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.
Explanation:
In simple diffusion, small molecules without charges such as oxygen and carbon dioxide flow through a plasma membrane without assistance and without expending energy. Other substances such as proteins, glucose and charged particles called ions cannot pass through the selectively permeable membrane
The similarity between the sea star larva of modern times and some primitive vertebrae larvae suggests that they <span>share a common ancestor with sea stars.</span>
Answer-
Commensalism is a type of relationship where one of the organisms benefits greatly from the symbiosis. The other is not helped but is not harmed or damaged from the relationship. In other words, this is a one-sided symbiotic relationship.
In parasitism, one organism benefits from the relationship but at the expense of the other. The organism may live inside the other's body or on its surface. In some of these parasitic relationships the host dies and in others, it is important that the host remain alive.
Mutualism is a close relationship where both parties benefit. Both species will benefit from the relationship and many of these relationships are ling-lasting.
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