PY3002 Biology Foundation of Pharmacy
Demonstrate a fundamental understanding of the basics of biochemistry.
Identify and describe the structural and functional features of cells, tissues, organs and organ systems.
Demonstrate a fundamental grasp of a range of techniques used in modern biology; perform simple experiments, accurately record and analyse practical data.
Essay writing is a very important skill that you will use many times during your course and future career. It involves skills in research, writing, referencing, organising information and being critical. These are some of the skills that will distinguish you as a graduate from people who have no degree. Writing is a skill that you should see as fun and enjoy and develop for much of your life. Successful completion of this essay will demonstrate that you have many of the skills needed to complete and do well in the Foundation of Pharmacy.
Briefly summarise the similarities and differences between a compound light microscope and a transmission electron microscope.
To illustrate the differences between these two types of microscope, draw an animal cell as seen with a light microscope showing three labelled structures AND an animal cell seen with a transmission electron microscope showing five labelled structures which can ONLY be seen with the electron microscope.
Briefly discuss the techniques you have used in the laboratory to make structures more visible when viewed with a light microscope.
Explain the process of cell fractionation to extract specific cell organelles for biochemical study. What are the physical properties of the organelles that allow them to be separated?
Answer:
Introduction
The animal cell is the smallest unit of an organism. Animals have different types of cell structures and cell components. These cell structures are observed and studied using cell biology techniques. These techniques include microscope, staining techniques and Cell fractionation (Gennis, 2013, p6).
A microscope varies from each other with different sizes and it’s appropriate. The two common microscopes utilized in the observation of cell structures such as mitochondria are light and electron microscope. Both of these two types have different features which are suitable for different functions. Their similarities are that they both visualize small objects that cannot be seen by naked eye, both are utilized in research applications and both involve specimen preparations like staining, sectioning, and mounting. Besides, both light and electron microscope follow Abbe’s law while visualizing small objects (Pawley, 2010, p10).
Some of the differences between the two are that a light microscope is used to view both live and dead specimens whereas electron microscope is utilized to view only dead specimens as electrons that it uses can destruct living cells. Secondly, the resolving power for light microscope very low and is usually below 3 micrometers whereas electron microscope has a high-resolution power of up to 0.01 nanometers. The other difference between the two is that a light microscope utilizes light and glass lenses to view images whereas the electron microscope utilizes beam of electrons and magnetic lenses to view images (Gennis, 2013, p8).
Animal cell as observed under light microscope and electron microscope respectively
In order to keep animal cell structures alive, it is important that all biochemical and proteolytic processes are inactivated via a process known as fixation (Freshney, 2015, p3).There are two types of fixation which includes chemical and physical fixation approaches. The fixation is mostly used where tissues are immersed in fixative agents that kills and stabilizes the cell structures. Fixative agents used include ethanol, acetone and methanol. On the other hand, physical fixation involves microwaving and cryopreserving the samples in order to inactivate cellular activities and lower temperatures.
Staining refers to a technique that is utilized to enhance contrast and make objects visible while using a light microscope (Pease, 2013, p2). Stains and dyes are mostly used and aids in the examination of bulk tissues such as organelles, blood cells, and muscle fibers. Different types of staining techniques include simple staining, differential staining, and special staining. Simple staining involves coloration of microorganisms by applying either fixed smear or a single dye. Dyes used that are commonly used in simple staining in order to determine the size and shape of prokaryotic cells include methylene blue, carbolfuchsin, and crystal violet.
The second technique is differential staining which is utilized to distinguish microorganisms in relation to staining properties. The technique is more elaborate as cells are exposed to more than one dye, unlike simple staining technique. The third one is gram staining commonly used in differential staining techniques.
Cell fractionation refers to the process that involves disruption of cells and tissue to produce pure fractions of cell organelles. It involves three steps which include extraction, homogenization, and centrifugation. Extraction is the first step of cell fractionation which involves isolation of any sub-cellular structures (Rosner, Schipany and Hengstschläger, 2013, p5). The sub cellular structures are extracted in a mild environment which is referred to as cell-free systems in order to maintain their biological activity. These cell organelles are then suspended in a solution which has appropriate ph and salt content. The second step is homogenization which involves the step where suspended cells are disrupted via grinding, high pressure, sonication or osmotic shock (Freshney, 2015, p3).
The shearing force produced as a result of movement of cylinders leads to the rupture of cell organelles. The third step in cell fractionation is centrifugation which involves fractionation of various cell components carried out in a preparative ultracentrifuge (Gennis, 2013, p 7). The rate at which cell component settles down relates to its shape, size a term known as sedimentation coefficient. The physical properties that allow organelles to be separated include size, density, and shape.
Conclusion
In conclusion, one can study animal cells depending on the tools and techniques used. There are different types of techniques used in the study of animal cell. These techniques include microscope, staining techniques and Cell fractionation (Alberts et al., 2015, p80). Basic knowledge of these cell biology tools and techniques are required.
References
Alberts, B., Roberts, K., Lewis, J., Bray, D., Hopkin, K., Johnson, A.D., Walter, P. and Raff, M., 2015. Essential cell biology. Garland Science.
Freshney, R.I., 2015. Culture of animal cells: a manual of basic technique and specialized applications. John Wiley & Sons.
Gennis, R.B. ed., 2013. Biomembranes: molecular structure and function. Springer Science & Business Media.
Pawley, J. ed., 2010. Handbook of biological confocal microscopy. Springer Science & Business Media.
Pease, D.C., 2013. Histological techniques for electron microscopy. Elsevier.
Rosner, M., Schipany, K. and Hengstschläger, M., 2013. Merging high-quality biochemical fractionation with a refined flow cytometry approach to monitor nucleocytoplasmic protein expression throughout the unperturbed mammalian cell cycle. Nature protocols, 8(3), p.602.
