Question
In the lac operon, the z gene codes for :
This question was previously asked in
NEET UG Re-Exam 2026 Question Paper (21-Jun-2026)
The correct answer is
beta-galactosidase
Lac Operon Gene Function Explained
The lac operon is a genetic unit in bacteria, like E. coli, that enables the metabolism of lactose. It contains several genes, including structural genes that code for specific enzymes.
Lac Operon Structural Genes
The structural genes within the lac operon and their functions are:
- lacZ gene: Codes for the enzyme beta-galactosidase.
- lacY gene: Codes for the enzyme permease.
- lacA gene: Codes for the enzyme transacetylase.
z Gene Product: Beta-galactosidase
The question specifically asks what the z gene codes for. Based on the lac operon structure:
- The lacZ gene is responsible for producing beta-galactosidase.
- Beta-galactosidase is crucial as it breaks down lactose into glucose and galactose, allowing the bacteria to utilize it as an energy source.
Therefore, the z gene codes for beta-galactosidase.
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Similar Questions
- Arrange the following steps of DNA fingerprinting in a correct sequence.
A. Isolation of DNA and its digestion by restriction endonucleases.
B. Hybridisation using a labelled VNTR probe.
C. Transferring of separated DNA fragments to synthetic membranes.
D. Detection of hybridised DNA fragments by autoradiography.
E. Separation of DNA fragments by electrophoresis.
Choose the correct answer from the options given below : - Which of the following statements are correct with reference to packaging of DNA helix ?
A. Histones are organized to form a unit of eight molecules called histone octamer.
B. Histones are negatively charged basic proteins.
C. Histones are rich in the basic amino acid residues - lysine and arginine.
D. The positively charged DNA is wrapped around the histone octamer to form nucleosome.
E. The packaging of chromatin at higher levels requires an additional set of proteins called non-histone chromosomal proteins.
Choose the correct answer from the options given below : - The correct statement with regard to the secondary structure of DNA/RNA is :
- Which of the following statements are correct with reference to a transcription unit ?
A. A transcription unit in DNA is defined primarily by three regions : promoter, structural gene and terminator.
B. The promoter is said to be located towards the 5'-end of the structural gene.
C. The promoter is a DNA sequence that provides binding site for RNA polymerase.
D. The promoter defines the template and coding strands.
E. The terminator is located towards the 3'-end of the coding strand and it defines the end of the process of transcription.
Choose the correct answer from the options given below : - Which of the following statements about lac-operon is correct ?
- Which of the following enzymes synthesizes precursor mRNA ?
Important Questions from Molecular Biology
- Arrange the following steps of DNA fingerprinting in a correct sequence.
A. Isolation of DNA and its digestion by restriction endonucleases.
B. Hybridisation using a labelled VNTR probe.
C. Transferring of separated DNA fragments to synthetic membranes.
D. Detection of hybridised DNA fragments by autoradiography.
E. Separation of DNA fragments by electrophoresis.
Choose the correct answer from the options given below : - Which of the following statements are correct with reference to packaging of DNA helix ?
A. Histones are organized to form a unit of eight molecules called histone octamer.
B. Histones are negatively charged basic proteins.
C. Histones are rich in the basic amino acid residues - lysine and arginine.
D. The positively charged DNA is wrapped around the histone octamer to form nucleosome.
E. The packaging of chromatin at higher levels requires an additional set of proteins called non-histone chromosomal proteins.
Choose the correct answer from the options given below : - The correct statement with regard to the secondary structure of DNA/RNA is :
- Which of the following statements are correct with reference to a transcription unit ?
A. A transcription unit in DNA is defined primarily by three regions : promoter, structural gene and terminator.
B. The promoter is said to be located towards the 5'-end of the structural gene.
C. The promoter is a DNA sequence that provides binding site for RNA polymerase.
D. The promoter defines the template and coding strands.
E. The terminator is located towards the 3'-end of the coding strand and it defines the end of the process of transcription.
Choose the correct answer from the options given below : - Which of the following statements about lac-operon is correct ?
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