Transcription
MCAT glossary · Biological & Biochemical Foundations of Living Systems
Definition
Synthesis of RNA from a DNA template by RNA polymerase, reading 3'→5' and synthesizing 5'→3'.
Transcription in plain English
Transcription is the step where your cell makes a working copy of one gene's instructions. Think of DNA as a permanent master cookbook locked in the kitchen safe — you don't drag the whole book to the stove, so a machine called RNA polymerase copies just the one recipe you need onto a disposable note called RNA. The polymerase slides along one DNA strand reading it back-to-front (the 3'to5' direction, just a way of labeling the two ends of the strand) and builds the new RNA in the opposite 5'to3' order. That RNA copy then carries the recipe out to be used, leaving the original DNA safe and unchanged.
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