PY3002 Biology Essay: Techniques for Studying Animal Cell Structures

This essay provides an overview of the techniques used to study the structures of animal cells. It discusses microscopy, including light and electron microscopy, highlighting their similarities and differences in visualizing cell structures. The essay also covers specimen preparation, specifically fixation methods, and staining techniques like simple, differential, and Gram staining. Furthermore, it explains cell fractionation, detailing the steps of extraction, homogenization, and centrifugation used to isolate cell organelles. The essay emphasizes the importance of understanding these cell biology tools and techniques for studying animal cells.

TECHNIQUES USED TO STUDY STRUCTURES OF ANIMAL CELL 1
TECHNIQUES USED TO STUDY STRUCTURES OF ANIMAL CELL
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TECHNIQUES USED TO STUDY STRUCTURES OF ANIMAL CELL 2
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).

TECHNIQUES USED TO STUDY STRUCTURES OF ANIMAL CELL 3
Animal cell as observed under light microscope and electron microscope respectively
Image source (Gennis, 2013,p8).
Image source (Gennis, 2013, p8).
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.

TECHNIQUES USED TO STUDY STRUCTURES OF ANIMAL CELL 4
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

TECHNIQUES USED TO STUDY STRUCTURES OF ANIMAL CELL 5
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.

TECHNIQUES USED TO STUDY STRUCTURES OF ANIMAL CELL 6
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.