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The Lac Operon

How do the microorganisms that cause food spoilage get to your food? Bread will grow mold if not kept cool, meat will go bad, fruits and vegetables will rot. The changes to food are the result of the action of various organisms, primarily bacteria and fungi. Fungi reproduce using spores which are very small and can travel through the air. Bacteria are very small and can also form spores. Although largely invisible, spores and bacteria are common and found everywhere. They are easily transported on clothing, skin, in food products brought in from outside, and can be air born as well. Cleanliness can reduce the exposure of our food to bacteria and fungi but it is impractical to try and completely remove these organisms from our environment.

View the animation below, then complete the quiz to test your knowledge of the concept.






1The lac repressor binds to what site within the lac operon?
A)lacZ
B)lacO
C)lacA
D)lacl
E)lacP



2Which of the following is not part of the lac operon?
A)lacO
B)lacZ
C)lacA
D)lacl
E)lacP



3The lac repressor is inactivated by binding to which of the following?
A)lactose
B)betagalactosidase
C)transcription factors
D)glucose
E)allolactose



4The polycistronic mRNA is transcribed from the lac operon when lactose is present in the cell.
A)True
B)False



5The lac repressor protein is active in the absence of lactose within the cell.
A)True
B)False







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