Answer:
The correct answer is option B which is when Earth is on perihelion, it is the beginning of summer.
Explanation:
Perihelion and aphelion are Greek words. In Greek hellion means the sun and peri means close while ephe means far.
So the perihelion which is normally two weeks after December it shows the starting of summers.
Some areas of earth begin to come in front of sun due to which the temperature of these areas start rising.
The trp operon is a group of genes that code for enzymes involved in the synthesis of tryptophan, an amino acid.
The regulation of these genes is done by two regulatory processes:
- Transcriptional attenuation
- Post-transcriptional attenuation.
Transcriptional attenuation is the process by which transcription of a gene is reduced by the binding of regulatory proteins to the DNA at or near the promoter region. Post-transcriptional attenuation is a process where degradation of RNA molecules occurs after they are transcribed from DNA, but before they are translated into protein.
<h3 /><h3>How do they modulate trp operon transcript levels?</h3>
- The trp operon is a system of genes that encode the enzymes needed to synthesize tryptophan from indole-3-glycerol phosphate.
- The transcription of these genes is controlled by a repressor protein. When tryptophan levels are high, the repressor binds to the operator and prevents transcription. When tryptophan levels are low, the repressor is not bound to the operator and transcription can proceed.
To learn more about the regulation of trp operon, visit:
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Mitosis
Definition of Mitosis: <span>The process where a </span>single cell<span> divides resulting in generally two identical </span>cells<span>, each containing the same number of </span>chromosomes<span> and genetic content as that of the original </span>cell<span>.</span>