Transcription and gene expression Flashcards
Where does RNA Polymerase start to make a copy of RNA?
The promoter, which is located at the 5’ end.
What are the three stages of transcription?
- Initiation
- Elongation
- Termination
What is the initiation stage?
When the RNA polymerase binds to the DNA at the promoter region and the double helix unwinds.
What is the elongation stage?
When the mRNA becomes longer as nucleotides are added to the 3’ OH group
What is the termination stage?
When the mRNA synthesis is complete and the complex of DNA, RNA polymerase, and mRNA disassembles.
What is the sense strand?
The DNA strand that is not being transcribed.
What is an antisense strand?
The DNA strand that is being transcribed.
What is splicing?
The removal of introns and joining the exons to form mature mRNA.
What is the function of nucleosomes?
It acts as an enzyme to remove the introns and join the exons together, to form mature mRNA.
What is the process of post-transcriptional modification of mRNA?
Transcription generates pre-mRNA, which is modified by splicing out the intron sequences, adding a cap and a poly-A tail.
What unwinds the DNA strand in transcription?
RNA polymerase, acts as an enzyme and breaks the hydrogen bonds
What is the function of the cap and poly-A tail?
To protect the mRNA from degradation in the cytoplasm.
