Biol 3025 Study Guide Test.

BIOL 3025 STUDY GUIDE TEST. The lac operon is expressed when A) glucose is high and lactose is absent. B) glucose is low and lactose is absent. C) glucose is low, regardless of the presence or absence of lactose. D) glucose is high and lactose is present. E) glucose is low and lactose is present. - CORRECT ANSWER E When in a complex with ________, the CAP protein binds to the CAP site and ________ the expression of the lac operon. A) glucose ; switches on B) lactose ; switches on C) cAMP ; switches on D) cAMP ; switches off E) glucose ; switches off - CORRECT ANSWER C In the absence of lactose, the lac repressor is A) active and can bind to the operator. B) inactive and can bind to the operator. C) active and cannot bind to the operator. D) inactive and cannot bind to the operator. E) inactive and cannot bind to the promoter. - CORRECT ANSWER A Which region associated with the lac operon is not involved in the binding of RNA polymerase? A) lacO B) lacZ Correct C) CAP binding site - CORRECT ANSWER B How does glucose effect the lac operon? A) When glucose levels are high, glucose binds to and deactivates the repressor, preventing it from binding to the DNA. B) When glucose levels are low, it stimulates the production of cAMP, which binds to and deactivates the repressor, preventing it from binding to the DNA. C) When glucose levels are low, glucose binds to and activates the repressor, causing it to associate with the DNA. D) When glucose levels are high, it stimulates the production of cAMP, which binds to and deactivates the CAP protein, preventing it from binding to the DNA. E) When glucose levels are low, it stimulates the production of cAMP, which binds to and activates the CAP protein, allowing it to bind to the DNA. - CORRECT ANSWER NOT A B C E NOT A B D Why does the concentration of glucose have an effect on the transcription of the lac operon? A) Glucose is an important cell signaling molecule. B) All of these are true C) The lac operon functions to metabolize glucose, lactose, and other small sugars. D) Glucose is the preferred sugar for the bacteria. If it is present, lactose metabolism is suppressed. E) Glucose is a precursor of lactose. - CORRECT ANSWER D DNA is associated with proteins to form _____. - CORRECT ANSWER chromatin A _____ is composed of DNA wrapped around an octamer of histone proteins. - CORRECT ANSWER nucleosome An activator can increase transcription by attracting a _____ to the region. - CORRECT ANSWER histone acetyltransferase Addition of (-COCH₃) groups to histone amino terminal tails results in a/an _____ in gene expression. - CORRECT ANSWER increase