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Riboswitch-mediated folding sequesters the ribosome-binding site, thereby inhibiting translation. The riboswitch is a ribozyme that cleaves itself in the presence of sufficient concentrations of its metabolite. Riboswitch alternate structures affect the splicing of the pre-mRNA.
The TPP riboswitch, also known as the THI element and Thi-box riboswitch, is a highly conserved RNA secondary structure. It serves as a riboswitch [1][2] that binds thiamine pyrophosphate (TPP) directly and modulates gene expression through a variety of mechanisms in archaea, bacteria and eukaryotes. [3][4][5] TPP is the active form of thiamine ...
The 3–4 structure is a transcription termination sequence, once it forms RNA polymerase will disassociate from the DNA and transcription of the structural genes of the operon will not occur. Part of the leader transcript codes for a short polypeptide of 14 amino acids, termed the leader peptide.
A typical operon. In genetics, an operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter. [1] The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo splicing to create monocistronic mRNAs that are translated separately, i.e. several strands of mRNA that each encode a single gene product.
The riboswitch functions by directly sensing a physiological signal. [10] Next, a specific uncharged tRNA binds to a riboswitch element in the transcript, and a structural change occurs in the transcript that promotes expression of the downstream coding sequence. [2] [10] The specifier sequence is the first recognition sequence in the leader. [7]
Histone acetylation and deacetylation. The crystal structure of the nucleosome core particle consisting of H2A , H2B , H3 and H4 core histones, and DNA. The view is from the top through the superhelical axis. Histone acetylation and deacetylation are the processes by which the lysine residues within the N-terminal tail protruding from the ...
The polypeptide chain then folds and is post-translationally modified. Protein biosynthesis (or protein synthesis) is a core biological process, occurring inside cells, balancing the loss of cellular proteins (via degradation or export) through the production of new proteins. Proteins perform a number of critical functions as enzymes ...
Several cell function specific transcription factor proteins (in 2018 Lambert et al. indicated there were about 1,600 transcription factors in a human cell [8]) generally bind to specific motifs on an enhancer [9] and a small combination of these enhancer-bound transcription factors, when brought close to a promoter by a DNA loop, govern the ...