Essay/Term paper: The language of the cell

Essay, term paper, research paper:  Science Reports

The Language of The Cell


MAY 3rd, 1996
SCIENCE 10 AP

The cell is a complex and delicate system: It can be seen that the cell
is the stage where everyday functions such as molecule movement, protein
synthesis and tissue repair take place. All organelles within the cell are well
rehearsed in their operations, but an error on an organelles behalf, can send
the cell and it"s organelles into panic. The efficiency rate of the cell
plummets down to a low level. It does take some time for the dust to settle,
and once the scripts are memorized, the cell is now ready to begin it"s tasks
again.
Since the 19th Century, it was known that all living things, whether
they were plants or animals, were made up of cells. This whole idea has been
given credit to an English Physicist, Robert Hook (1635-1703), when he looked at
a thin slice of cork under powerful hand lens. Hook discovered a large number
of cells. Rudolf Virchow (1821-1902) propounded this idea, that the cell is a
basic structure and functional unit for all living organisms.
A cell can be a wide range of shapes and sizes, although most cells are
microscopic. Inside a cell membrane, a nucleus can be seen. The nucleus is the
control center of the cell. Between the nucleus and the membrane, there is a
polysaccharide matrix called the cytoplasm, where organelles can be found. The
organelles are attached to a framework. The cell"s cytoskeleton.
Every living cell has the ability to detect signals from it"s
environment. The signals are usually in the form of chemical molecules, that
the cell has learned to recognize. The cell decodes these molecules into
messages, and acts upon them. The cell has a "language". Signals and messages
are carried by particles of matter that have a very low energy requirements.
There are many, many signals rumbling around the cell. It was thought that the
cell would confuse itself in all of that background signal noise. One defense
is available to this question. The cell"s decoding mechanisms are located
downstream from the receptors. They are based on complex chemical reactions
that take place in the cell membrane and control all the responses of the cell
to the messages it receives.
Neuropeptides and polypeptide hormones, are made up of complex
assemblies of amino acids, aligned in different sequences. In other cases, the
amino acids are slightly transformed, as this is the case with well known
transmitter substances such as epinephrine (adrenaline), dopamine and histamine.
Products made in the organelles within the cell, are sent to various
destinations, both in and out of the cell. The cell has what amounts to a
parcel delivery service, that is guided by "addresses," by chemical "tags" or
labels. These labels generally consist of fairly simple molecules (often
sugars) attached to the product being forwarded and recognized by the structure
for which it is intended.
When a cell messes up on a delivery, which doesn"t happen very often, is
usually the result of a genetic defect. The "tag" on the product being
forwarded is usually mutated, therefore the receptor cannot recognize it.
Sometimes, the receptor is mutated, meaning that it does not recognize the
signal. The result of this is a botched cell. An example of this is a low
density lipoprotein receptor. If the lipoprotein fails to sequester and
internalize it"s signal (cholesterol), then cholesterol can no longer be
reincorporated in the cell, and it builds up in vessels, causing potentially
fatal conditions.
Three recent discoveries about the cell tell us that;

A) Each cell is not simply controlled by an accelerator and an inhibitor, and
the cell has the ability to recognize a great amount of signals. B) The number
of signals discovered in the body has increased tremendously. C) Signals within
the cell are not, as formerly believed, characteristic of an organ or function,
but they are all found in nearly all organs and are associated with nearly all
functions.

As mentioned earlier, signals are incredibly small, have low energy
requirements and weigh approximately one billionth of a gram. Scientists have
discovered new signals with the development of extremely effective chemical
methods that make it possible to purify them and elucidate their structure.
These advances and discoveries lead to a well understood field of protein
chemistry. One problem is that new signals are coming out everyday!
A point which should be stressed is that the universality of
communication implies that no signals are attached exclusively to one organ or
function. However, signals do not circulate unrestrictedly throughout the body.
Most signals are very versatile in the way that they can carry out all sorts of
assignments whether it be local cell to cell communications or long distance
cell to cell communications. The best example of this is epinephrine, which
acts both as a nervous system mediator and as a hormone.
On the contrary, some signals remain highly specialized, and therefore
cannot take on many of the tasks that a versatile signal can. GnRH, a small
peptide of amino acids, is mainly involved in the regulation of sexual behavior,
reproductive hormones and external genital organs. These highly specialized
organs can be found in a select amount of organs only.
All cell"s and organs depend heavily on the receptors and decoders
ability to do their job. Recognition errors by the mechanisms in the immune
system can have grave consequences: unintentional destruction of elements of
the self, failure to be alert to nonself antigens. The cells responsible for
the body"s defenses use different decoding combinations for protection. Example
is that a foreign antigen is perceived foreign only if it is presented to the
lymphocyte (white blood cell formed in lymphoid tissue) by another cell. The
cell"s crash-free system calls for one more security check. Appropriate signals
have to "confirm" the order to respond to the intruding antigen by the secretion
of antibodies. Fail safe? The reader definitely hopes so.
Neuroendocrinolgy. A nice long name for an extremely important field of
study. Neuroendocrinology is the study of the exchanges of signals, and how
they are integrated in the general coordination plan of an organ. A cooling of
the outside temperature perceived by the nervous system"s sensory organs
triggers an increase the production of heat and at the same time a decrease in
it"s dissipation. The same goes for when it is hot outside, the sensory organs
order a decrease in heat production and the dissipation rate is raised. The
steps the cell go through, are similar to that of the thermostat. Both
responses involve concomitantly nervous mechanisms (changes in behavior,
chilling, etc...) and a hormonal link; stimulation of the thyroid. This is an
example of a neuroendocrine reflex. It is interesting to note how a thermostat
can be related to a neuroendocrine reflex. Home device ideas "taken" from
bodily functions may turn out to be a useful tool in the school curriculum.
Students could relate various abstract concepts to everyday household devices.
Their is an old question of the relation between the simplicity and
complexity in biology. During the course of evolution, rules about the theory
of cell communication has more or less remained unchanged. A primitive
organism; a bacterium or an amoeba, when directly immersed in a liquid medium,
fulfill the need for securing information regarding their environment. What are
the available nutrients? The unicellular organism decodes this information and
acts upon it. If their are food signals, then the amoeba will undergo
phagocytosis, capture the food and then enzymes will be released and the food
will be digested. The cell and it"s signals is a continuing circle.
The reader thought that the Language of the Cell was an extremely hard,
well written book. The book went deep into the subject most of the time, and
sometimes the reader found this confusing. One negative point discovered by the
reader was that the concepts explored in the book were new, confusing and
frustrating. Little was understood on neurology, yet the reader made an
incredible effort in trying to understand, and make sense of the topic. The
reader feels that there are not many books that have to deal with biology on a
grade ten AP level. Therefore, a reading assignment of this sort can be
extremely challenging, and leave the reader with too many questions and no
answers. The reader feels that these kind of book report assignments should be
explored in grade twelve, when DNA and other neurological concepts of some sort
are known.
The reader felt that this whole book report was an experience, and it
broadened the reader"s knowledge base. The reader also found out that biology
is a very interesting subject as a whole, but some fields of study under the
whole biology picture are extremely boring and complicated. Maybe this
impression will change over time.


BOOK INFORMATION

LIBRARY: Fish Creek Area Library NAME OF BOOK:
The Language of the Cell AUTHOR: Claude Kordon
PUBLISHER: McGraw-Hill, Inc. PUBLICATION DATE: 1993 CALL
NUMBER: 3 9065 03969 1246 DUE DATE: May 3rd,
1996