Question

The process of formation of mRNA from DNA is known as
A. Transformation
B. Translation
C. Transcription
D. Translocation
E. Replication

Answer 1

Hint: Central dogma is a process in which instructions in DNA are converted into a final product. One of the processes involves the formation of mRNA from DNA that involves the transfer of genetic material from one strain to another without any physical contact.

Complete Answer:
- This process of synthesis of RNA from DNA is known as transcription. Transcription occurs when there is a need for a particular gene product at a specific time or in a specific tissue.
- Only one strand of DNA is copied for the formation of RNA, called the template strand. The RNA molecules produced are single-stranded messenger RNAs (mRNAs). The DNA strand that corresponds to the mRNA is called the coding or sense strand. In eukaryotes, the initial product of transcription is called a pre-mRNA.
- Pre-mRNA is edited by the splicing process before the mature mRNA is produced and becomes ready for translation by the ribosome.
- Transcription is carried out by an enzyme called RNA polymerase and several accessory proteins called transcription factors.
- Small segments of DNA are transcribed into RNA by the enzyme RNA polymerase. The promoter region signifies the start of the gene. In this region, the two strands of DNA become separated and RNA polymerase starts copying from a specific point on one strand of the DNA using a special type of sugar-containing nucleoside called ribonucleoside 5’-triphosphate to begin the growing chain.
- Additional ribonucleoside triphosphates are used as the substrate, and, by cleavage of their high-energy phosphate bond, ribonucleoside monophosphates are incorporated into the growing RNA chain.
- The bases are added according to the complementary base pairing rules of DNA. For example, a C (cytosine) in DNA pairs with a G (guanine) in RNA. Similarly, a G in DNA is copied into a C in RNA, a T (thymine) into an A (adenine), and an A into a U (uracil; RNA contains U in place of the T of DNA). Synthesis continues until a termination point is reached and the signal is given for the RNA molecule to be released. RNA polymerase drops off the DNA.

Hence, the correct option is C, “Transcription”.

Note: Gene transcription occurs in both eukaryotic and prokaryotic cells. Unlike prokaryotic RNA polymerase that initiates the transcription of all different types of RNA, RNA polymerase in eukaryotes (including humans) comes in three variations, each translating a different type of gene. Eukaryotic transcription occurs within the nucleus where DNA is packaged into nucleosomes and higher-order chromatin structures. The eukaryotic transcription is a bit more complex process than the prokaryotic one because of the complex genome in eukaryotes.