Search results
Results from the WOW.Com Content Network
Gene structure is the organisation of specialised sequence elements within a gene. Genes contain most of the information necessary for living cells to survive and reproduce. [ 1 ] [ 2 ] In most organisms, genes are made of DNA, where the particular DNA sequence determines the function of the gene.
The structure of a eukaryotic protein-coding gene. Regulatory sequence controls when and where expression occurs for the protein coding region (red). Promoter and enhancer regions (yellow) regulate the transcription of the gene into a pre-mRNA which is modified to remove introns (light grey) and add a 5' cap and poly-A tail (dark grey).
In fact, many eukaryotic genes are regulated by releasing a block to transcription elongation called promoter-proximal pausing. [44] Pausing can influence chromatin structure at promoters to facilitate gene activity and lead to rapid or synchronous transcriptional responses when cells are exposed to an activation signal. [32]
The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA), and often a substantial fraction of junk DNA with no evident function. [2] [3] Almost all eukaryotes have mitochondria and a small mitochondrial genome. [2]
This level of chromatin structure is thought to be the form of heterochromatin, which contains mostly transcriptionally silent genes. Electron microscopy studies have demonstrated that the 30 nm fiber is highly dynamic such that it unfolds into a 10 nm fiber beads-on-a-string structure when transversed by an RNA polymerase engaged in transcription.
Introns are found in the genes of most eukaryotes and many eukaryotic viruses and they can be located in both protein-coding genes and genes that function as RNA (noncoding genes). There are four main types of introns: tRNA introns, group I introns, group II introns, and spliceosomal introns (see below).
A core set of genes that function in meiosis is present in both Trichomonas vaginalis and Giardia intestinalis, two organisms previously thought to be asexual. [ 51 ] [ 52 ] Since these two species are descendants of lineages that diverged early from the eukaryotic evolutionary tree, core meiotic genes, and hence sex, were likely present in the ...
The discovery of gene regulatory RNAs has led to attempts to develop drugs made of RNA, such as siRNA, to silence genes. [83] Adding to the Nobel prizes for research on RNA, in 2009 it was awarded for the elucidation of the atomic structure of the ribosome to Venki Ramakrishnan , Thomas A. Steitz , and Ada Yonath .