Answer:
Please find the detailed explanation of this statement below
Explanation:
Firstly, a repressed gene is a gene whose expression has been inhibited or repressed. The lac operon in E.coli bacteria is a regulatory unit containing structural genes, a single promoter and operator regions. The promoter is the region where the transcription enzyme (RNA polymerase) binds to in order to transcribe the genes in the lac operon. The structural genes in the lac operon can only be expressed in the presence of lactose sugar.
However, in the absence of lactose, LAC REPRESSOR, which is a transcription factor (protein), prevents the binding of RNA polymerase to the PROMOTER region by binding to the OPERATOR region of the lac operon. This inhibits the expression of the lactose genes in the operon.
Note that, the structural genes in the lac operon (lacZ, lacY, lacA) code for proteins that help break down lactose sugar for energy in the E.coli bacteria. Therefore, a bacteria cell with a repressed lac operon will be unable to degrade lactose sugar.
B. Ocetoclast is the answer.
Answer: pathogen–host coevolution
Explanation:
A major driver of evolution is Reciprocal coevolution between host and pathogen. Rather than pathogen, one-sided adaptation to a nonchanging host, high virulence specifically favoured during pathogen–host coevolution. In all of the independent replicate populations under coevolution, the pathogen ( B. thuringiensis ) genotype BT-679 with known nematocidal toxin genes of C. elegans and high virulence specifically swept to fixation but only some of them go under one-sided adaptation,
so relative change in B. thuringiensis virulence was greater than the relative change in C. elegans resistance is due to the elevated copy numbers of the plasmid containing the nematocidal toxin genes
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