Genes and Gene Therapy

Genes are chemical compounds that act as genetic codes. They instruct cells to make proteins.

Each gene is a collection of DNA (deoxyribonucleic acid) in sequence. DNA molecules are long double-he-lix molecules resembling a spiral staircase. The steps in the spiral staircase were fixed at conception when the individual inherited 46 chromosomes from two parents (23 from each). The steps consist of pairs of four types of chemicals. Each is a molecule called a base (nucleotide). The four types are adenine (A), thymine (T), guanine (G), and cytosine (C).

The genetic code of each individual is written in triplicate so that the combination of A with G or G with C or T creates sequences such as AAA, or AGT or GCT. The genetic codes are so arranged that they instruct the manufacturing of one of twenty amino acids. For example, the sequence GCT is the code for the manufacture of amino acid lysine.

Each gene codes for the manufacture of one protein. This means that each gene is a stretch of DNA in a coded sequence. The sizes of genes vary. The size depends upon the size of the molecule that it is coded to manufacture.

Obvious inherited characteristics are hair, skin, or eye coloring. These inherited characteristics are the product of the genes acquired at conception. Some traits are regulated by more than one gene.

Each gene contains a set of nucleic acid molecules that comprise a set. The segment contains the coded information needed to produce a functional RNA (ribonucleic acid). The gene uses the coded information in an orderly manner. The code includes information in the segments that acts as rules directing the manufacturing of another molecular product. The gene also has in is program regions that carry instructions on how to function.

The genetic makeup of an individual is a genotype. The genotype contains information for the physical development of the body. Phenotype is the name for the manner in which the genotype is expressed (phenotype expression). The interaction of the genes with each other and with the environment (e.g., food available, minerals in water, and other environmental factors) guides the physical development of the individual. Genes are the units of genetic inheritance. Often more than one gene is involved in the expression of the genetically determined characteristics of an individual. For some reason genes normally contain noncoding regions.