Transcription Flashcards
Helicase and topoisomerase:
unwind the DNA double helix
RNA polymerase 2
binds to the TATA box within the promoter region of the gene (25 base pairs upstream from first transcribed base)
hnRNA
synthesized from the DNA template (antisense) strand
Posttranscritional modifications include:
- a 7 - methylguanylate triphosphate cap is aded to the 5’ end
- a polyadenosyl (PolyA) tail is added to the 3’ end
Splicing
is done by snRNA and snRNPs in the spliceosome; introns are removed in a lariat structure, and eons are ligated together
Prokaryotic cells can increase WHAT?
the variability of gene products from one transcript through POLYCISTRONIC GENES (starting transcription in different sites within the gene leads to different gene products)
Eukaryotic cells can increase WHAT?
the variability of gene products through alternative splicing (combining different eons in a modular fashion to acquire different gene products)
generating a protein is done where?
in the cytoplasm
transcription
the creation of mRNA from a DNA template
RNA polymerase I
located in the nucleus and synthesizes rRNA
RNA polymerase II
located in the nucleus and synthesizes horn (preprocessed mRNA) and some small nuclear RNA (snRNA)
RNA polymerase III
located in the nucleus and synthesizes tRNA and some rRNA
In what direction does the RNA polymerase travel?
3’ –> 5’
RNA polymerase
does not proofread its work
coding strand (sense strand)
not used as a template during transcription
complementary to the template strand