13. Choose/mark the correct word to complete the statement. Consider the regulation of CAMP and the Lac operon. If bacteria are in a medium containing low glucose, but suddenly glucose concentration in the medium increases by ten fold, then we expect that CAMP will/ will not increase inside the cell.

In your own words describe in detail what happens at the lac operon in each of the following situations Lactose, no glucose (high cAMP) No lactose or glucose (high cAMP) Lactose and glucose (low cAMP) Glucose, no lactose (low cAMP)

The lac operon contains three genes: lacZ, lacY, and lacA for ß-galactosidase, galactoside permease, and thiogalactoside transacetylase, respectively. The operon also contains a promoter site and an operator site. The regulatory gene includes the I gene for the Lac repressor protein and a promoter for that gene. regulatory gene DNA P₁ lacl gene The lac operon undergoes negative regulation. In the normal condition, the Lac repressor protein is active. Allolactose, an isomer of lactose, is the signal molecule that binds to the Lac repressor. P O Increase in gene products The I gene is disabled. Lactose is present in the cell. The Lac repressor dissociates from DNA. lac operon lacZ gene Determine which events will increase the concentration of lac gene products and which will decrease the concentration of lac gene products. Allolactose is not present in the cell. lacy gene lacA gene Decrease in gene products Allolactose binds to the Lac repressor protein. The Lac repressor remains bound…

E. coli is given lactose as a nutrient source. This results in the activation of the lac operon only in the presence of glucose deactivation of the lac operon only in the absence of glucose deactivation of the lac operon only in the presence of glucose activation of the lac operon only in the absence of glucose Question 25 Transduction occurs when a cell takes up DNA from the environment cells are stressed a virus transfers DNA to a cell an F+ cell transfers one strand of DNA to an F- cell MacBe

28.  Which statement does NOT explain why the lac operon would not be effectively regulated by an attenuation mechanism like the trp operon? 1.Lactose is a substrate for the lac operon protein products.   2.Products of lac operon enzymes are not used in protein synthesis.   3.Transcription and translation do not happen simultaneously for the lac operon.   4.Attenuation is a suitable regulatory mechanism for anabolic amino acid pathways.   5.All of these statements explain why regulation by attenuation would not be effective for the lac operon.

Like the lac operon, the hexose operon is controlled by a separate regulatory protein under the control of its own promoter (see the schematic of the operon below). The hexose regulatory protein is sensitive to fatty acyl CoA levels. When all hexose fuel sources are depleted, the bacteria switch to lipid metabolism and fatty acyl CoA levels increase. This turns expression of the hexose operon off. +1 +1 Regulatory Gene Pregulator P operon Hexose Operon Genes regulator promoter operon promoter

Match each description with the appropriate label (allo)Lactose binds to the lac repressor, causing it to release from the promoter CAP binds CAMP to stimulate transcripti of the lac operon ✓ [Choose ] positive control of an inducible gene negative control of an inducible gene [Choose]