Search results
Results from the WOW.Com Content Network
Two monosaccharides, such as glucose and fructose, can be joined together (to form saccharose) using dehydration synthesis. The new molecule, consisting of two monosaccharides, is called a disaccharide .
When transcription is arrested by the presence of a lesion in the transcribed strand of a gene, DNA repair proteins are recruited to the stalled RNA polymerase to initiate a process called transcription-coupled repair. [47] Central to this process is the general transcription factor TFIIH that has ATPase activity.
The process of transcription is a major source of DNA damage, due to the formation of single-strand DNA intermediates that are vulnerable to damage. [53] The regulation of transcription by processes using base excision repair and/or topoisomerases to cut and remodel the genome also increases the vulnerability of DNA to damage. [53]
During transcription, RNA polymerase makes a copy of a gene from the DNA to mRNA as needed. This process differs slightly in eukaryotes and prokaryotes. One notable difference is that prokaryotic RNA polymerase associates with DNA-processing enzymes during transcription so that processing can proceed during transcription.
Synthesis of RNA typically occurs in the cell nucleus and is usually catalyzed by an enzyme—RNA polymerase—using DNA as a template, a process known as transcription. Initiation of transcription begins with the binding of the enzyme to a promoter sequence in the DNA (usually found "upstream" of a gene).
Reverse transcription is the transfer of information from RNA to DNA (the reverse of normal transcription). This is known to occur in the case of retroviruses, such as HIV, as well as in eukaryotes, in the case of retrotransposons and telomere synthesis. It is the process by which genetic information from RNA gets transcribed into new DNA.
To initiate the transcription process in a cell's nucleus, DNA double helices are unwound and hydrogen bonds connecting compatible nucleic acids of DNA are broken to produce two unconnected single DNA strands. [1] One strand of the DNA template is used for transcription of the single-stranded primary transcript mRNA.
When a few (around three to six) monosaccharides are joined, it is called an oligosaccharide (oligo-meaning "few"). These molecules tend to be used as markers and signals, as well as having some other uses. [39] Many monosaccharides joined form a polysaccharide. They can be joined in one long linear chain, or they may be branched.