Gene expression: Transcription Flashcards
What is the ‘central dogma of molecular biology’
DNA(information) is transcribed to RNA(messenger) which goes through translation to produce proteins(worker)
What processes does the central dogma include
DNA replication, RNA synthesis and RNA to DNA
How is information content of a gene expessed
Gene expression - information from a gene used in synthesis of functional gene products like proteins and non-coding RNA
What are genes responsible for
regulation and synthesis of RNA, production of RNA and further processing of RNA
What are the three steps of transcription
Initiation, elongation and termination
What is transcription
DNA dependant RNA synthesis.
What are the two strands used in transcription
Coding strand - contains information for cell use (5’ to 3’)
Non-coding strand -Used as template for synthesis (3’ to 5’)
What enzyme is used
RNA polymerase synthesises mRNA (catalyses formation of phosphodiester bonds between ribonucleotides)
Describe initiation
First transcription factors and RNA Pol bind to promoter region forming a transcription initiation complex together. The two strands then separate and mRNA synthesis starts without need of a primer.
Why does RNA polymerase not need a primer
It has an internal 3 prime
What is the promoter region
An AT rich region that allows easier separation of the strands (A and T only held together by 2 H bonds)
Describe elongation
Template strand is then used to insert complimentary RNA nucleotides in 5’ to 3’ direction.
What nucleotides are used in RNA synthesis
G,C,U,T
What is a trait of termination
It differs in eukaryotes and prokaryotes
What are introns
Non-coding regions
What is the structure and function of introns
They break up coding regions (in eukaryotes) and regulate protein synthesis
What does the 5’ G cap do
Prevents mRNA degradation,
Promotes inserting on introns
Provides a binding site for the small ribosomal subunit
What does the poly-A-tail do
Prevents mRNA degradation and facilitates export of the mRNA from nucleus to cytoplasm
Where does the 5’Gcap and poly-A-tail attach
UTR’s facilitates the addition of these. It also contains regulatory elements that influence gene expression
