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Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a speciation event (orthologs), or a duplication event (paralogs), or else a horizontal (or lateral) gene ...
For example, in an aligned DNA sequence matrix, all of the A, G, C, T or implied gaps at a given nucleotide site are homologous in this way. Character state identity is the hypothesis that the particular condition in two or more taxa is "the same" as far as our character coding scheme is concerned.
NHEJ is a DNA repair mechanism which, unlike homologous recombination, does not require a long homologous sequence to guide repair. Whether homologous recombination or NHEJ is used to repair double-strand breaks is largely determined by the phase of cell cycle. Homologous recombination repairs DNA before the cell enters mitosis (M phase).
Gene conversion is the process by which one DNA sequence replaces a homologous sequence such that the sequences become identical after the conversion. [1] Gene conversion can be either allelic, meaning that one allele of the same gene replaces another allele, or ectopic, meaning that one paralogous DNA sequence converts another.
The distance between each gene in the gene cluster can vary. The DNA found between each repeated gene in the gene cluster is non-conserved. [10] Portions of the DNA sequence of a gene is found to be identical in genes contained in a gene cluster. [5] Gene conversion is the only method in which gene clusters may become homogenized. Although the ...
The concept of concerted evolution is a molecular process which leads to the homogenization of DNA sequences. [1] As shown from the diagram on the right, as each organism evolves, it creates a species that is more closely related to their genes than anyone else in their species. This is demonstrated by the different colors of circles.
[2] [3] The mRNA sequence is determined by the sequence of genomic DNA. [4] In this context, the standard genetic code is referred to as translation table 1. [3] It can also be represented in a DNA codon table. The DNA codons in such tables occur on the sense DNA strand and are arranged in a 5 ′-to-3 ′ direction.
Non-allelic homologous recombination (NAHR) is a form of homologous recombination that occurs between two lengths of DNA that have high sequence similarity, but are not alleles. [ 1 ] [ 2 ] [ 3 ] It usually occurs between sequences of DNA that have been previously duplicated through evolution, and therefore have low copy repeats (LCRs).