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Transcription and Translation

Terms in this set (57)

Transcription
synthesis of RNA from genetic info contained in DNA
What is a template for mRNA in transcription?
one of the strands for DNA, which acts as an intermediate that carries the genetic message from the DNA to be carried out in the protein
pre-mRNA
Must be enzymatically modified with the addition of a guanine cap and a poly-A tail. This occurs in the nucleus. Final mRNA is able to leave the nucleus through a nuclear pore and travel to the cytoplasm
What does transcription require?
a DNA template, an enzyme called RNA polymerase, and a nucleoside triphosphate (including ATP, GTP, CTP, and UTP)
What are the three main stages of transcription
Initiation
Elongation
Termination
Initiation- transcription
RNA polymerase is the enzyme that catalyzes the synthesis of mRNA from DNA. It binds to a sequence on the template strand called the promoter sequence and starts to unwind the DNA.
Elongation-transcription
Next, RNA polymerase connects nucleotides that base-pair with the template strand nucleotides, forming the RNA. Like DNA polymerase, RNA polymerase adds nucleotides from 5' to 3'-that is, it can only add nucleotides to the 3' end.
What does it mean that DNA and RNA are processive?
meaning it can catalyze the step-by-step addition of hundreds of nucleotides each time it binds to DNA. Unlike DNA polymerase, however, RNA polymerase does not require a primer to be laid down before initiation starts
Termination-transcription
Transcription stops when RNA polymerase reaches the terminator sequence. RNA than stops transcription and disengages from the DNA. The mechanisms for termination can vary.
Is protein synthesis the same in prokaryotes and eukaryotes?
No. Specifically, transcription and translation are paired in prokaryotes but not eukaryotes
Transcription in prokaryotes
the messenger RNA that is produced through transcription is immediately translated into protein without further processing.
Transcription in eukaryotes
Transcription occurs in the nucleus, results in pre-mRNA. This is transported out of the nucleus and travels to the ribosomes, either in the cytosol or on a membrane. Translation occurs on the ribosomes.
Eukaryotic transcription involves
enhancers, silencers, transcription factors, and mRNA modifications and chromatin remodeling
In prokaryotic transcription, what can happen at the same time?
Translation and transcription
7-methylguanosine cap (5' cap or a G cap)
Added to the 5' end of the pre-mRNA. This protects the transcript from degradation by exonucleases and serves as a recognition signal for ribosomes. The guanosine cap ensures that the mRNA remains stable as it is transported our of the nucleus and white it undergoes translation during protein synthesis.
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