What is the correct sequence of events for activation of a B cell by a T-dependent antigen? (1) The B cell binds to a cytokine a
nd then interacts with the TH cell. (2) This causes the B cell to bind the antigen, and then the B cell is activated. (1) Immunoglobulin receptors on the B cell recognize and bind the antigen. (2) An antigen fragment in complex with MHC class 2 is displayed on the B cell's surface. (3) The MHC-antigen complex binds a receptor on a TH cell. (4) The TH cell secretes cytokines that activate the B cell. (1) Identical repeating subunits on the antigen bind to many of the antibodies on the surface of the B cell. (2) This activates the B cell. (1) The T cells bind to an antibody on the B cell. (2) The T cell secretes cytokines. (3) The B cell binds the antigen. (4) The B cell is activated by binding to the antigen.
Antigens that activate B-cells with the help of T-cells are called as T-cells dependent antigens. They are called as such because they are not able to induce a humoral response in organisms that lack T-cells. B-cells response to these antigens take many days, thought antibodies generated are more versatile and have a higher affinity than those generated from T-cell independent activation.
So, the steps for activation of a B cell by a T-dependent antigen are:
(1) Immunoglobulin receptors on the B cell recognize and bind the antigen.
(2) An antigen fragment in complex with MHC class 2 is displayed on the B cell's surface.
(3) The MHC-antigen complex binds a receptor on a TH cell.
(4) The TH cell secretes cytokines that activate the B cell.
<h3><u>Processes that form different fossil types:</u></h3>
The remained parts and elements of an organism that live several years ago is called as fossils.
Due to natural processes like weathering, soil erosion and other geological activities fossils are hard to preserve.
Carbonization, permineralization, recrystallization and replacement are the fossil formation processes.
Carbonization is the chemical reaction forming the thin film of carbon of the organic material.
Permineralization includes the fossils of bones and teeth. The recrystallization process is responsible for changing the micro-structure of the organic materials to form the fossils.
A Cytotoxic T cell is a cell whose activation is mainly aimed at destroying cells that are infected by virus. It is a type of white blood cells that destroys cancerous cells or cells that are impaired especially by viruses. A Cytotoxic cell is also known as T-killer cells, Cytolytic T cells, T lymphocyte.
Cytotoxic T cells destroy target cells by prearranged apoptoses.
Following the information in the question regarding the difficulty in the biology lab that Warner wants to compete, if he doesn't complete, then he'll likely conform to others in this setting because the task seems difficult.
