How do eukaryotes produce mRNA that they can use for transla

How do eukaryotes produce mRNA that they can use for translation?

Solution

11. The two important steps in protein synthesis are “transcription and translation.” During protein synthesis, mRNA is synthesised under the direction of DNA. The message carried by the DNA is read by the mRNA, this process is called “transcription,” it takes place in the nucleus.

Gene transcription is the first step in protein synthesis. A group of transcription factors assemble at the promoter region of DNA, and bind to TATA box to change its shape. This event exposes the binding sites of other transcription factors. After several of these events, RNA polymerase binds.

The binding of RNA polymerase to the promoter site starts the process of transcription. There are three different classes of RNA polymerases that bind to different promoter sites and transcribe different parts of genome. The terminator present at another end of the genome signals the completion of transcription, thus terminating the programme.

6b). In case of eukaryotes, the pre-mRNA must undergo modifications, before making it ready for translation. These modifications include, addition of 5’cap, poly A tail, removal of introns.

Addition of 5’cap: During this step, the 7-methylguanosine cap is added to the 5’end of the pre-mRNA, which protects the mRNA from degradation and allow the binding of ribosomes. This process needs the mRNA guanylyltransferase enzyme (to add GTP to the terminal bisphosphate).

Addition of Poly A tail: A poly A tail is added to the 3’ end of the pre-mRNA after the completion of elongation. This protects the mRNA from degradation and facilitate the mature mRNA export to the cytoplasm. Removal of introns: Before the export of mRNA to the cytoplasm, the introns are removed from the pre-mRNA.