Complementary Base Pairing: RNA synthesis follows strict rules where Adenine (A) pairs with Uracil (U), and Cytosine (C) pairs with Guanine (G). Note that RNA uses Uracil instead of the Thymine (T) found in DNA.
Directionality: RNA Polymerase moves along the DNA template strand in a direction, which results in the new RNA strand being synthesized in the direction.
Strand Asymmetry: Only one of the two DNA strands, known as the template strand, is transcribed for a specific gene; the other is the coding strand, which matches the RNA sequence (except for T/U).
In eukaryotes, the initial transcript is called pre-mRNA, which contains both coding regions (exons) and non-coding regions (introns).
Splicing is the critical process where introns are removed and exons are joined together by a spliceosome to create a functional, mature mRNA molecule.
Alternative Splicing allows a single gene to code for multiple different proteins by joining different combinations of exons together, increasing genetic diversity.
The T vs. U Rule: When converting a DNA sequence to RNA, always replace Thymine with Uracil. A common mistake is leaving 'T' in an RNA sequence.
Strand Identification: Remember that the mRNA sequence is identical to the coding strand (with U instead of T) and complementary to the template strand.
Direction Check: Always verify the and ends. RNA is always built . If an exam gives a DNA template, you must read it backward to synthesize the RNA.
Enzyme Precision: Do not confuse RNA Polymerase (transcription) with DNA Polymerase (replication). RNA Polymerase does not require a primer to start synthesis.
