Table of contents

1. Overview of Cell Biology2h 49m
2. Chemical Components of Cells1h 14m
3. Energy1h 33m
4. DNA, Chromosomes, and Genomes2h 31m
5. DNA to RNA to Protein2h 31m
6. Proteins1h 36m
7. Gene Expression1h 42m
8. Membrane Structure1h 4m
- The Lipid Bilayer
  38m
- Membrane Proteins
  25m
9. Transport Across Membranes1h 52m
10. Anerobic Respiration1h 5m
11. Aerobic Respiration1h 11m
12. Photosynthesis52m
13. Intracellular Protein Transport2h 18m
14. Cell Signaling1h 28m
15. Cytoskeleton and Cell Movement1h 39m
16. Cell Division3h 5m
17. Meiosis and Sexual Reproduction50m
18. Cell Junctions and Tissues48m
19. Stem Cells13m
- Stem Cells
  13m
20. Cancer44m
21. The Immune System1h 6m
22. Techniques in Cell Biology1h 41m

7. Gene Expression

Transcriptional Regulators

Cell Biology

7. Gene Expression

Transcriptional Regulators

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Multiple Choice

If lactose is present, what happens to the lac operon?

It is activated

It is repressed

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Verified step by step guidance

Understand the components of the lac operon: The lac operon consists of three structural genes (lacZ, lacY, and lacA), a promoter, an operator, and a repressor protein. These components work together to regulate the metabolism of lactose in bacteria.

Identify the role of lactose: Lactose acts as an inducer in the lac operon system. When lactose is present, it binds to the repressor protein, causing a conformational change.

Explain the effect of lactose binding: When lactose binds to the repressor, it prevents the repressor from binding to the operator region of the lac operon. This removal of the repressor allows RNA polymerase to access the promoter.

Describe the activation of the operon: With the repressor no longer blocking the operator, RNA polymerase can transcribe the structural genes of the lac operon, leading to the production of enzymes necessary for lactose metabolism.

Summarize the outcome: The presence of lactose activates the lac operon, allowing the cell to produce the enzymes required to break down lactose into glucose and galactose, which can then be used for energy.