<span>A property of t cells, but not b cells, is their </span>ability to form cells that directly kill virus-infected host cells.
I believe it’s the first option
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.
Answer:
Migrate through blood vessels
Explanation:
White blood cells have the ability to perform diapedesis. Diapedesis refers to the emigration of white blood cells through the blood vessels. During the process, white blood cells move along the endothelium of blood vessels and stick to it. The white blood cells squeeze between the endothelial cells to migrate out of the blood vessels.
In this way, white blood cells can reach the site of infection or move from blood to the interstitial fluid to perform immune functions. The ability to migrate in and out of the blood vessels allows the phagocytic neutrophils and macrophages to arrive at the site of pathogen entry, basophils arrive at the site of inflammation to perform their respective functions.
