theme 2- CB12 Gene Transciption, messenger RNA synthesis. processing and regulation Flashcards
What is the central dogma of molecular biology?
description of the 2 stages that transfers genetic information from DNA to RNA then proteins
Why have mRNA synthesis
and translation?
- Increases protein synthesis efficiency
• Many RNA molecules can be synthesised
from the same gene (which the cell usually has one copy of)
• This can be done simultaneously and rapidly
• Many protein molecules can be made from
the same RNA molecule - Facilitates regulation
• Regulation of mRNA synthesis and function is
a key point of regulation
What allows lots of protein from gene A to be produced but little protein from gene B?
Differential regulation of gene expression
What are the stages of transcription?
1) Initiation-this is a key point of regulation
2) Binding of RNA polymerase to the sequence of DNA
near a gene called a promoter
3)Base pairing between RNA nucleoside triphosphate with template stand of DNA.
4) RNA is formed through condensation reactions forming new phosphodiester bonds between nucleotides using energy from the breakage of
high energy phosphate bond in nucleoside
triphosphates
How is transcription rapid?
• Many RNA molecules can be synthesised
simultaneously on the same DNA template
Which strand of DNA is RNA identical to?
RNA is synthesised on the template strand
but is identical to the coding strand of DNA
Which direction does RNA polymerase move in:
3’ to 5’ on the template strand
A)How many RNA polymerase are there in... B) where does it start in.. C)what is required for initiation.. D) Describe the RNA formed: 1) prokaryotes 2) eukaryotes
a) 1) 1 2)3
b) 1)2) promoter
C) 1) No extra requirements 2) Transcription factors
required
D)1) May contain transcript of multiple, functionally related genes
2)Contains transcript of
single gene
Why is RNA processing not required in prok.?
no introns
What processing of the mRNA occurs in the nucleus:
Adding of 5’ cap (a nucleotide derivative) and 3’ polyadenyl tail • Increase stability • Facilitates transport to cytoplasm • Act as signals in translation (identifies molecule as being RNA)
What is the function of the 3’ polyadenyl tail
facilitates nuclear export and translation
What is the function of 5’ cap (a nucleotide
derivative)
facilitates transport to the cytoplasm and
attachment to the ribosomes by acting as signals in translation(identifies molecule as
being RNA)
protects the RNA transcript from degradation by the endogenous cellular exonucleases by Increasing stability
