Comparing Structural And Functional Characteristics Of Prokaryotic And Eukaryotic Cells

Please write an essay of approximately 1500 words, comparing structural and functional characteristics of prokaryotic and eukaryotic cells. You can illustrate your answer, where appropriate, with named examples and labelled diagrams. There's not much information in these slides about Prokaryotic Cells but about Eukaryotic Cells are there. 

Structural and Functional Characteristics of Prokaryotic and Eukaryotic Cells

Eukaryotic cell arose from prokaryotic cells about 1.8 billion years ago (Mclnemey, J, and Oconnel, M.2017). Thus both cells shear some features even though they have some distinct features that differentiate them, but before I explore prokaryotic and eukaryotic cells in detail, it is worth defining cells. It is a building/basic unit of life and all living organisms are made of cells.  Cells have the ability to divide and give rise to the new cell and self-correct (Plopper, G.2014). Therefore the existence of cell shows that it has developed from the preexisting cell. Cells are very tiny that cannot be seen with naked eye. As result of that if there was no discovery of electron microscope the difference between eukaryotic cells and the prokaryotic cell would be elusive to both researchers and biologist. The understanding of cell is important to understand prokaryotic and eukaryotic cells in terms of their structural and functional traits. However this essay will compare eukaryotic cells and prokaryotic cells with regard to their structures, their functions, features they share as well as the ones they don’t share and further explore the reasoning behind them.

Typical example of prokaryotic cell (bacterium)

(Retrieved from www.shmpoo.com)

Typical example of eukaryotic cell ( animal cell)

Retrieved from (Merchant, R, and Favor, L 2015)

Prokaryotic cells are cells that lack nucleus while eukaryotic cells that have the nucleus (Merchant, R.and Favor, L.2015).For instance, a bacterium serves the as good example of the prokaryotic cell while animal and plant cell as a eukaryotic cell(Routh, D.2006). In addition, eukaryotic cells have a membrane-bound nucleus which contains chromosomes and deoxyribonucleic acid (DNA) - a building block of life. Cells cannot be discussed in detail in isolation of organelles. They help the cell to perform its function and form the structure of the cell. They are just like organs in the body of living organisms i.e. heart in human's body (Merchant, R., and Favor, L. 2015), and for I that I turn to Nucleus. Controls all activities in the cell and participates in cell division (Routh, D .2006). In contrast, prokaryotic cells lack a nucleus. Instead, chromosomes spread in the cytoplasm. In prokaryotic cell, chromosomes are in direct contact with cytoplasm that is within the cell. In contrast, chromosomes are bound in a double-layered nucleus membrane in eukaryotic cells and its structure is complex compared to its structure in prokaryotic cells. Replication process of cells in the prokaryotic cell does not entail meiosis. However, cell division in a eukaryotic cell involves both mitosis and meiosis. The cell cycle in the prokaryotic cell is short compared to the eukaryotic cell. It takes roughly 20- 27 minutes and 12-24 hours to complete respectively. Even though both cells have cell membrane there is the difference in the structure of the cell membrane, for example, the phospholipid layer is universal in both cells but in the eukaryotic cell the membrane contains sterols that strengthen it while in the prokaryotic cell the membrane contains hepanoids which normally appeared spread all over the bacteria. In addition, the cell wall of the prokaryotic cell contains peptidoglycan- carbohydrate linked with protein while eukaryotic cell wall contains chitin- polysaccharide (Cecie, S.2009). In surface area to volume ratio. A prokaryotic cell has a large surface area to volume ratio. Thus they have high metabolic rate and growth while eukaryotic cells have small surface area to volume ratio thus, have low metabolic rate and growth compared to the prokaryotic cell(Barton 2005). Ribosomes: they help in translating information sent from DNA. In a eukaryotic cell, ribosomes are smaller and bit different in compositions and shape from the ones found in the eukaryotic cell. For instance, bacterial ribosomes have approximately half the quantity RNA and equator less ribosomal proteins more than ribosomes in eukaryotic cells. Despite these distinctions, the function of ribosomes remains the same in both cells as I have mentioned before. Another distinction between the two cells is that cytoplasmic movement occurs in a prokaryotic cell while in a eukaryotic cell there is no cytoplasmic movement. Furthermore, prokaryotic cells have mitochondria for example animal cell. They are sausage shape in structure and are the site for the respiratory reaction that yields energy from the cell. They have an inner projection (cristae) that increase the surface area of respiration, thus a lot of energy produced. In contrast, prokaryotic cells lack mitochondria. They depend on immediate surroundings to obtain energy (nature.com, 2018). They get energy from electron transport chain that is within their plasma membrane. 

Features Shared by Prokaryotic and Eukaryotic Cells

Both eukaryotic cell and prokaryotic cell have similar cell structures namely: cell membrane, cytoplasm and genetic material (deoxyribonucleic acid DNA) and RNA and flagella. Cell membrane: it separates the interior of the cell from external surrounding/ environment and has a double layer that made up of lipids- phospholipids. In both cell its control intake of substance in and out the cell and semipermeable in nature( can allow some substance to pass through  as well as prevent some substance to pass through) thus, the cell can allow or block some substances from accessing it from the surrounding fluid as well as excrete waste products to its environment. Gram-negative bacteria, for instance, have a double plasma membrane that has space in between them known as ‘periplasm’ and can withstand myriad of toxic substance and extreme environment. Also, prokaryotic cells have proteins stuck on the surface of a cell membrane that help them to communicate to the external environment i.e. receiving chemical signals from other cells especially in the process of infection and eukaryotic cell lacks such features. In addition, the cell membrane is extremely thin and measures about ten (10) nanometers in width. However, it is tough and flexible like elastic material. Cytoplasm: it is a gel-like fluid where other cellular components are suspended in a prokaryotic cell. However, in eukaryotic cells, the cytoplasm lacks organelles. Recently researchers discovered that prokaryotic cells have cytoskeleton similar to the one found in eukaryotic cells. Cytoskeleton

contribute to cell division in a prokaryotic cell, thus help the cell to maintains its shape (plump round shape) and responsible to cell contraction and motility. In contrast cytoskeleton in a eukaryotic cell, it is a framework where particles in the cell move around- ‘highway system’  and cell membrane. Cytoplasm is found inside the cell membrane, where most cell activities are carried out. It contains all organelles except nucleus and contains all chemicals that cell required. DNA controls the growth of cell and heredity of the cell. In prokaryotic cell DNA is in contact with cytoplasm- is not membrane-bound however in the eukaryotic cell it is in a membrane-bound nucleus. Finally both cells have flagella-hair like structure that protrudes from the surface of the cell. Prokaryotic cells have numerous flagella compared to eukaryotic cell (Cecie, S.2009).they help prokaryotic cell in locomotion and responsible for chemotaxis while in eukaryotic cells their function is not well defined. Plasma membrane: Both eukaryotic prokaryotic cells have a plasma membrane, a double lipid layer that separates the interior of the cell from external surrounding/environment.

Conclusion

From the forgoing, it is evidence that eukaryotic and prokaryotic cells are different, but some difference is not obvious that required a lot of keenness to identify. However, there is some distinct difference that is obvious: prokaryotic cells lack nucleus. In contrast eukaryotic cells have a nucleus; eukaryotic cells’ organelles are membrane-bound while in prokaryotic cells organelles are not enclosed in membrane. Finally Prokaryotic cells are small in size and eukaryotic cell big in size. Besides the existence of the conspicuous difference between the two types of cell, there are some features both cells shares e.g. plasma membrane, cytoplasm and deoxyribonucleic acid (DNA). This supports the argument of researchers and biologist who argued that eukaryotic cells originate from prokaryotic cells.in addition prokaryotic cell can  survive on their own compared to prokaryotic cell that that must get support from the body of plant or animals to survive. If they are separated they die. From the research I have done about the topic of this task, less books and articles give good insight of distinction between prokaryotic cells eukaryotic cells. Therefor more books and articles needs to be published concerning the topic above. 

References

BARTON, L. L. (2005). Structural and Functional Relationships in Prokaryotes. https://dx.doi.org/10.1007/b138652.

Biologist, 2018. Eukaryotic cell vs prokaryotic cells [online]. Available at.< https://www.diffen.com/difference/Eukaryotic_Cell_vs_Prokaryotic_Cell>[ Accessed4 April 2018]

 Biologist. Biology cell. [Online].[Updated 5 Feb 2011] Available at <http//www.shmoop.com/biology-cells/prokaryotic-cells.html > [Accessed 4 April 2018]

FAVOR, L. J. (2005). Eukaryotic and prokaryotic cell structures: understanding cells with and without a nucleus.

KARP, G. (2010). Cell and molecular biology: concepts and experiments. Hoboken, NJ, John Wiley.

McInerney, J.O. and O'connell, M.J., 2017. Microbiology: mind the gaps in cellular evolution. Nature, 541(7637), p.297.     

MERCHANT, R. G., & FAVOR, L. J. (2015). How eukaryotic and prokaryotic cells differ. https://alltitles.ebrary.com/Doc?id=11011975

PLOPPER, G. (2014). Principles of Cell Biology. Burlington, Jones & Bartlett Learning, LLC. https://public.eblib.com/choice/publicfullrecord.aspx?p=4441265.

ROUTH, D. (2006). Learning about cells. https://www.overdrive.com/search?q=AE211D2F-DDD9-4F16-A30A-41572B0942AA.

ROUTH, D. (2006). Learning about cells. https://www.overdrive.com/search?q=AE211D2F-DDD9-4F16-A30A-41572B0942AA.

Cecie, S. (2009). Biology: the unity and diversity of life. Belmont, CA., Brooks/Cole, Cengage Learning.

The biologist. Eukaryotic cells [online]. Available at:< https://www.nature.com/scitable/topicpage/eukaryotic-cells-14023963.> [accessed 4 April 2018