The specifications for how information, stored in nucleic acid sequence (base sequence), is translated into protein sequence (amino acid sequence). The start, stop, and order of amino acids of a protein is specified by consecutive triplets of nucleotides called codons (codon).
The set of triplet code words in DNA coding for all of the amino acids. There are more than 20 different amino acids and only four bases (adenine, thymine, cytosine, and guanine). The mRNA code is a triplet code, that is, each successive “frame” of three nucleotides (sometimes called a codon) of the mRNA corresponds to one amino acid of the protein. This rule of correspondence is the genetic code. The genetic code consists of 64 entries—the 64 triplets possible when there are four possible nucleotides, each of which can be at any of three places (4x4x4 = 64). A triplet code was required because a doublet code would have only been able to code for (4×4=16) sixteen amino acids. A triplet code allows for the coding of 64 theoretical amino acids. Since only a little over 20 exist, there is some redundancy in the system. Hence some certain amino acids are coded for by two or three different triplets.
The hereditary characteristics contained within the germ cells of both sexes.
The characteristics of the DNA of a cell which are passed on when the cell divides and so are inherited by a child from its parents.
The sequence of purine and pyrimidine bases that are in a specific order and that dictate the amino acid sequence of all proteins synthesized by cells.
The biochemical language by which all known organisms transfer genetic information. DNA (deoxyribonucleic acid) contains the genetic code to communicate the information or instructions that allow specific genes to function. A genetic code is present in all animals, plants, fungi, bacteria, and viruses.
The information carried by DNA that determines the sequence of amino acids in every protein and thereby controls the nature of all proteins made by the cell. The genetic code is expressed by the sequence of nucleotide bases along the DNA molecule, a unit of three consecutive bases (a codon) coding for each amino acid. The code is translated into protein at the ribosomes (see transcription, translation). Changes in the genetic code result in the insertion of incorrect amino acids in a protein chain, giving a mutation.
A table showing the correspondence of 1) every possible triplet sequence of messenger ribonucleic acid (mRNA) (codon) and 2) its effect on a chemical process known as protein synthesis in the body.
The message set out sequentially along the human chromosomes. The human gene map has been constructed through the work of the international, collaborative human genome project. Genes are responsible for the protein synthesis of the cell: they instruct the cell how to make a particular polypeptide chain for a particular protein.
The sequence of bases in the DNA of living cells that provides the instructions for the synthesis of polypeptides (proteins) from amino acids. These instructions are contained in 64 nucleotide triplet sequences, called codons, 61 of which specify the 20 amino acids present in proteins and 3 of which halt the addition of amino acids to a polypeptide being synthesized. These three triplets are called termination codons. The genetic code is the same in all living things, except that in some viruses and fungi, it is contained in RNA rather than DNA.
Inherited directives stored within genes guide cellular activities and, as a result, influence the growth and operation of the body. Each gene within a chromosome carries encoded instructions for a cell to manufacture a protein, which performs a specific role in the body.
The DNA that forms genes is composed of two lengthy, entwined strands, each featuring a sequence of four chemical compounds known as nucleotide bases. These bases include adenine, thymine, cytosine, and guanine, frequently abbreviated as A, T, C, and G. They connect in pairs, termed base-pairs, thus linking the two strands of the DNA molecule. The order of these bases along the DNA strands comprises the genetic code. In the process of protein synthesis, ribonucleic acid (RNA) assists in interpreting this code to generate the protein.