Question
Under which of the fol le following conditions will the repressor pro 8. Which of the...

Answers
8) repressor protein inhibits the expression of the lac operon by binding to the operator and the allolactose is an inducer of the lac operon it activates the expression of the lac operon by inhibiting lac repressor, so lac repressor, operator and allolactose regulate the expression of genes so the answer is d) all of the above are correct.
9) mutagens are agents which cause mutation, exposure to mutagen increases the rate of mutation, frameshift mutations changes reading frame, base substitutions change a single codon, DNA mutations change the genotype, some mutations can be lethal, all mutations do not change the phenotype because silent mutations change the codon but do not change the amino acid, so the protein is not changed so the answer is d) DNA mutations always results in a change in phenotype.
10) glucose can inhibit the wide range of operons including lac operon, this is achieved by catabolite repression, the CAP protein which activates the expression of these operons require cAMP, glucose inhibits the production of cAMP so in the presence of glucose CAP cannot activate the expression of the genes. so the answer is b) catabolite repression.
(quorum sensing is the signaling between bacterias in a population, constitutive expression the genes are expressed always, chemotaxis is the movement depending on the concentration of chemicals, glycolysis is the breakdown of glucose to pyruvate)