code, to make molecules essential to the development, functioning, and reproduction of living things. Sections of DNA that code for other molecules are called genes. Genes can vary from hundreds of nucleotides long to millions of nucleotides long.

Some genes code for molecules called proteins. The sequence of bases in a single strand of these genes — their code — is read by the cell’s protein-making machinery. The cell reads the code three bases at a time. Each set of three bases codes for an amino acid. Many amino acids bonded together in a specific order make up a protein.

On the left-hand side is a single strand of DNA with 15 labeled bases. Every group of three bases has an arrow pointing to the right of it. To the right of these arrows, the sequence of the 15 bases is repeated, with the bases grouped into threes. From each group of three bases, there is another arrow with three dots in the middle leading to a yellow circle with a letter in it. A wiggling black line connects these circles in a chain labeled as an "Amino acid chain." From top to bottom, their letters read A, G, R, N, and T.

Figure1. Translating the Code

How exactly a gene is read by the cell to make a protein is complex. The process consists of two major steps: transcription and translation.

The majority of the DNA sequence of a human, known as the human genome, does not code for other molecules. The function of much of this non-coding DNA is unknown; however, some of it is involved in regulating protein production and controlling DNA’s organization in the cell.

Referred from:

Article
Introduction to Proteins