Transcription in Prokaryotes Flashcards
What is transcription?
This refers to the synthesis of RNA molecules using DNA strands as the templates so that the genetic information can be transferred from DNA to RNA.
DNA regions that can be transcribed into RNA are called
________.
structural genes
Transcription takes place in the nucleus. What are its three stages.
(1) Initiation
(2) Elongation
(3) Termination
(1) The template strand is the strand from which the RNA is transcribed. It is also termed as the ________/________/________ strand.
(2) The coding strand is the strand whose base sequence specifies the amino acid sequence of the encoded protein. Therefore, it is also known as the ________/________ strand.
(1) antisense, non-coding, minus
(2) sense, plus
List the subunits of the E. coli RNA polymerase and indicate the one that catalyses polymerization.
α (2), β, β’, ω
________, a therapeutic drug for tuberculosis treatment, can bind specifically to the β subunit of RNA-polymerase, and inhibit the RNA synthesis in prokaryotes.
Rifampicin
What regions does RNA polymerase recognize and slide to during promoter recognition in prokaryotic transcription?
RNA polymerase recognizes the TTGACA region (also known as the -35 region) and slides to the TATAAT region (Pribnow box or -10 region), where it opens the DNA duplex.
What is the first nucleotide on the RNA transcript, and which nucleotide is more commonly used?
The first nucleotide on the RNA transcript is always a purine triphosphate, with guanosine triphosphate (GTP) being more commonly used than adenosine triphosphate (ATP).
What happens to the sigma (σ) subunit of RNA polymerase after the first 3′,5′ phosphodiester bond is formed, and what does the core enzyme do next?
The sigma (σ) subunit of RNA polymerase falls off once the first 3′,5′ phosphodiester bond is formed, and the core enzyme then moves along the DNA template to enter the elongation phase of transcription.
In which direction does the RNA polymerase core enzyme move during the elongation phase?
The RNA polymerase core enzyme moves toward the 5′ end of the template strand.
How are nucleoside triphosphates (NTPs) added during the elongation phase of transcription?
Free NTPs are added sequentially to the 3′ -OH group of the nascent RNA strand.
What are terminators in the context of transcription termination?
Terminators are sequences where transcription stops.
State three similarities between transcription and replicaiton in Prokaryotes.
🧬 Both processes use DNA as the template.
🧬 Phosphodiester bonds are formed in both cases.
🧬 Both synthesis directions are from 5´ to 3’.
