What is transcription of DNA?

Transcription is the process by which the genetic information encoded in DNA is copied into a molecule called RNA (ribonucleic acid). It plays a crucial role in gene expression, as RNA serves as a template for protein synthesis.

To understand transcription, you need to know a bit about the structure of DNA. DNA consists of two complementary strands twisted together in the shape of a double helix. Each strand is made up of a series of building blocks called nucleotides, which include a sugar molecule (deoxyribose), a phosphate group, and one of four nitrogenous bases (adenine, cytosine, guanine, or thymine).

During transcription, only one of the DNA strands, known as the template strand or antisense strand, is used as a template to synthesize RNA. An enzyme called RNA polymerase recognizes and binds to a specific region on the DNA called the promoter. This signals the beginning of a gene, the segment of DNA that contains the instructions for making a specific protein.

As the RNA polymerase moves along the DNA template strand, it unwinds the two DNA strands, exposing the nucleotides. Following the base pairing rules, the RNA polymerase adds complementary RNA nucleotides to the growing RNA chain. However, there is a slight difference in the RNA nucleotides. Instead of thymine, RNA contains a base called uracil (U). So, adenine (A) in DNA pairs with uracil (U) in RNA.

The process of RNA synthesis continues until the RNA polymerase reaches a specific sequence of bases called the terminator. At this point, the RNA molecule is released from the DNA template, and the DNA strands rejoin. The newly synthesized RNA molecule, known as primary transcript or pre-mRNA, undergoes further modifications (splicing, capping, and tailing) before it can be translated into a protein.

In summary, transcription is the process by which RNA is synthesized using DNA as a template. It involves RNA polymerase binding to the promoter region, unwinding the DNA double helix, adding complementary RNA nucleotides, and finally releasing the RNA molecule.