Answer: we can make observations directly by seeing, feeling, hearing, and smelling, but we can also extend and refine our basic senses with tools: thermometers, microscopes, telescopes, radar, radiation sensors, X-ray crystallography, mass spectroscopy, etc. And these tools do a better job of observing than we can!
The extracellular glucose inhibit transcription of the lac operon (D) by reducing the levels of intracellular cAMP.
Lac operon is the assembly of various genes that are involved in the uptake and metabolism of lactose of E. coli or any other bacteria. It consists of a regulator gene, promoter gene, operator and structural gene. Structural genes are three: z, y and a. Each codes for a different enzyme.
cAMP is the cyclic Adenosine Monophosphate. It is produced by the bacteria when there are low levels of glucose in it. Hence it is also named as hunger signals. Therefore, cAMP is responsible for activating the operon to produce lactose.
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We need the context of the work of you want us to answer
You are looking at tissue under a microscope. One cell shows half the amount of DNA of some of the other cells. This cell is most likely to be in the G1 phase where the cell has just divided.
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