The nucleus of every living cell of the corn plant has 30-40 thousand genes on each chromosome. Each gene is composed of a string of four nucleic bases (adenine, cytosine, guanine and thymine) the order of which is the DNA code for that gene. The DNA structure is a double strand of these nucleic bases wound around a sugar molecule (deoxyribose) and a phosphate molecule. The strands are held together by the attraction of bonds of adenine to thymine and cytosine to guanine. A single gene may include a string of hundreds to thousands of these 4 nucleic bases.
When a gene is transcribed, the double helix strand is separated, and the single strand copied onto a different sugar (ribose) and phosphate, moved from the cell nucleus to the ribosome in the cytoplasm. Amino acids from the cytoplasm are attached to each other according to the sequence of the nucleic acids. Three consecutive nucleic bases code for a single amino acid. The string of amino acids become a protein once the genetic code for a single gene is read in the ribosome.
Amino acids are compounds of nitrogen, hydrogen carbon and oxygen atoms attached in 20 distinct patterns, including differing side branches. A single protein molecule often includes hundreds of amino acids combined in complex shapes because of the different charges of those side branches in each amino acid. Many of the proteins function in cells as enzymes affecting all cell metabolism.
The complexity of thousands of genes each composed of strings of 4 bases translated into strings of amino acids to form a single protein that may affect the process of producing a single cell compound is overwhelming. The stability of the system is responsible for corn plants looking like corn plants. Probably 95-99% of the genes in all corn plants are similar.
Genetic variability allowing the differing expression of favored traits affecting timing of flowering, silk extension, water and mineral uptake, leaf size and shape, disease resistance may involve only 1-5% of the DNA code. Selection of random assortments of the DNA codes has led to the variation among varieties within the corn species. Combining the inbreds to maximize the expression of favored traits is the job of the corn breeder. Providing a dependable system of genetics is the responsibility of the cell nucleus and translation of the gene is up to the cell cytoplasm.
About Corn Journal
The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.