Prokaryotic Gene Expression - Venk Flashcards
What is the preferred source of carbon for bacteria (Glucose or Lactose)?
Glucose (net 32 ATP)
True or False: Under glucose limiting conditions, bacteria can utilize lactose as an energy source.
True
In principle, the three gene products that are required for metabolizing lactose are …?
a) permease (y gene)
b) beta-galactosidase (z gene)
c) transacetylase (a gene)
True or False: In the absence of lactose, repressor protein of Lac operon normally binds to operator and shuts off the expression of Z,Y, A genes.
True
Under glucose limiting condition and lactose excess condition, what protein binds to cAMP to activate gene transcription by RNA polymerase?
Catabolite Activator Protein (CAP) binds to cAMP under low glucose conditions to induce the lac operon and facilitate the RNA polymerase
Define polycistronic messages. (Is the mRNA transcript contiguous?)
Polycistronic messages are multiple genes that are controlled with one operon
True or False: Tryptophan can be synthesized in bacteria.
True
Chorismate to Tryptophan synthesis involves translational control that is coordinated by _______ sequences that are located upstream (5’) from the transcription start site of the mRNA.
Leader (5 sequences)
What are two forms of leader sequences of mRNA that can either promote translation or stall translation?
The stem and loop mRNA structure can shut down translation.
A stem only mRNA structure can promote translation.
What are the few major differences that we discussed in class between prokaryotic and Eukaryotic gene expression?
In prokaryotes, there is no nucleus so translation and transcription can occur at the same time.
In eukaryotes, the transcription and translation occur at different times/locations.
What protein binds to the lactose repressor?
allo-lactose binds to the repressor so it does not bind to the operator (thus allowing gene transcription).
