May 21, 2024

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How Cells Divide: What Mitosis And Meiosis Really Are

To duplicate itself any mother cell has two choices, cell division or cytoplasm division, no mitosis or meiosis is involved in this process. What makes a difference between prokaryote and eukaryote cells is that the later take more time to prepare for new cell production than the more primitive prokaryotes. Please read on to find out why this is so!

Life goes in steps or stages or phases bound in what is called a life cycle that is followed by all living organisms from generation to generation.

For prokaryotes the life cycle or the cell cycle has 4 phases:

The first growth phase called G1 is characterized by a single genetic center, here the nucleoid

The phase S where there is DNA synthesis, doubling the amount of DNA inherited at birth. Since most of the time prokaryotes have only one big circular DNA molecule (sometimes associated with very small ones), after this synthesis is completed we will have two DNA molecules of the big type.

The second-growth phase, G2, is the one where there are two DNA molecules in the cell that prepare to divide into two smaller new cells.

The cell division phase allows the cell to manage to produce two new smaller cells. The mother cell just divided has disappeared in the process but without leaving any trace of its former existence.

Prokaryotic cells designed two ways to divide themselves into tow new cells:

The real cell division where the mother cell is cut into two separate whole cells which can stay together if they cannot move by themselves or move in different directions when they have means to do so (bacteria with flagellum or cilium). It is amazing that this true cell division in moving cells is called scissiparity, as if it were a different way some cells divide. This needs to be corrected too.

The cytoplasmatic division within the mother cell, without separation of daughter cells which are bound together through the sharing of one part of their outer envelope. This leads to filamentous forms in some blue-green algae (like oscillaria) and in some bacteria.

So, a prokaryotic cell has two choices when it comes to cell division. According to its nature it can go true cell division or cytoplasmic division. But only a cell with two nucleoids (two separates molecules of DNA) can divide as to give one whole set of genetic information to each daughter cell. Without the whole genetic information, no living organism, whether it is a cell or a more complex organism, can live a long life. That is why it is important to a cell born with just one nucleoid or one DNA molecule to go through DNA synthesis in S stage before thinking about dividing itself, to ensure that each daughter cell will have her heritage.

Eukaryotic cells divide the same two ways like prokaryotes, only after they have two nuclei!

The life cycle of eukaryotic cells has five phases instead of four for the prokaryotic ones. After the phases G1, S and G2, they must go nucleus duplication before they can divide. That is where mitosis and meiosis come in.

They are well known and well described in biological books but most of the time they are associated with cell division in a whole process. What mitosis and meiosis really do is they allow eukariotic cells to duplicate their nuclei before they become able to divide if they are born with just one nucleus. They have only four well known phases that are prophase, metaphase, anaphase and telophase, period. After a cell is done with doing mitosis or meiosis, it has two new nuclei it can use different ways and cell division is just one of these ways!