Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

12. Gene Regulation in Prokaryotes

Lac Operon

Genetics

12. Gene Regulation in Prokaryotes

Lac Operon

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Multiple Choice

Which of the following events will most likely increase the concentration of lac gene products in an E. coli cell?

Addition of glucose to the growth medium

Addition of lactose to the growth medium

Removal of the CAP (catabolite activator protein) binding site from the lac operon

Mutation causing constitutive expression of the lac repressor

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Verified step by step guidance

Step 1: Understand the lac operon system in E. coli, which controls the expression of genes involved in lactose metabolism. The lac operon is regulated by the presence or absence of lactose and glucose in the environment.

Step 2: Recall that the lac operon is normally repressed by the lac repressor protein, which binds to the operator region and prevents transcription when lactose is absent.

Step 3: When lactose is present, it acts as an inducer by binding to the lac repressor, causing it to change shape and release from the operator, allowing transcription of lac genes to proceed and increasing lac gene product concentration.

Step 4: Consider the role of glucose: the presence of glucose inhibits the activation of the lac operon through catabolite repression, mediated by CAP (catabolite activator protein). When glucose is added, CAP does not bind to its site, reducing lac operon expression.

Step 5: Analyze the effects of the other options: removal of the CAP binding site reduces activation, and mutation causing constitutive expression of the lac repressor would keep the operon repressed. Therefore, addition of lactose is the event that most likely increases lac gene product concentration.