Reading frame
Encyclopedia
In biology
, a reading frame is a way of breaking a sequence of nucleotides in DNA
or RNA
into three letter codons which can be translated
in amino acids. There are 3 possible reading frames in an mRNA strand: each reading frame corresponding to starting at a different alignment. Double stranded DNA
has six different reading frames molecule due to the two strands from which transcription is possible - three of them reading forward and three of them reading backwards.
The existence of multiple reading frames leads to the possibility of overlapping gene
s and there may be many of these in bacteria fungi parenthesis. Some viruses e.g. Hepatitis B virus
and BYDV use several overlapping genes in different reading frames.
In rare cases a translating ribosome
may shift from one frame to another, a translational frameshift
. It is distinct from a frameshift mutation
as the nucleotide sequence (DNA or RNA) is not altered only the frame in which it is read.
An open reading frame
(ORF) is a reading frame that contains a start codon
, and a subsequent region which usually has a length which is a multiple of 3 nucleotides, but does not contain a stop codon
in a given reading frame.
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
, a reading frame is a way of breaking a sequence of nucleotides in 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....
into three letter codons which can be translated
Translation (genetics)
In molecular biology and genetics, translation is the third stage of protein biosynthesis . In translation, messenger RNA produced by transcription is decoded by the ribosome to produce a specific amino acid chain, or polypeptide, that will later fold into an active protein...
in amino acids. There are 3 possible reading frames in an mRNA strand: each reading frame corresponding to starting at a different alignment. Double stranded 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...
has six different reading frames molecule due to the two strands from which transcription is possible - three of them reading forward and three of them reading backwards.
The existence of multiple reading frames leads to the possibility of overlapping gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s and there may be many of these in bacteria fungi parenthesis. Some viruses e.g. Hepatitis B virus
Hepatitis B virus
Hepatitis B is an infectious illness caused by hepatitis B virus which infects the liver of hominoidea, including humans, and causes an inflammation called hepatitis. Originally known as "serum hepatitis", the disease has caused epidemics in parts of Asia and Africa, and it is endemic in China...
and BYDV use several overlapping genes in different reading frames.
In rare cases a translating ribosome
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....
may shift from one frame to another, a translational frameshift
Translational frameshift
Translational frameshifting or ribosomal frameshifting refers to an alternate process of protein translation. A protein is translated from one end of the mRNA to the other, from the 5' to the 3' end. Normally a protein is translated from a template mRNA with consecutive blocks of 3 nucleotides...
. It is distinct from 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...
as the nucleotide sequence (DNA or RNA) is not altered only the frame in which it is read.
An open reading frame
Open reading frame
In molecular genetics, an open reading frame is a DNA sequence that does not contain a stop codon in a given reading frame.Normally, inserts which interrupt the reading frame of a subsequent region after the start codon cause frameshift mutation of the sequence and dislocate the sequences for stop...
(ORF) is a reading frame that contains a start codon
Start codon
The start codon is generally defined as the point, sequence, at which a ribosome begins to translate a sequence of RNA into amino acids.When an RNA transcript is "read" from the 5' carbon to the 3' carbon by the ribosome the start codon is the first codon on which the tRNA bound to Met,...
, and a subsequent region which usually has a length which is a multiple of 3 nucleotides, but does not contain a stop codon
Stop codon
In the genetic code, a stop codon is a nucleotide triplet within messenger RNA that signals a termination of translation. Proteins are based on polypeptides, which are unique sequences of amino acids. Most codons in messenger RNA correspond to the addition of an amino acid to a growing polypeptide...
in a given reading frame.