B Cell division: Cell cycle, Mitosis, Meiosis and their Significance

Introduction

B cells, commonly called B lymphocytes, are a lymphocyte subtype of white blood cells. They are a part of the adaptive immune system’s humoral immunity component. Antibody molecules are produced by B cells, however, they are not released. Rather, they are introduced into the plasma membrane and function as B-cell receptors. When an antigen activates a naive or memory B cell, it proliferates and develops into a plasmablast or plasma cell, an antibody-secreting effector cell. Let us further explain the B Cell division in detail with cell cycle, mitosis, meiosis and their significance.

The Cell Cycle of the B Cell

• The cell cycle is a series of activities that occur over and over in a cyclical manner, including development, DNA synthesis and division of cells
• In prokaryotes, the cell cycle is straightforward: the cell grows, its DNA repeats and the cell splits. Asexual reproduction is the name for this type of division in prokaryotes
• The cell cycle in Eukaryotes is more intricate. There are multiple stages to the eukaryotic cell cycle. Mitosis and cytokinesis are both parts of 1st phase, known as the mitotic phase (M). The nucleus first and later the cytoplasm split at this point. The remaining three phases (G1, S, and G2) are classified as interphase
• The cell matures, goes through its normal life activities, and starts to divide during interphase
• These Interphase stages are further subdivided as follows
•  Growth Phase 1 (G1): The cell spends the majority of its life in G1, the first gap (also known as growth) phase. A cell grows rapidly and performs its normal duties during this phase. The cell’s biosynthetic and metabolic activities are active at a high pace during this period. During this phase, the cell’s requirements for amino acids and proteins are met. Among the proteins generated are those required for DNA replication. From this phase, if a cell doesnt split, it enters the G0 phase
• The G0 phase- is just a resting stage in which the cell has exited the cycle and has ceased to divide. In multicellular eukaryotic organisms, non-dividing cells go from G1 to G0. These cells, like neurons, can stay in G0 for lengthy periods of time, even indefinitely. Completely differentiated cells can also go into the G0 phase. When the viability or sustainability of their daughter cells is threatened, such as by DNA damage or degradation, certain cells stop dividing, the process being known as cellular senescence. Normal diploid cells lose their ability to divide after around 50 cell divisions, resulting in cellular senescence
• Synthesis Phase (S): Beginning in G1, dividing cells enter the Synthesis (S) phase. The cell’s DNA must be duplicated through DNA replication to produce two identical daughter cells. Both strands of the double helices are utilised as templates to create two new complementary strands when DNA is duplicated. Two double helices are formed when these additional strands of hydrogen bind to the template strands. The amount of DNA in the cell has essentially doubled during this phase, though the cell remains diploid
• The second gap (growth) phase (G2)- is a shorter stage of growth during which numerous organelles are replicated or synthesised. During G2, components for mitosis and cell division, such as microtubules for the mitotic spindle, are produced

• Mitotic phase

1. Mitosis is the initial step in a eukaryotic cell’s mitotic phase, a multi-phase procedure in which the cell’s nucleus divides. The nuclear membrane breaks down during mitosis and then reforms. To guarantee that each daughter cell has a complete set of chromosomes, the chromosomes also are sorted and separated.
2. Cytokinesis is the next major phase. The cytoplasm divides and two daughter cells develop in this step, which also occurs in prokaryotic cells.
3. At this point, cell growth comes to a halt. The nucleus is divided into two nuclei during mitosis, while the cytoplasm is divided during cytokinesis. As a result, two identical daughter cells are produced.

Mitosis and Meiosis:

In mitosis, a cell’s genetic material (DNA) doubles and divides evenly between two cells. Following that, the dividing cell would go through the cell cycle, which is a structured sequence of activities. The mitotic cell cycle is also initiated by the presence of particular growth factors or other signals indicating the need for new cell formation. Mitosis also allows the body’s somatic cells to reproduce.

Meiosis is the procedure by which gametes, sex cells, are produced in sexually reproducing organisms.As you may know, gametes are produced in both male and female gonads and have half the amount of chromosomes as the originating cell. Furthermore, the genetic recombination that occurs during meiosis, aids in the introduction of new gene combinations into a population. As a result, the meiotic cell cycle creates four genetically distinct cells rather than the two genetically identical cells produced by mitosis.

Conclusion 

The cell division cycle is divided into four periods: G1, S, G2, and M (mitosis). In rapidly proliferating adult cells, the cell cycle typically lasts 10 to 20 hours, but it can be stopped for weeks or months in quiescent cells or for a  lifetime in brain neurons. This form of extended stop usually happens during the G1 phase and is referred to as G0. Some embryonic cells, like those found in fruit flies (vinegar flies), can finish a cycle and divide in as little as 11 minutes. G1 and G2 phases are impossible to detect in these rare cases, and DNA synthesis alternates with mitosis. Moreover, the length of the S phase varies greatly. The DNA replication time of a fruit fly embryo is barely four minutes, compared to many hours in adult cells of the same species.