Transcription and RNA Processing
From DNA to RNA
Transcription Basics
Transcription copies a DNA template into RNA using RNA polymerase. The RNA sequence is complementary to the template strand and matches the coding strand except that replaces .
Promoters and Termination
Promoters are DNA sequences where transcription begins. Transcription factors help recruit RNA polymerase in eukaryotes, while termination signals end transcription.
RNA Types
RNA Is More Than a Messenger
Many RNAs are functional molecules that do not encode proteins but instead regulate or catalyze biological processes.
Which base appears in RNA instead of thymine?
RNA uses uracil in place of thymine.
Correct answer: Uracil
What is the purpose of the RNA 5' cap and poly(A) tail in eukaryotes?
These modifications improve mRNA lifespan and function.
Correct answer: They help protect mRNA and support export, stability, and translation.
What does RNA polymerase synthesize?
RNA polymerase uses DNA as a template to synthesize RNA.
Correct answer: RNA from DNA
RNA Splicing
In eukaryotes, introns are removed and exons are joined to form mature mRNA. Alternative splicing allows one gene to produce multiple transcript isoforms.
What is alternative splicing?
This expands protein diversity from a single gene.
Correct answer: A process in which different exon combinations are joined from the same pre-mRNA to produce multiple mRNAs.