L16 Flashcards
What is gene expression
Process by which information from a gene is used in the synthesis of a function gene product eg protein or tRNA
what is a gene?
defined region (sequen) of DNA that produces a type of RNA molecules that has some function
the gene can contain sequences responsible for:
Synthesis, regulation of synthesis and processing of RNA
What enzyme is responsible for synthesising mRNA?
RNA polymerase, by forming phosphodiester bonds between ribonucleotides
Which direction is the coding strand?
5’-3’
Which direction is template strand?
3’-5’
Which strand is mRNA made from?
Template strand
What are the 3 stages of transcription?
-initiation
-elongation
-termination
What happens in initiation?
-Transcription factors bind onto TATA box and promoter
-RNA pol II, binds and forms transcription initiation complex
-Two DNA strands sperate and RNA pol II begins mRNA synthesis without primer
What happens in elongation?
-RNA pol II uses template strand, and inserts complementary RNA nucleotides in 5’-3’ directions
What is splicing?
Where untranslated introns in mRNA are cut out
What is a coding sequence?
Portion of a genes DNA that is translated into a protein
What is a promoter?
DNA segment recognised by RNA pol to initiate transcription
What are UTRs? (untranslated regions
Regions that are transcribed but not translated
-5’ G cap
-3’ poly A tail
What is the function of G cap and Poly A tail?
-Prevents mRNA degradation
Where does transcription occur in prokaryotes?
in cytoplasm
Where does transcription occur in eukaryotes?
in Nucleus
