4.6 Regulation of Gene Expression in Bacteria Flashcards
What does a basal level of gene activity mean?
most bacterial gene product are constantly produces in a few copies per cell but when called upon their activity increases
What usually regulated the cellular decision to moderate gene expression?
extracellular environment
When will the genes responsible for metabolic activity and growth be activated?
when conditions are ideal for cell growth and replication
What experiment showed that genes responsible for metabolic activity and growth would be activated when conditions were ideal for cell growth and replicated?
early 1900s when yeast was found to turn on enzymes needed for lactose metabolism in the presence of a lactose containing medium
What is an enzyme?
substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction
What are the three categories genes or enzymes that encode for are classified?
inducible enzymes
repressible enzymes
constitutive enzmes
What are inducible enzymes?
enzymes that are turned on when certain substrates or conditions are present
What is an example of an inducible enzyme?
lactose metabolizing genes
What type of control are inducible enzymes under?
positive
What does it mean for an enzyme to be under positive control?
turned off until a regulator enzymes activates them for use
What are repressible enzymes?
enzymes that are turned off in response to a specific condition
What is an example of a repressible enzymes?
genes required for tryptophan synthesis
What type of control are repressible enzymes under?
negative control
What does it mean for an enzyme to be under negative control?
genetic expression continues until it is told to be shut off by a regulator molecule
What are constitutive enzymes?
produced all the time regardless of environmental or cellular conditions
