Transcription Flashcards
transcription
same language
DNA to mRNA
translation
different language
mRNA to protein
what is similar between transcription and translation?
both use topoisomerase to unwind
helicase unzip double stranded DNA
template strand
also known as the antisense strand
complementary and antiparallel to mRNA
mRNA
reads 5’ to 3’
Coding prime
sense strand
DNA identical to RNA except T for U
in order to start transcription, what needs to happen
initiation
RNA polymerase II locates promoter region –> TATA box
transcription factors help w binding and location
no RNA primer required
the different kind of RNA polymerase
RNA polymerase I: in nucleolus, synthesizes most rRNA
RNA polymerase II: in nucleus, synthesizes hnRNA (pre-mRNA)
RNA polymerase III: in nucleus, synthesizes tTNA and some rRNA
after initiation, what happens
elongation
synthesis is always 5’ to 3’
primary transcript to hnRNA
the presence of which base indicates DNA and NOT RNA
T
hnRNA
in the nucleus
has a 5’ and 3’
posttranscriptional processing
5’ cap: protects from degradation, recognized by ribosome to prime
poly-A tail: protection against degradation, longer tail= better protection
splicing is done by the spliceosome, consists of small nuclear RNA, remove introns
transporto to cytoplasm for translation
to turn into mRNA
untranslated regions exist but translation initiates/stops at start(AUG)/stop(UAG,UAA,UGA) codon
introns stay IN the nucleus
EXtrons exit the nucleus
When does DNA leave the nucleus in transcription
once it has become mRNA, after it has done DNA to hnRNA and posttranscriptional processing
