Sequence hypothesis
Encyclopedia
The sequence hypothesis was first formally proposed in a review “On Protein Synthesis” by Francis Crick
in 1958. It states that the sequence of bases in the genetic material (DNA
or RNA
) determines the sequence of amino acid
s for which that segment of nucleic acid codes, and this amino acid sequence determines the three dimensional structure into which the protein
folds. The three dimensional structure of a protein is required for a protein to be functional. This hypothesis then lays the essential link between information stored and inherited in nucleic acids to the chemical processes which enable life to exist.
Or, as Crick put it in 1958:
“…..In its simplest form it (the Sequence Hypothesis) assumes that the specificity of a piece of nucleic acid
is expressed solely by the sequence of its bases
, and that this sequence is a (simple) code for the amino acid sequence of a particular protein.
This hypothesis appears to be rather widely held. Its virtue is that it unites several remarkable pairs of generalisations:
• the central biochemical importance of proteins and the dominating role of genes
, and in particular of their nucleic acid
• the linearity of protein molecules (considered covalently) and the genetic linearity within the functional gene……
• the simplicity of the composition of protein molecules and the simplicity of the nucleic acids.”
This description is further amplified in the article and, in discussing how a protein folds up into it’s three-dimensional structure, Crick suggested that “the folding is simply a function of the order of the amino acids” in the protein.
Francis Crick
Francis Harry Compton Crick OM FRS was an English molecular biologist, biophysicist, and neuroscientist, and most noted for being one of two co-discoverers of the structure of the DNA molecule in 1953, together with James D. Watson...
in 1958. It states that the sequence of bases in the genetic material (DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
or RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
) determines the sequence of amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s for which that segment of nucleic acid codes, and this amino acid sequence determines the three dimensional structure into which the protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
folds. The three dimensional structure of a protein is required for a protein to be functional. This hypothesis then lays the essential link between information stored and inherited in nucleic acids to the chemical processes which enable life to exist.
Or, as Crick put it in 1958:
“…..In its simplest form it (the Sequence Hypothesis) assumes that the specificity of a piece of nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...
is expressed solely by the sequence of its bases
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
, and that this sequence is a (simple) code for the amino acid sequence of a particular protein.
This hypothesis appears to be rather widely held. Its virtue is that it unites several remarkable pairs of generalisations:
• the central biochemical importance of proteins and the dominating role of genes
Gênes
Gênes is the name of a département of the First French Empire in present Italy, named after the city of Genoa. It was formed in 1805, when Napoleon Bonaparte occupied the Republic of Genoa. Its capital was Genoa, and it was divided in the arrondissements of Genoa, Bobbio, Novi Ligure, Tortona and...
, and in particular of their nucleic acid
• the linearity of protein molecules (considered covalently) and the genetic linearity within the functional gene……
• the simplicity of the composition of protein molecules and the simplicity of the nucleic acids.”
This description is further amplified in the article and, in discussing how a protein folds up into it’s three-dimensional structure, Crick suggested that “the folding is simply a function of the order of the amino acids” in the protein.