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The problem of the operon in E. coli is discussed, focusing on four mutants (A, B, C, and D) that affect the regulation of an inducible and negatively controlled system.

Problem Introduction

• Four mutants (A, B, C, and D) in E. coli are studied for their impact on the regulation of an inducible and negatively controlled system.

• These mutants were used in experiments to determine the presence or absence of two enzymes in the system.

• The system has two enzymes and is regulated by an inducer.

Experimental Results

• Partial diploids carrying a factor F with bacterial DNA related to the analyzed enzymatic system were obtained.

• The results of these experiments are presented in a table.

Operon Functioning

• A schematic representation of how the operon functions is provided.

• The regulator gene encodes a regulatory protein that binds to the operator region.

• In the presence of an inducer, the regulatory protein no longer binds to the operator, allowing RNA polymerase to transcribe genes encoding enzymes.

Mutant Analysis

Mutant 1 (A)

• Mutant 1 shows functional enzyme 2 but lacks enzyme 1.

• The mutation is likely located in the gene encoding enzyme 1.

Mutant 2 (B)

• Mutant 2 fails to produce both enzymes when induced.

• The mutation is likely located in the gene encoding enzyme 2.

Mutants 3 (C) and 4 (D)

• Both mutants show positive results for enzyme production regardless of induction status.

• Possible explanations include a mutation in either the regulator gene or operator region.

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Further analysis of mutants reveals insights into potential mutations affecting specific genes and their corresponding enzymes.

Mutant 1 (A) Analysis

• The mutation in mutant 1 is likely located in the gene encoding enzyme 1.

• This suggests that the non-functioning gene results in a lack of enzyme production, even when induced.

Mutant 2 (B) Analysis

• The mutation in mutant 2 is likely located in the gene encoding enzyme 2.

• This explains why both enzymes fail to be produced when induced.

Mutants 3 (C) and 4 (D) Analysis

• Mutants 3 and 4 show positive results for enzyme production regardless of induction status.

• Possible explanations include mutations in either the regulator gene or operator region, affecting their functionality.

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Exploring potential causes for positive results in mutants with disrupted regulation.

Regulator Gene or Protein Explanation

• One possible explanation for positive results in mutants with disrupted regulation is a mutation in the regulator gene.

• If there are no functional regulatory proteins, RNA polymerase can freely transcribe genes regardless of induction status, leading to enzyme production.

Operator Region Explanation

• Another possibility is a mutation in the operator region.

• If the operator cannot bind to the regulatory protein due to structural changes caused by the mutation, RNA polymerase can still transcribe genes without proper regulation.

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Understanding how mutations affect specific genes and their corresponding enzymes.

Mutant 3 (C) Analysis

• Positive results for both enzymes suggest that either the regulator gene or operator region may be mutated.

• Further investigation is needed to determine which component is affected.

Mutant 4 (D) Analysis

• Similar to mutant 3, positive results indicate potential mutations in either the regulator gene or operator region.

• Additional analysis is required to identify the specific component affected.

Understanding the Mutation in Montante 5

The speaker discusses the mutation in Montante 5 and its impact on gene regulation. They mention that they are investigating three mutant genes, including Montante 4, to determine if they are regulators or operators.

• The speaker quickly dismisses the possibility of Montante 5 being a promoter because if the promoter is damaged, transcription of the enzymes will not occur.

• Without transcription of these enzymes, it is impossible to obtain positive results.

• The speaker emphasizes that both the polymerase and product need to function perfectly for an inducible negative control system.

• It is known that Montante 5 has a mutation in the operator and that the enzyme is not broken.

• This suggests that there may be a mutation in one of the two genes (Montante 3 or Montante 4) that code for regulatory proteins.

Investigating Mutations in Operator and Regulator

The speaker explores the potential mutations in both the operator and regulator genes.

• When dealing with merodiploids, it is important to consider how mutations affect gene expression.

• If only one of the two operators is mutated, gene expression will always be constitutive.

• By approaching the regulator gene, it becomes clear that it can bind to both operators.

• With an inducer present, one operator will not be expressed as much as without an inducer.

• However, if this regulator protein binds to one operator but not the other, it can still produce with an inducer present.

Identifying Mutated Genes

The speaker explains how they can identify which genes are mutated based on their findings so far.

• Based on previous information, it is known that Gene A in Montante 5 codes for a regulatory protein.

• The speaker suggests that Genes 6 and 7 need to be investigated further to determine which one is mutated.

• Although it is already known that the promoter cannot be mutated, further investigation is necessary to understand why the results do not align.

Contrasting Results with Previous Findings

The speaker highlights the differences between the current findings and previous observations.

• It is clear that the regulator gene in Montante 5 is different from what was observed previously.

• The mutations in this regulator gene result in constitutive expression of one enzyme but not the other.

• This explains why one enzyme functions perfectly even with a mutation, while the other does not respond to an inducer.

Understanding Mutations in Enzyme CCE

The speaker discusses mutations in enzyme CCE and their impact on gene expression.

• It is uncertain whether there are mutations in enzyme CCE, but it is likely based on previous observations.

• These mutations cause constitutive expression of one enzyme regardless of an inducer being present or not.

Timestamps have been associated with bullet points as requested.

Mutations in Genes 3 and 4

The speaker discusses mutations in genes 3 and 4, which are being investigated to determine if they are regulators or operators.

Mutations in the Promoter Region

• If the promoter is broken, RNA polymerase cannot bind, resulting in no transcription of the enzymes.

• Without transcription of these enzymes, it is impossible to obtain a positive result.

• The promoter must be intact for proper functioning of the polymerase and enzyme production.

Mutation in Gene 5

• Gene 5 has a mutation in the operator region.

• This mutation indicates that gene 5 codes for an enzyme that is not broken.

• Even without an inducer present, gene 5 still produces the enzyme.

Testing Different Scenarios

• If only one of the two operators is mutated, gene expression will always be constitutive.

• If one of the regulators is mutated, it can still bind to both operators with or without an inducer present.

• However, if the regulator that produces this protein is mutated, it cannot bind anywhere and no expression occurs.

Investigating Mutations in Regulator Genes

The speaker explores mutations in regulator genes and their impact on gene expression.

Mutations in Regulator Genes

• One of the two regulator genes is mutated (e.g., gene A).

• This mutated regulator protein can still bind to both operators with or without an inducer present.

• With an inducer present, gene expression occurs; without it, there is no expression.

Determining Mutated Genes

The speaker explains how to determine which genes are mutated based on previous findings.

Promoter Analysis

• Although it was previously determined that the promoter cannot be mutated, further analysis is still necessary to understand the results.

Differentiating Mutated Genes

• The regulator gene has been identified, and it can bind to both operators.

• However, only one of the two enzymes produced by these genes is functional.

• This indicates that the mutation is likely in one of the enzyme-coding genes (genes 6 or 7).

Understanding Constitutive Expression

The speaker discusses constitutive expression and its relation to mutations in the operator region.

Constitutive Expression with Operator Mutation

• Mutations in the operator region result in constitutive expression.

• Even without an inducer present, gene expression occurs consistently.

• This explains why one of the mutated enzymes (gene 6) functions properly regardless of inducer presence.

Conclusion

The speaker concludes by summarizing the findings and emphasizing the importance of analyzing results carefully.

Analyzing Results

• Careful analysis of results helps identify which genes are mutated and their impact on gene expression.

• In this case, mutations in specific genes lead to constitutive expression or no expression at all.

• Understanding these patterns allows for a better understanding of genetic regulation.

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This section is in Spanish and the transcript mentions that the first part is not transcribed, but the second part is.

Subtopic Title

• The first part of the transcript is not transcribed.

• The second part of the transcript is available for study.