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Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. In virology, the term transcription is used when referring to mRNA synthesis from a viral RNA ...
A second version of the central dogma is popular but incorrect. This is the simplistic DNA → RNA → protein pathway published by James Watson in the first edition of The Molecular Biology of the Gene (1965). Watson's version differs from Crick's because Watson describes a two-step (DNA → RNA and RNA → protein) process as the central ...
Double stranded DNA that enters from the front of the enzyme is unzipped to avail the template strand for RNA synthesis. For every DNA base pair separated by the advancing polymerase, one hybrid RNA:DNA base pair is immediately formed. DNA strands and nascent RNA chain exit from separate channels; the two DNA strands reunite at the trailing end ...
Protein synthesis is a very similar process for both prokaryotes and eukaryotes but there are some distinct differences. [1] Protein synthesis can be divided broadly into two phases: transcription and translation. During transcription, a section of DNA encoding a protein, known as a gene, is converted into a molecule called messenger RNA (mRNA).
For transcription to take place, the enzyme that synthesizes RNA, known as RNA polymerase, must attach to the DNA near a gene.Promoters contain specific DNA sequences such as response elements that provide a secure initial binding site for RNA polymerase and for proteins called transcription factors that recruit RNA polymerase.
RNAP produces RNA that, functionally, is either for protein coding, i.e. messenger RNA (mRNA); or non-coding (so-called "RNA genes"). Examples of four functional types of RNA genes are: Transfer RNA (tRNA) Transfers specific amino acids to growing polypeptide chains at the ribosomal site of protein synthesis during translation; Ribosomal RNA (rRNA)
Any step of gene expression may be modulated, from the DNA-RNA transcription step to post-translational modification of a protein. The stability of the final gene product, whether it is RNA or protein, also contributes to the expression level of the gene—an unstable product results in a low expression level.
Micrograph of gene transcription of ribosomal RNA illustrating the growing primary transcripts. A primary transcript is the single-stranded ribonucleic acid product synthesized by transcription of DNA, and processed to yield various mature RNA products such as mRNAs, tRNAs, and rRNAs.