Prokaryotic Gene Regulation Flashcards
The ___ is the prokaryotic mechanism for controlling gene expression
Operon
Operons may be___. The default situation is off, and the sequence of events turns it on
Inducible
Inducible operons produce ____ enzymes
Catabolic
Operons may be ___. The default situation is on, and the correct sequence of events turns it off.
Repressible
Reprensible operons produce ____ enzymes
Anabolic
Lactose is composed of ___+____
Glucose+galactose
The major goal of the ___ is to produce glucose
Lac operon
The mechanism by which glucose influences the function of the Lac operon
Catabolite Repression
High levels of glucose inactive the enzyme ___
Adenylate cyclase
Without adenylate cyclase, cells do not produce ___
cAMP
Second messenger, derived from ATP, essential for many cellular processes
Cyclic Adenosine Monophosphate (cAMP)
cAMP is a ___ in the Lac operon
Positive Regulator
cAMP attaches to a protein called the ___
Catabolite Activator Protein
The cAMP-CAP complex attaches to the promoter region of the ___. When attached to the promoter, cAMP-CAP enhances transcription of the three structural genes (z,y,a).
Lac operon
Cells with a large glucose supply ___ break down lactose
Do not
In cells with both glucose and lactose, ___ determines gene expression
Glucose
Regulatory gene makes an ___ repressor molecule
Immature/inactive
___ serves as a co-repressor. It attaches to app-repressor and induces conformational change
Tryptophan
___ attaches to the operator, blocking structural gene transcription
Repressor-tryptophan complex
When ___ is present, the operon is off
Tryptophan
In ___ there is a high degree of sensitivity to the presence/absence of the molecule made by the anabolic enzymes
Reprensible Operons
The sensitivity is based on usage of the gene segment called the ___.
Leader sequence
The ___ is found within that leader sequence
Attenuator Region
Leader region is completely translated, allowing loop 1-2 and 3-4 to form. The formation of this stem and loop results in the termination of transcription
High Tryptophan Level
Ribosome is stalled at trp codons. Ribosome is waiting for tRNA to translate, which causes RNA polymerase t o pause, loop 2-3 forms, preventing 1-2 and 3-4 formation, allowing transcription to continue
Low tryptophan level
