Medical Physiology - Regulation of Gene Function and Cell Biochemical Activity

Medical Physiology - Regulation of Gene Function and Cell Biochemical Activity
By determining the relative percentage of the many kinds of enzymes and structural proteins that are generated, the genes regulate each cell's activity. The entire process, from the nucleus' transcription of the genetic code to the cytoplasm's production of proteins, is governed by gene expression regulation. Gene expression is regulated by the promoter. The transcription of DNA into RNA, which is governed by regulatory elements in a gene promoter, is the first step in the production of cellular proteins. The basal promoter of eukaryotes, including mammals, is made up of the TATA box, a seven-base sequence (TATAAAA) that serves as the binding site for the TATA-binding protein (TBP), and a number of other significant transcription factors that are referred to as the transcription factor IID complex. To help with the transcription of DNA into RNA, transcription factor IIB binds to both DNA and RNA polymerase 2 in this area in addition to the transcription factor IID complex.

All protein-coding genes contain this basal promoter, which the polymerase must bind to in order to start moving down the DNA strand and synthesizing RNA. More upstream from the transcription start site, the upstream promoter has many binding sites for either positive or negative transcription factors that can influence transcription by interacting with proteins attached to the basal promoter.
Diverse genes have diverse transcription factor binding locations in the upstream promoter, which results in distinct gene expression patterns in various tissues. Enhancers, which are areas of DNA that have the ability to bind transcription factors, also have an impact on gene transcription in eukaryotes. Enhancers may be found on a separate chromosome or even a considerable distance from the gene they affect. However, when DNA is coiled in the nucleus, enhancers may be very close to their target gene even if they may be positioned far away. The human genome is thought to have 110,000 gene enhancer sequences. Negative feedback from the cell product controls the promoter. The promoter that is in charge of its synthesis is inhibited by negative feedback when the cell produces a crucial quantity of the material. A regulatory activator protein can disrupt the connection formed by a regulatory repressor protein at the repressor operator, or a regulatory repressor protein can cause this inhibition. The promoter is suppressed in both situations. Other methods that the promoter can use to regulate transcription include the following: 1. Transcription factors found elsewhere in the genome may regulate a promoter. 2. In certain cases, a single regulatory protein can operate as both an activator and a repressor for distinct promoters, enabling the regulation of several promoters simultaneously by the same regulatory protein. 3. The chromosomes are particular structural units that contain the nuclear DNA.
DNA is looped around tiny proteins called histones inside each chromosome, and these proteins hold the DNA firmly together in a compacted condition. The DNA cannot produce RNA while it is in this compacted state. However, there are a number of processes that can decompact specific chromosomal regions, enabling RNA transcription. Even so, the actual rate of transcription by the chromosome's promoter is regulated by certain transcriptor factors.