Each DNA molecule contains many genes , and the genome of an organism contains all of the genes. A gene is a functional unit of heredity. The human genome contains approximately 30,000 genes . Intron sequences, which have no protein coding function, are interspersed with genes. Human Genes Make Proteins Humans can synthesize about 80,000 different kinds of proteins from the 30,000 genes.
Proteins are large, complex molecules made of long chains of amino acids .
Twenty different kinds of amino acids are found in proteins. The genetic code is thus a series of codons that specify which amino acids are required to make up specific proteins. Part of the Central Dogma involves understanding how the protein is encoded from the DNA molecule. In humans the 3 billion base pairs that constitute the human genome are arranged on 24 separate chromosomes . All human genes are arranged linearly along the chromosomes.