What are the steps involved in B cell activation?
What will be an ideal response?
B cell activation involves many steps. First, antigen-presenting cells present antigenic determinants to Th cells that have complementary binding sites to the presented antigen. Next, Th cells differentiate into Th2 cells. Then, clonal selection takes place, where only the B cells with BCRs complementary to the antigenic determinants will be recognized. When a BCR on the surface of an unactivated B cell binds its epitope, the BCR-antigen complex is endocytosed, and the B cell then displays the epitope on MHC, behaving as an antigen presenting cell. A complementary Th2 cell binds to the B cell by recognizing its antigenic determinant-MHC II complex and then secretes IL-4, which activates the B cell to proliferate rapidly and produce memory cells and plasma cells.
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A (n) ________ is a special type of lysosome used by a cell to selectively digest and recycle cytoplasmic contents, such as mitochondria.
A. recycling vacuole B. autophagosome C. turnover lysosome D. suicide vacuole
The sarcoplasmic reticulum of a muscle fiber is the ___________
Fill in the blank(s) with the appropriate word(s).
The half-life of carbon-14 is approximately 5,700 years. Using this information scientists have been able to determine the age of some artifacts left by humans. A scientist wants to know approximately how old a piece of wood was that she found on the floor in an old cave that had recently been discovered. She removed the wood (with permission) to her laboratory. Her wood sample contained 2 grams of carbon-14. If the age of the wood was determined to be 22,800 years old, how much carbon-14 originally existed in this piece of wood?
A. 16 grams B. 32 grams C. 4 grams D. 8 grams E. 12 grams
Which of the following microorganisms associated with food poisoning thrives in cold storage?
A. Salmonella spp. B. Shigella spp. C. Clostridium botulinum D. Escherichia coli E. Listeria monocytogenes