Exam 4 Quiz 4 Flashcards
do all proteins need to be constitutive?
No! They only make the proteins that they need at that time
post-translational control
the protein is already made, how the function is limited after its made
regulating enzyme activity post-translationally
feedback inhibition
feedback inhibition
where you have a series of enzymes that go onto make an end product.
-the end product of a pathway typically interrupts the function of the first enzyme in the pathway
first enzyme in the pathway
allosteric enzyme
allosteric enzyme
-have a second, important site (allosteric site) along with the active site (the main site)
allosteric site
where the end product binds when it is in excess which then goes onto disrupt the active site inhibiting the process from continuing (saves energy)
is Feeback reversible
yes
concerted feedback inhibition
-involves the use of isoenzymes which are different proteins that catalyze the same reaction but are under different regulatory controls
example of concerted feedback inhibition
aromatic AA synthesis, each have a different regulatory control but working towards the same product
if more than one end product
all end products must be in excess in order for synthesis to be completely inhibited
covalent modification of enzymes
occurs throughout the addition and removal of a particular group/model
main groups used to modify enzymes
-Adenosine monophosphate
-Adenosine diphospahte
-inorganic phosphate
-methyl groups
Glutamine synthetase
making glutamine, when glutamine levels are staying high AMP is added on which causes the glutamine to reduce
regulation of translation at translation level
regulating enzyme synthesis vis:
-riboswitches
-regulatory RNA/small RNA
riboswitches
-mRNA contains binding site for specific metabolite
-when metabolite bound it alters folding of mRNA hiding the Shane-Dalgarno sequence
aptamer region
specific secondary structure that allows for metabolite bonding
when specific metabolite is bound
-translation is blocked
-inhibits the Shine dalgarno sequence from being recognized
when no metabolite is bound
shine dalgarno sequence is seen by 30S or 16S rRNA to continue with the process
Regulatory RNA/small RNA
binding to an mRNA molecule due to complimentary base pairing
small RNA
-40-400 nucleotide bases
-act as regulatory
-exert control through base pairing
regulation through 4 different mechanisms
-hides shine dalgarno
-opens shine dalgarno
-increases stability
-decreases stability
Regulation of transcription
-at transcription level (only prokaryotes)
-regulating enzyme synthesis
-attenuation
regulating enzyme synthesis only occurs in prokaryotes because
transcription and translation need to be occurring at the same time, only seen in prokaryotes bc no nucleus
Attenuation
at leader sequence there are tandem tryptophan residues (or whatever AA you need) right next to one another in the N terminal
what does the rest of the leading sequence form?
secondary structures
leader sequence can fall inot different scenarios based on
what is happening in the cell
if tryptophan is plentiful
ribosome will translate leader sequence and inhibit further transcription
if tryptophan is in short supply
ribosome will be stalled during translation but transcription will continue
when there is excess tryptophan (explain)
-want to turn off transcription
-base pairing is done close to the leader sequence
-RNA polymerase terminates because of the stem loop structure
when there is not enough tryptophan
-ribosome gets stopped because there is not enough tryptophan
-secondary structure forms earlier because ribosome takes longer to move
-RNA polymerase can continue because the stem loop structure is further away from the leader sequence
