Answer:
The options A, B, and D are all valid.
Explanation:
- The reason is that some proteins require molecular chaperones if they are to fold properly within the environment of the cell. In the absence of chaperones, a partially folded polypeptide chain has exposed amino acids that can form non-covalent bonds with other regions of the protein itself and with other proteins, thus causing nonspecific aggregation of proteins.
- The option A) is correct because the protein you are expressing in bacteria is being made in large quantities, it is possible that there are not enough chaperone molecules in the bacterium to fold the protein. Expressing the protein at lower levels might increase the amount of properly folded protein.
- The option B) is correct as urea should solubilize the protein and completely unfold it. Removing the urea slowly and gradually often allows the protein to refold. Presumably, under less crowded conditions, the protein should be able to refold into its proper conformation.
- The option C) is not correct as treating the aggregate with a protease, which cleaves peptide bonds, will probably solubilize the protein by trimming it into pieces that do not interact as strongly with one another; however, chopping up the protein will also destroy its enzymatic activity.
- The option D) is correct because overexpressing chaperone proteins might increase the amount of properly folded protein.
- The option E) is not correct as heating can lead to the partial denaturation and aggregation of proteins to form a solid gelatinous mass, as when cooking an egg white, and rarely helps solubilize proteins.
Answer:
antigens
Explanation:
Specific immune responses are triggered by antigens. Antigens are usually found on the surface of pathogens and are unique to that particular pathogen. The immune system responds to antigens by producing cells that directly attack the pathogen, or by producing special proteins called antibodies.
A living thing is something that needs food, water, air, and shelter. Some examples are plants, since they need water; food, which they get from the sun; fresh air; and shelter Just like humans clearly need water, food air, and shelter.
Number 3 is correct
Concept; an abstract idea or general notion
