Crick, Brenner et al. experiment
Encyclopedia
The Crick, Brenner, Barnett, Watts-Tobin experiment of 1961 was a scientific experiment performed in 1961 by Francis Crick
, Sydney Brenner
, Leslie Barnett
and R.J. Watts-Tobin. They demonstrated that three bases of DNA code for one amino acid in the genetic code
. The experiment elucidated the nature of gene expression
and frameshift mutation
s.
In the experiment, proflavin-induced mutation
s of the T4 bacteriophage
gene, rIIB, were isolated. Proflavin causes mutations by inserting itself between DNA bases, typically resulting in insertion or deletion of a single base pair.
The mutants produced by Crick and Brenner could not produce functional rIIB protein because the insertion or deletion of a single nucleotide caused a frameshift mutation
. Mutants with two or four nucleotides inserted or deleted were also nonfunctional. However, the mutant strains could be made functional again by using proflavin to insert or delete a total of three nucleotides. This proved that the genetic code uses a codon of three DNA bases that corresponds to an amino acid
.
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...
, Sydney Brenner
Sydney Brenner
Sydney Brenner, CH FRS is a South African biologist and a 2002 Nobel prize in Physiology or Medicine laureate, shared with H...
, Leslie Barnett
Leslie Barnett
Leslie Barnett was a British biologist born in London, together with Francis Crick, Sydney Brenner and Richard J. Watts-Tobin genetically demonstrated the triplet nature of the code of protein translation through the Crick, Brenner, Barnett, Watts-Tobin et al...
and R.J. Watts-Tobin. They demonstrated that three bases of DNA code for one amino acid in the genetic code
Genetic code
The genetic code is the set of rules by which information encoded in genetic material is translated into proteins by living cells....
. The experiment elucidated the nature of gene expression
Gene expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...
and frameshift mutation
Frameshift mutation
A frameshift mutation is a genetic mutation caused by indels of a number of nucleotides that is not evenly divisible by three from a DNA sequence...
s.
In the experiment, proflavin-induced mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
s of the T4 bacteriophage
Bacteriophage
A bacteriophage is any one of a number of viruses that infect bacteria. They do this by injecting genetic material, which they carry enclosed in an outer protein capsid...
gene, rIIB, were isolated. Proflavin causes mutations by inserting itself between DNA bases, typically resulting in insertion or deletion of a single base pair.
The mutants produced by Crick and Brenner could not produce functional rIIB protein because the insertion or deletion of a single nucleotide caused a frameshift mutation
Frameshift mutation
A frameshift mutation is a genetic mutation caused by indels of a number of nucleotides that is not evenly divisible by three from a DNA sequence...
. Mutants with two or four nucleotides inserted or deleted were also nonfunctional. However, the mutant strains could be made functional again by using proflavin to insert or delete a total of three nucleotides. This proved that the genetic code uses a codon of three DNA bases that corresponds to an 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...
.
See also
- Nirenberg and Leder experimentNirenberg and Leder experimentThe Nirenberg and Leder experiment was a scientific experiment performed in 1964 by Marshall W. Nirenberg and Philip Leder. The experiment elucidated the triplet nature of the genetic code and allowed the remaining ambiguities codons in the genetic code to be deciphered.In this experiment, using a...
- Nirenberg and Matthaei experimentNirenberg and Matthaei experimentThe Nirenberg and Matthaei experiment was a scientific experiment performed on May 15, 1961, by Marshall W. Nirenberg and his post doctoral fellow, Heinrich J. Matthaei...