The majority of genes have the necessary instructions to produce the functional molecules known as proteins. Here, let’s learn the processes by which genes are converted to proteins.
Table of Contents
Gene to Protein
Genes are DNA sequences that control the synthesis of proteins and serve as bridges between phenotype and genotype. The amino acid sequences that make up proteins are specified by the protein-coding genes. Proteins, in turn, are in charge of directing almost all cellular processes. All cells maintain their genetic information through the three primary processes:
- Replication
- Transcription
- Translation
Replication
The base of biological inheritance is replication. The DNA of a cell is copied in this process. A single parental double-stranded DNA molecule is copied by the enzyme DNA polymerase into two daughter double-stranded DNA molecules. In subsequent steps, these DNA fragments are utilised to create RNA.
Transcription
A single DNA strand serves as a template for the creation of a complementary strand of RNA during transcription.
- The attachment of the RNA polymerase enzyme to a DNA molecule is the initial step in transcription. The promoters, which are specialised sequences of 20 to 200 bases where various interactions take place, are the locations where binding takes place.
- The promoter DNA is bound by RNA polymerase and one or more general transcription factors. RNA polymerase synthesises new RNA nucleotides. These are complementary to the nucleotides present in one of the DNA strands.
- The freshly formed RNA strand is released when the RNA-DNA helix’s hydrogen bonds are disintegrated. The RNA might undergo additional processing like splicing, capping and polyadenylation.
- A messenger RNA (mRNA) molecule is thus created during the transcription of a gene.
Also Check: What Is Translation in Biology?
Translation
In the process of translation, mRNA or messenger RNA is decoded outside the nucleus in a ribosome to create a particular polypeptide or amino acid chain. The polypeptide chain undergoes further folding into secondary, tertiary and quaternary structures and carries out its specific tasks within the cell. This process happens in the following sequential steps:
- Initiation – The ribosome forms a protective shell around the target mRNA. Now, the first tRNA molecule is joined at the start codon.
- Elongation – The last accepted tRNA by the smaller subunit of ribosome transmits the amino acid it contains to the larger ribosomal subunit, which binds it to one of the previously admitted tRNAs. Following this, the ribosome translocates to the subsequent mRNA codon to complete the process and produce a polypeptide chain.
- Termination – The ribosome releases the polypeptide on reaching the stop codon. The next mRNA to be translated is taken up by the ribosomal complex, which is still intact.
Thus the genetic information is transferred from DNA(gene) to RNA and to Protein, which is a functional product. This is known as the central dogma.
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