Cell Biology and Structure

This assignment delves into the world of cell biology, exploring its structure and function as the fundamental unit of life. It discusses various types of cells, including epithelial, secretory, muscle, and plant cells, highlighting their unique characteristics and roles in different processes such as excretion, transport, absorption, and more. The report also touches upon nerve cells, explaining how they transmit electrical impulses and convert chemical signals into small electrical signals.

Cell Biology

Table of Contents
INTRODUCTION...........................................................................................................................1
TASK 2............................................................................................................................................1
Different cells with structure and functions...........................................................................1
CONCLUSION................................................................................................................................6
REFERENCES................................................................................................................................7

INTRODUCTION
Cell biology refers to study of structure and functions of different kinds of cells along
with analysing the concept that it is a fundamental unit of life. It consist various types of cells
such as epithelial, secretory, muscle and specialised plant cells which has their own structure and
functions to body of organism (Pollard and et. al., 2016). The present is based on cell biology
and going to focus on different cells by defining their functions and structures.
TASK 2
Different cells with structure and functions
The cell can be explained as basic structural and functional unit of life including several
components which are known as organelles. It consist cell membrane, endoplasmic reticulum,
mitochondria, golgi apparatus, lysosomes, nucleus, cytoplasm, perioxisomes and microfilaments
& microtubules. Moreover, there are different types of cells containing their own structure and
functions but few of cells lack almost al organelles like red blood cells.
Epithelial cells
The epithelial cells cover all body surfaces which exposed to outside environment and
lining the outside organs. It also consist other areas including airways, digestive tracts, urinary
and reproductive systems which are lined by epithelial cells.
(Source: Epithelial Tissue, 2019)
However, the structure of epithelial cells contain less or no extracellular material with
between cell membranes known as cell junction. It consist basal lamina which is mixture of
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Illustration 1: Epithelial Tissue

glycoproteins & collagen render a connection site for epithelium and attaches to reticular lamina
that secreted by underlying connective tissues in order to form a basement membrane which
facilitate hold it all together. Epithelial cells consists different shapes and arrangements like
squamous, cuboidal & columnar epithelia (Strober, 2015). Moreover, the functions of epithelial
cells are protection from environment, coverage, secretion, excretion, absorption and filtration.
Meanwhile, these cells bound together by tight junctions and form impermeable barrier which
protect body from outside atmosphere. Additionally, they contain feature of polarity and
potentially separate harmful materials from airways and cuboidal epithelia are active in secretion
and absorption of molecules.
Secretory cells
The secretory cells and tissues are concerned with accumulation of metabolism by
products which are not used as reserve substances. It include the secretion sites of cells at plasma
membrane which are known as porosomes where secretory vesicles transiently dock and fuse
that results into release of intra-vesicular contents from the cell.
(Source: Secretory cells, 2016)
The functions include that intestinal epithelium contains specialised cell lineages
including absorptive enterocytes and secretory enteroendocrine, Paneth & goblet cells. However,
parietal cells secret hydrochloric acid and chief cells release digestive enzymes like pepsin.
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Illustration 2: Secretory cells

Moreover, serous cells are responsible for secreting watery fluid, necessarily devoid of mucus
whereas mucous cells release a very mucus rich secretion (Nikolayeva and Robinson, 2014).
Muscle cells
The muscle can be considered as myocyte which consist an ability to shorten itself by a
series of motor proteins and it contain nucleus, which are pressed against cell membrane.
However, muscle cells is formed by compact bundle of many myofibrils containing sarcomeres
and a specialised form of endoplasmic reticulum (ER) is called as sarcoplasmic reticulum (SR)
which extends it around the myofibril bundles.
(Structure of a Muscle Cell, 2018)
Moreover, sarcoplasmic reticulum is activate by signals of nerve cells to contract and
become short (Takasato and et. al., 2014). In addition to this mitochondria remain densely
packed with muscles cells in order to provide energy as ATP. Meanwhile, the signals travels
through transverse tubules (i.e. T tubules) to activate SR and the entire cell is covered by special
cell membrane which is known as sarcolemma. The main function of muscle cells is to facilitate
the muscle contractions in which thin & thick filaments slides with respect of utilising energy as
ATP. It contains different types of contractions such as twitch, treppe, tetanus and
isometric/isotonic.
Specialised plant cells
The plant cells can be considered as eukaryotic cells which are divided into several types
such as parenchyma, sclerenchyma, collenchyma, xylem and phloem with specific functions.
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Illustration 3: Structure of a Muscle Cell

Initially, parenchyma cells prepare leaves and plays important role of metabolism and food
production. Secondly, sclerenchyma cells are hard and provide support to plant as it exists in
roots.
(Source: Dicot stem anatomy, 2019)
Thirdly, collenchyma cells help plant to grow and stretch along with providing support
when plant is young. However, xylem cells are considered as water conducting cells including
bring water to leaves. Moreover, phloem cells which is responsible for transporting sugar
produced in leaves within whole plant (Levitan and Kaczmarek, 2015).
Red blood cells
The red blood cells (RBCs) are also considered as erythrocytes which consist shape of
biconcave disc with diameter of 6 to 8 μm and average thickness is approximately 2 μm. The
main function of RBCs is to transport oxygen within whole body by utilising haemoglobin and
also facilitate to control the pH of blood through preparing an acid-base buffer in order to
maintain neutral pH at 7.35 to 7.45. Meanwhile, RBCs also secrete an enzyme named as
carbonic anhydrase that cause water in lungs for carrying carbon dioxide to lungs so that it can
be expelled out from the body.
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Illustration 4: Dicot stem anatomy

(Source: Erythrocytes and lymphocyte, 2019)
Nerve cells
The nerve cells are also known as neurons which are responsible for conducting an
important function to transmit information throughout whole body in form of electrical signals or
nerve impulses. However, the structure of neurons consist cell body, dendrites, axon and axon
terminals. Moreover, cell body contain nucleus to synthesize neural proteins and axons conduct
electrical impulses in form of action potentials.
(Source: Nerve cell, 2003)
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Illustration 5: Erythrocytes and lymphocyte
Illustration 6: Nerve cell

Moreover, nerve cells consist multiple dendrites which make them multipolar, bipolar or
unipolar that convert chemical signals from the synapse into small electrical signals impulses and
transmit them towards the cell body.
CONCLUSION
The above report conclude that cell biology can be described as to study their structure
and functions and it is known as fundamental unit of life. It consist various kinds of cells such as
epithelial, secretory, muscle and plant cells which plays their own function due their specified
structures including excretion, transport, absorption and many more.
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REFERENCES
Books and journals
Pollard, T. D. and et. al., 2016. Cell Biology E-Book. Elsevier Health Sciences.
Levitan, I. B. and Kaczmarek, L. K., 2015. The neuron: cell and molecular biology. Oxford
University Press, USA.
Strober, W., 2015. Trypan blue exclusion test of cell viability. Current protocols in immunology.
111(1). pp.A3-B.
Nikolayeva, O. and Robinson, M. D., 2014. edgeR for differential RNA-seq and ChIP-seq
analysis: an application to stem cell biology. In Stem Cell Transcriptional Networks (pp.
45-79). Humana Press, New York, NY.
Takasato, M. and et. al., 2014. Directing human embryonic stem cell differentiation towards a
renal lineage generates a self-organizing kidney. Nature cell biology. 16(1). p.118.
Online
Secretory cells. 2016. [Online]. Available through:
<http://www.siumed.edu/~dking2/erg/gicells.htm>
Structure of a Muscle Cell. 2018. [Online]. Available through:
<https://biologydictionary.net/muscle-cell/>
Epithelial Tissue. 2019. [Online]. Available through:
<http://anatomyandphysiologyi.com/epithelial-tissue/>
Dicot stem anatomy. 2019. [Online]. Available through:
<https://www.plantscience4u.com/2013/03/dicot-stem-anatomy.html#.XEagZnUzbqN>
Erythrocytes and lymphocyte. 2019. [Online]. Available through:
<https://www.majordifferences.com/2014/04/difference-between-erythrocytes-
and.html#.XEbThXUzbqM>
Nerve cell. 2003. [Online]. Available through:
<http://www.siumed.edu/~dking2/ssb/motoneur.htm>
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