Answer:
An amino acid activates the repressor so that the repressor binds to the operator and prevents transcription.
Explanation:
In an operon, promoter is followed by operator which is finally followed by the structural genes to be transcribed. RNA Polymerase binds to the promoter and initiates transcription. A repressor can negatively control the transcription process by binding to the operator so that the RNA Polymerase is not able to move forward and transcription is halted.
For example: in trp operon, tryptophan amino acid binds to the repressor molecule which leads to change in repressor's shape. The repressor is now able to bind to the operator and prevent transcription.
A physical change occur when objects or substances undergo a change that does not change in which the composition of a substance changes or one or more substances combine or break up from new substances.
The nervous system is responsible for voluntary/involuntary movement. The glands of the endocrine system produce hormones that are responsible for growth, metabolism, sexual function, etc.
The other molecules are triglycerides, low density lipoprotein, and high density lipoprotein.
spongy bone is found in the bones of the skull, sternum, vertebrae, the pelvis, the lining of the marrow cavity and the epiphysis.
