a protein or short non-coding RNA, which can combine with a specific site on a length of DNA inhibiting or activating transcription of the gene
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Where do transcription factors bind?
At specific promoter regions on DNA
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What substrate can E.coli respire in the absence of glucose?
Lactose
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Which 2 enzymes are produced in the presence of Lactose?
Lactose Permease and Beta galactosidase
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Which structural gene codes for Lactose permease?
Lac Y
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Which structural gene codes for Beta galactosidase?
Lac Z
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What is the function of Lactose Permease?
It helps E.coli absorb lactose by making its cell surface more permeable to lactose
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What is the function of Beta galactosidase?
causes the breakdown (by hydrolysis) of lactose to glucose and galactose
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What is Lac I and what does it code for?
a regulatory gene coding for a repressor protein
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What does the repressor protein do in the absense of Lactose?
it binds to the operator region ( Lac O)
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What prevents RNA Polymerase from binding to the Promoter region?
the binding of the repressor protein to the operator region ( Lac O)
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What effect does the prevention of RNA polymerase binding to the promoter region have?
The genes Lac Y and Lac Z aren't expressed, so Lactose permease and Beta galactosidase aren't produced
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What is the Final effect of the absence of Lactose?
Enzymes for lactose metabolism are not made, the genes are off
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Why is the Lac operon system beneficial?
ATP and aminoacids aren't wasted producing enzymes to digest lactose that isn't present to be digested
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What effect does the presence of lactose have on the lac operon system?
Lactose binds to the repressor protein altering its shape, preventing it from binding to the operator region ( Lac O) , RNA polymerase can bind to the promoter region and begin transcribing the structural genes Lac Y and Z
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What are 4 ways genes are regulated?
Transcriptional, Post-transcriptional, Translational and Post-translational
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What is transcriptional gene regulation?
turning genes on and off
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What is post-transcriptional gene regulation?
mRNA modified , regulating translation and the types of proteins produced
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What is translational gene regulation?
When translation is stopped or started
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What is post-translational gene regulation?
When proteins are modified after synthesis which changes their functions. Involves the activation of proteins
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What is the first stage in Post-Transcriptional gene regulation?
DNA with its Exons and Introns is transcribed into mRNA by RNA polymerase , resulting in primary mRNA
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What is the second stage in Post-Transcriptional gene regulation?
Primary RNA is edited, RNA introns are removed
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What is the 3rd stage in Post-Transcriptional gene regulation?
The remaining RNA exons corresponding to DNA exons are joined
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What enzyme catalyses the Splicing and editing of primary mRNA?
Endonuclease enzyme
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What is added to mRNA in the final stage of Post-Transcriptional Gene regulation?
A cap (modified nucleotide) is added to the 5' end and a Tail (long chain of adenine nucleotides) is added to the 3' end
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Why are caps and tails added?
Both help stabilise mRNA and delay degradation in the cytoplasm. Cap promotes binding to ribosomes.
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How does RNA Editing occur?
By substitution , deletion and insertion
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What effect does RNA editing have?
Same effect as Point mutations, resulting in the synthesis of a different protein with different functions
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What are Protein Kinases?
enzymes catalysing the addition of phosphate groups to proteins
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What effect does Phosphorylation have on a protein?
Activates enzymes. It changes its tertiary structure changing its functions
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What is cyclic AMP (cAMP)?
A Second messenger that activates proteins
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How does cAMP activate enzymes and stimulate transcription?
Signalling molecules binds to receptor on plasma membrane which activates the trans-membrane protein activating G protein
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What effects does the Activation of the G Protein have?
It activates Adenyl cyclase enzymes which catalyses the formation of many cAMP from ATP
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What does cAMP activate?
Protein Kinase A (PKA)
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What does activated PKA do?
It catalyses the phosphorylation of proteins (Also hydrolysing ATP in the process)
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What effect does phosphorylation have?
It activates enzymes
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What protein does PKA also phosphorylate which enters the nucleus?
CREB protein, which enters the nucleus and acts as a transcription factor
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Other cards in this set
Card 2
Front
Where do transcription factors bind?
Back
At specific promoter regions on DNA
Card 3
Front
What substrate can E.coli respire in the absence of glucose?
Back
Card 4
Front
Which 2 enzymes are produced in the presence of Lactose?
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