Microscopic view of Shigella sonnei (Public Domain)


 Binary Fission
Binary fission is an asexual reproduction process used by prokaryotes. Before binary fission occurs, the DNA in the cell tightly coils up. Binary Fission (Public Domain)Next, the DNA in the cell replicates then the DNA is pulled to separate poles to prepare for the splitting of the cell. A new cell wall then starts to grow which in turn starts to separate the Shigella. Then the new cell wall develops completely and the Shigella cells are completely split. The new cells have tightly coiled DNA, ribosomes, and plasmids. The diagram above depicts the process of binary fission.


Shigella sonnei transfers DNA by a process called conjugation. Conjugation facilitates transfer of DNA from a donor to recipient. Conjuation in Shigella sonnei (Public Domain)Conjugation occurs when bacteria is passed through two joined prokaryotes. DNA moves from one cell to another but it can only move one way. The donor cell is the cell that starts with the DNA which is called the F factor. The receiver cell is the cell that receives the DNA from the donor cell but the receiver cell cannot already contain F factor otherwise the process will not work. Shigella cells will pass DNA through a sex pilus. The sex pilus joins the two cells together and pulls the cells very close together for the DNA transfer in the cytoplasm. DNA polymerase is synthesized then the DNA will move through the sex pilus from the donor cell to the receiver cell.

Positive and Negative Factors of Conjugation

The genetic transfer is beneficial to Shigella sonnei because it generates genetic recombination which then can be beneficial for antibiotic resistance and tolerance to chemicals. The only negative factor of conjugation is notShigella sonnei undergoing conjugation (Permission Granted) all bacteria can create sex pili but sex pili can form between many different bacterial species.

Infection of the Cells
All reproduction by Shigella sonnei is done when this bacteria enters the human intestine tract. It takes as few as 100 Shigella sonnei cells to start the infection within the human body. Once more of these bacteria cells are made, the infection starts to take effect on the body, which is only a matter of a day or two. The picture to the right depicts when the two sex pili come together and the donor is giving the receiver DNA.

Now that you know how Shigella sonnei reproduces, you should check out how this infection actually interacts with your body! GO!

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