RNA Processing - Unit 3 Slide 11

How is transcription regulated?

Both how frequently and how tightly transcription factors and RNA polymerase bind to the promoter

Where does transcription and translation occur in Eukaryotes?

Transcription occurs in the nucleus while translation occurs in the cytoplasm.

Where does transcription and translation occur in Bacteria?

Transcription and translation occur simultaneously in the cytoplasm.

Is mRNA processed in bacteria?

No, mRNA is not processed in bacteria as it is in eukaryotes; it is translated directly after transcription.

What changes are made to mRNA in Eukaryotes before leaving the nucleus?

the primary transcript (pre-mRNA) is modified by adding a 5’ cap, a 3’ poly-A tail and splicing out the introns while linking exons together

What is primary transcript?

pre-mRNA that is newly transcribed without applying any modificiations

5’ cap

7-methylguanosine that is linked to the 5’ end of mRNA with its 5’ phosphate. It is used to help bind the ribosome to mRNA to initiate translation

3’ polyA tail

Protects the ends of mRNA from degration by enzymes by adding around 250 As at the 3’ end of mRNA

Exons

Regions that code for amino acids

Introns

Regions that do not code for amino acids and are spliced off in eukaryotes during mRNA processing

Spliceosomes

ribonucleoprotein complexes that recognize, and split splice junctions while also joining exons together

Splice variants

variations of mRNA based on what exons are spliced out