In negative regulation, a repressor molecule binds to the operator of an operon and terminates transcription. The lac operon is a negatively controlled inducible operon, where the inducer molecule is allolactose.
Gene regulation governing lactose operon of E. coli that involves the lac I gene product is:
Held on 30 Apr 2015 · Verified 9 Jul 2026.
Positive and inducible because it can be induced by lactose
Negative and inducible because repressor protein prevents transcription
Negative and repressible because repressor protein prevents transcription
Feedback inhibition because excess of β - galactosidase can switch off transcription
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Which of the following are the post-transcriptional events in an eukaryotic cell? A. Transport of pre-mRNA to cytoplasm prior to splicing. B. Removal of introns and joining of exons. C. Addition of methyl group at 5' end of hnRNA. D. Addition of adenine residues at 3 ' end of hnRNA. E. Base pairing of two complementary RNAs. Choose the correct answer from the options given below :
Match List I with List II: $\begin{array}{|l|l|l|l|}\hline & \text{List - I} & & \text{List - II} \\\hline \text{A}. & \text{Alfred Hershey and Martha Chase} & \text{(i)} & \text{Streptococcus pneumoniae} \\\hline \text{B.} & \text{Euchromatin} & \text{(ii)} & \text{Densely packed and dark-stained} \\\hline \text{C.} & \text{Frederick Griffith} & \text{(iii)} & \text{Loosely packed and light-stained} \\\hline \text{D.} & \text{Heterochromatin} & \text{(iv)} & \text{DNA as genetic material confirmation} \\\hline\end{array}$ Choose the correct answer from the options given below:
Who proposed that the genetic code for amino acids should be made up of three nucleotides?
Which factor is important for termination of transcription?
Histones are enriched with -
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