In life’s hierarchy, cells make up the lowest level of organization. Cells can perform activities required to sustain life. A cell’s ability to divide to form new cells is the basis for growth and repair in organisms. Cells also play a key role in the recycling of carbon, a chemical element essential to life, and also participate in cellular processes such as photosynthesis. With these points in mind, it should be noted that cells come in one of two forms: prokaryotic and eukaryotic. By investigating the structural and functional similarities and differences of prokaryotic and eukaryotic cells and by exploring the process of endosymbiosos, one can gain further insight into the diversity of cells. One distinct difference between these cells is prokaryotic cells can be classified as either bacteria or archaea while eukaryotic cells make up all other forms of life including plants and animals. This distinction arises from the fact that prokaryotic cells are simple, small, and mostly unicellular whereas eukaryotic cells are more complex, big, and generally multi-cellular. Eukaryotic cells have a membrane enclosed nucleus and many small organelles in its cytoplasm while prokaryotic cells lack membrane enclosed organelles of specialized form and function and a nucleus. Furthermore in a prokaryotic cell, DNA is not separated by a membrane bound nucleus; instead the DNA is concentrated in a region called the nucleoid. Another difference involves the way in which both the cells replicate. Prokaryotic cells reproduce through a process of cellular division known as binary fission. In binary fission one copy of the origin moves rapidly towards the other end of the cell. Once the origins meet on one side of the cell, the plasma membrane grows inward and a new cell wall is deposited. The result is two daughter cells. Eukaryotic cells reproduce through an evolved form of binary fission known as mitosis, in which spindles from outside the nucleus and break down into two separate cells, and meosis. Despite these major differences, both Eukaryotic and Prokaryotic cells have many structural and functional similarities. All cells are enclosed by a plasma membrane, filled with cytoplasm, that functions as a selective barrier. This barrier allows for the passage of oxygen, nutrients, and wastes between the cell and its surroundings. Another similarity is that both types of cells have chromosomes, ribosomes ( tiny organelles that make proteins via instruction from the genes) and protein lipids in their membranes. Both also have DNA strands which hold their genetic information. The evolutionary relationship between the both cells establishes how eukaryotic cells evolved from prokaryotic cells. Eukaryotic cells were created through a process of genetic exchanges between prokaryotes. This process is known as endosymbiosis. Two organelles which have directed this theory are the mitochondria and the plastids. Both of these organelles are found in eukaryotic cells however research has shown that these structures are decedents of independent prokaryotic cells. Since Eukaryotic cells have the ability to engulf other cells, it can be concluded that the prokaryotic ancestors of the mitochondria and plastids gained entry into the eukaryotic cells which in turn formed into packages of vesicles. Thus, Eukaryotic cells were
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