Table of contents

1. Introduction to Microbiology3h 22m
2. Disproving Spontaneous Generation1h 18m
3. Chemical Principles of Microbiology3h 38m
4. Water1h 28m
5. Molecules of Microbiology2h 23m
6. Cell Membrane & Transport3h 28m
7. Prokaryotic Cell Structures & Functions5h 52m
8. Eukaryotic Cell Structures & Functions2h 18m
9. Microscopes2h 46m
10. Dynamics of Microbial Growth4h 36m
11. Controlling Microbial Growth4h 10m
12. Microbial Metabolism5h 16m
13. Photosynthesis2h 31m
14. DNA Replication2h 25m
15. Central Dogma & Gene Regulation7h 14m
16. Microbial Genetics4h 44m
17. Biotechnology3h 0m
18. Viruses, Viroids, & Prions4h 56m
19. Innate Immunity7h 15m
20. Adaptive Immunity7h 14m
21. Principles of Disease6h 57m

15. Central Dogma & Gene Regulation

Glucose's Impact on Lac Operon

Microbiology

15. Central Dogma & Gene Regulation

Glucose's Impact on Lac Operon

Previous problemNext problem

Struggling with Microbiology?

Join thousands of students who trust us to help them ace their exams!Watch the first video

Multiple Choice

When glucose is present:

cAMP is high, CRP binds to the activator binding site, and transcription of the lac operon is turned off.

cAMP is low, CRP binds to the site activator binding site, and transcription of the lac operon is turned on.

cAMP is high, CRP does not bind to the activator binding site, and transcription of the lac operon is turned on.

cAMP is low, CRP does not bind to the activator binding site, and transcription of the lac operon is turned off.

Previous problemNext problem

Verified step by step guidance

Understand the role of cAMP and CRP in the regulation of the lac operon. cAMP (cyclic AMP) is a signaling molecule that, when bound to CRP (cAMP receptor protein), facilitates the binding of CRP to the activator binding site, enhancing transcription of the lac operon.

Recognize that the presence of glucose affects the levels of cAMP. When glucose is abundant, the levels of cAMP are low because glucose inhibits the enzyme adenylate cyclase, which is responsible for converting ATP to cAMP.

Analyze the relationship between cAMP levels and CRP binding. Low cAMP levels mean that CRP cannot bind to the activator binding site, as CRP requires cAMP to change its conformation to a form that can bind to DNA.

Consider the effect on the lac operon transcription. Without CRP binding to the activator site, the lac operon is not activated, and transcription is turned off. This is because the RNA polymerase has a lower affinity for the promoter without the help of CRP.

Conclude that when glucose is present, cAMP is low, CRP does not bind to the activator binding site, and transcription of the lac operon is turned off, which matches the correct answer provided.