explain how rna is made during transcription
To understand how RNA is made during transcription, let's first discuss the basics of transcription. Transcription is a process that occurs in the cell nucleus, where DNA (deoxyribonucleic acid) is used as a template to synthesize RNA (ribonucleic acid).
Here are the steps involved in transcription:
1. Initiation: Transcription begins when an enzyme called RNA polymerase binds to a specific region on the DNA molecule, called the promoter region. The promoter acts as a signal for RNA polymerase to start transcription.
2. Elongation: Once RNA polymerase is bound to the promoter, it unwinds and separates the DNA double helix into two strands. One of the DNA strands, known as the template strand, serves as a template for synthesizing the RNA molecule. RNA polymerase reads the nucleotide sequence of the template strand and forms complementary base pairs with free RNA nucleotides.
3. Base pairing: During elongation, RNA polymerase adds RNA nucleotides that are complementary to the DNA template strand by forming base pairs. Adenine (A) pairs with uracil (U) in RNA, cytosine (C) pairs with guanine (G), and thymine (T) in DNA pairs with adenine (A).
4. Termination: Transcription continues along the template strand until it reaches a specific termination signal on the DNA molecule. This signal causes RNA polymerase to detach from the DNA template and release the newly synthesized RNA molecule.
The resulting RNA molecule is called the primary transcript or pre-mRNA. It undergoes further processing, including the removal of non-coding regions called introns and the joining of coding regions called exons, to form a mature RNA molecule. This mature RNA, such as messenger RNA (mRNA), transfer RNA (tRNA), or ribosomal RNA (rRNA), can then be used for different cellular functions.
In summary, during transcription, RNA polymerase binds to the DNA template strand and synthesizes an RNA molecule by adding complementary RNA nucleotides. This process occurs through base pairing, where A pairs with U, C pairs with G, and T pairs with A in DNA. The resulting RNA molecule undergoes further processing to become functional RNA in the cell.