Question

Explain the process of transcription in prokaryotes. How is the process different in eukaryotes?

Answer 1

Hint: It is a process in both prokaryotes and eukaryotes. It results in formation of mRNA. It has three steps— initiation, elongation and termination.

Complete answer:
Transcription is defined as a process in which the information is copied from a DNA strand to a messenger mRNA. It involves three stages— initiation, elongation and termination. Messenger mRNA is formed by the enzyme RNA polymerase.
For eg. In case of E.coli the polymerase has five polypeptide subunits. These are called holoenzymes. Once the transcription completes the enzyme disassembles.
Transcription is a process that requires a double stranded DNA. This helps to partially unwind in the region of mRNA synthesis. This is known as the transcription bubble. The proteins and enzymes bind to the DNA sequence. This process is known as promoter. The sequencing of the promoter is essential to determine the process of transcription.
In the initial stage of transcription, RNA polymerase assembled holoenzyme assembles over the promoter. The a factor allows it to proceed over the DNA template to synthesise the mRNA molecules by adding variable nucleotide pairs.
The strand undergoing transcription is called a template strand. The mRNA formed is similar to the other single DNA strand. This other DNA strand is called a non template strand. This synthesis takes place in 5’ to 3’ direction.
In case of elongation the DNA double stranded helix is broken and new hydrogen bonds are formed. The RNA polymerase acts as a template and stabilises the DNA strand and the newly formed RNA strand.
Once the elongation completes termination comes into action. RNA polymerase dissociates from the DNA template. This leads to formation of mRNA.
The major difference between a prokaryote and eukaryote is — the nucleus in eukaryotes is membrane bound and in case of prokaryotes the nucleus lacks membrane.
In case of prokaryotes transcription occurs in cytoplasm and in case of eukaryotes the transcription occurs in the nucleus.

Note: Transcription is a process in both eukaryotes and prokaryotes. In case of eukaryotes it occurs in the nucleus. In case of prokaryotes it occurs in cytoplasm.