Transcription & RNA processing Flashcards
Where is DNA converted to RNA
In the nucleus DNA is converted to RNA
Why must genetic code be copied and transferred out of nucleus
Because the DNA found in nucleus is too big to move out (carried from DNA in nucleus to ribosomes in cytoplasm)
Define proteome
All protein in a cell
Enzymes that synthesise RNA from DNA are called _____
RNA polymerases (Pol II)
RNA is synthesised from which strand of DNA and in what direction
RNA is synthesised from the TEMPLATE (antisense) DNA strand which runs 3’—5’
In which direction does RNA polymerase synthesise complementary RNA
RNA is synthesised 5’—3’ as we synthesise RNA from the template strand so complementary base pairing means it’s the right way round 5’—3’ when it’s made (in RNA U instead of T)
What are the 5 steps of mRNA synthesis
INITIATION: polymerase binds to gene
ELONGATION: polymerase transcribes gene
TERMINATION: polymerase stops transcribin gene
PROCESSING: pre mRNA—> mature mRNA is formed
EXPORT: mRNA leaves nucleus through nuclear pore to be translated
What region initiates transcription that the RNA polymerase binds to at beginning
RNA polymerase binds close to PROMOTER REGION to initiate transcription
The promoter acts as a template for assembly of ______. This brings Pol II to gene. Once bound, polymerase can transcribe
The promoter acts as a template for assembly of PREINITIATION COMPLEX. This brings Pol II to gene. Once bound, polymerase can transcribe
What are the polymerase positioning elements
• TATA box= initiator
• upstream + downstream elements that bind +ve & -vely acting transcription factors (enhancers + silencers)
What happens in elongation stage of transcription
RNA polymerase synthesises complementary RNA in 5’—3’ direction using NTPs ( ribonucleoside triphosphates)
List difference between RNA & DNA
- different pentose sugar: deoxyribose in DNA, ribose in RNA
*DNA is double stranded; RNA is single stranded
*DNA has Thymine (T), RNA has Uracil (U)
How many bonds between
Thymine and Adenine
Uracil and Adenine
2 bonds between T & A
2 bonds between U & A
How many bonds between Guanine and Cytosine
3 bonds between G & C
What type of linkages form backbone of both DNA & RNA
PHOSPHODIESTER linkages form backbone of both DNA & RNA