The Question is from neet-botany molecular-basis-of-inheritance , and it was created by the author Mr. NARESH KUMAR K

Question

The lac operon is an example of which type of gene regulation?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Gene regulation in prokaryotes
 **Related Topics**: Operons, lac operon, inducible and repressible systems, positive and negative control
 **Prerequisites**: Understanding of transcription, promoters, operators, repressors, inducers, and the basic structure and function of the lac operon.
## SOLUTION PATHWAY
**Given Information**:
The question asks about the type of gene regulation exhibited by the lac operon.
**Method & Steps**:
1. Understand the lac operon's mechanism.
  Reasoning: The lac operon controls the expression of genes involved in lactose metabolism in *E. coli*.  It's regulated by the presence or absence of lactose.
  Formula/Rule:  None directly applicable, but understanding the components (promoter, operator, repressor, genes for lactose metabolism) is crucial.
2. Determine the type of regulation based on the lac operon's behavior.
  Working: In the absence of lactose, the lac repressor protein binds to the operator, preventing transcription.  When lactose is present, it acts as an inducer, binding to the repressor and causing a conformational change that prevents it from binding to the operator. This allows transcription to occur.  This is a negative control mechanism because the repressor protein actively blocks transcription unless inactivated by an inducer.
  Key Point:  The system is inducible because transcription is turned *on* by the presence of the inducer (lactose).
3. Identify the matching option.
  Result: Negative inducible
  Verification: The description matches the behavior of the lac operon precisely.
## OPTION ANALYSIS
A :x: Positive repressible: This would mean that an activator protein is required for transcription, and its presence is inhibited by a repressor. This is not how the lac operon works.
B :x: Negative repressible: This would mean that transcription is normally on, and a repressor protein turns it off.  This is opposite to the lac operon's behavior.
 C ✓: Negative inducible: This accurately describes the lac operon. Transcription is normally off (due to the repressor), and an inducer (lactose) turns it on.
D :x: Positive inducible: This would mean that an activator protein is required for transcription, and the activator is activated by an inducer.  This is not how the lac operon works.
## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing inducible and repressible systems: Remember that inducible systems are normally off, while repressible systems are normally on.
  2.Confusing positive and negative control:  Positive control involves an activator protein, while negative control involves a repressor protein.
 **Quick Tips**:
  1.Think about the default state of the operon (on or off) and how the presence or absence of a molecule affects that state.
  2.Use mnemonics or diagrams to help remember the different types of gene regulation.

Mr. NARESH KUMAR K · Answer

Positive repressible

Mr. NARESH KUMAR K · Answer

Negative repressible

Mr. NARESH KUMAR K · Answer

The correct Option is "Negative inducible"

Mr. NARESH KUMAR K · Answer

Positive inducible

NEET Botany Molecular Basis of Inheritance MCQs

Select Topic

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

NEET Subjects

Our Bots

Company