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Question
Naive B-lymphocytes are present in which of the following phase of the cell cycle?
Naive B-lymphocytes are present in which of the following phase of the cell cycle?
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Solution
The correct option is D G0
A cell cycle is a series of events that takes place in a cell as it grows and divides. The cell cycle consists of four discrete phases as follows :
- G1 phase (gap 1 phase) - It shows the end of cell division in mitosis and the beginning of DNA replication during S phase.
- S phase (synthesis phase) - DNA replication occurs in this phase.
- G2 phase (gap 2 phase) - It is a period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis.
- M phase (mitosis phase) - Cell division occurs in this phase.
When a cell is not dividing it is in G0 phase (the resting stage).
Once it decides to divide it enters the cell cycle.
Naive lymphocytes are not challenged by an antigen, thus they are in the resting stage. Hence option a is correct.
Once a B-cell encounters an antigen that binds to its membrane-bound antibody, it causes the cell to divide rapidly and differentiates into plasma cells and memory cells.
The plasma cells are short-lived and responsible for the secretion of soluble antibodies which are major molecules of humoral immunity while memory cells express the same antibody as their parent B-cell and help in secondary immune responses (immune response during subsequent encounter with the same antigen).
Figure : Formation of plasma cells and memory B cells
A cell cycle is a series of events that takes place in a cell as it grows and divides. The cell cycle consists of four discrete phases as follows :
- G1 phase (gap 1 phase) - It shows the end of cell division in mitosis and the beginning of DNA replication during S phase.
- S phase (synthesis phase) - DNA replication occurs in this phase.
- G2 phase (gap 2 phase) - It is a period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis.
- M phase (mitosis phase) - Cell division occurs in this phase.
Once it decides to divide it enters the cell cycle.
Naive lymphocytes are not challenged by an antigen, thus they are in the resting stage. Hence option a is correct.
Once a B-cell encounters an antigen that binds to its membrane-bound antibody, it causes the cell to divide rapidly and differentiates into plasma cells and memory cells.
The plasma cells are short-lived and responsible for the secretion of soluble antibodies which are major molecules of humoral immunity while memory cells express the same antibody as their parent B-cell and help in secondary immune responses (immune response during subsequent encounter with the same antigen).
Figure : Formation of plasma cells and memory B cellsSuggest Corrections
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