Repressible system - tryptophan (the effector molecule) interacts with the repressor protein such that it can bind to the operator.
<span>Answer = C,
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A gene pool changes throughout evolution this could be natural selection, genetic drift or a mutation. A gene pool does this to adapt with the needs of the environment it is in
Answer:
The first living organism on Earth are Bacteria in the first era.
Explanation:
Bacteria are the first organism to leave be on Earth. They came into existence about 3.5 billion years in the first era in the waters of small oceans. Then there were anaerobic hetetrophic bacteria because the atmosphere was free of oxygen before. Cyanobacteria then became the first autotrophic organisms and first photosynthesizer that release oxygen to the atmosphere after photosynthesis.
The answer would be C, even though all of them are important for environmental health. Control of sexually transmitted diseases isn't ever talked about enough, especially with teenagers, and because of that, STD rates are on the rise and it's really sad.
Answer: A
Explanation:The Trp operon is responsible for synthesis of the amino acid trytophan when it is not available in the cellular environment.
When the tryptophan is plentiful, a repressor protein binds to two molecules of tryptophan.
Thiss repressor-tryptophan complex binds to the trp operator. This binding prevents the binding of RNA polymerase, so the operon is not transcribed, and no new trptophan is produce.
On the other hand, when tryptophan levels are reduced, the inactive repressor will not bind the tryptophan operator so the operon is transcribed.
Regulation of the trp operon is determined by the concentration of tryptophan; when adequate tryptophan is present in the growth medium, there is no need for tryptophan biosynthesis.
Transcription is turned off when a high concentration of tryptophan is present, and is turned on when tryptophan is absent. The regulatory signal is the concentration of tryptophan itself.
Therefore in the absence of tryptophan, the inactive repressor cannot bind trpO, so operon gene transcription occurs.
