Cell Biology Assignment: Discoveries in Nerve Cell Function

This assignment explores two Nobel Prize-winning discoveries in cell biology. The first, from 1963, recognized the work of Sir John Eccles, Andrew Huxley, and Alan Hodgkin on ionic mechanisms in nerve cell membranes, explaining how action potentials are initiated and propagated. Their research highlighted the importance of ion channels for transmitting nerve impulses and sensory perception. The second discovery, from 1994, awarded to Alfred Gilman and Martin Rodbell, focused on G-proteins and their role in cellular signal transduction, revealing how cells communicate using hormones and signaling molecules. They discovered that G-proteins act as signal transducers, amplifying signals and regulating cellular responses. These discoveries have significantly advanced our understanding of nerve function and cellular communication, paving the way for treating medical conditions related to impulse transmission.

Running head: CELL BIOLOGY 1
Cell Biology
Name
Date of Submission

CELL BIOLOGY 2
1963
The Nobel prize in 1963 was awarded collectively to Sir john Eccles, Andrew Huxley
and Alan Hofgkin. These scientists made discoveries about ionic mechanisms in the excitation
and inhibition in central and peripheral parts of the nerves cell membrane. This discovery
explained how action potentials in the neurons can be initiated and propagated. An example is
the calcium ions which are termed as second messengers whereby the concentration in the
cytosol is low due to the ATP powered pumps that are involved in calcium ions transport outside
the cells. In the nerves, when the calcium ions concentration in the cytosol increases, there is the
exocytosis of the vesicles containing the neurotransmitters (Jones & Smith, 2016). These three
scientists thus made the scientific community understand that for nerve impulses to be
transmitted, the opening of the ion channels is very important. This is because nerve impulses
facilitate the sensory perception of various stimuli on the environment by the brain. Therefore,
when a nerve impulse is being transmitted, there is the opening and closing of ion channels
which creates membrane potential of the nerve cells. An increase in calcium ions concentration
is regulated by sensors known as the calcium-ions binding proteins such as calmodulin.
Since the nerves work like several microscopic generators, when there is a stimulus, the
nerves fire electrical impulses repeatedly. Thus Andrew Huxley and Alan Hofgkin made a
revelation of the triggers which fire the in-built electrical system of nerves. They used the giant
nerves fibers of squid which are thicker than the human nerves. On taking measurements, it was
found that the electrical difference from the inside and outside never dropped from negative to
zero during impulse transmission, but instead, the potential became positive. It was concluded
that changes in cell membrane permeability allows the flow of charged atoms in and out of nerve

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fibers (The Nobel Prize in Physiology or Medicine, 1963). During a nerve impulse, positive
sodium ions get inside from outside while in the falling of the impulse, the potassium ions get
outside. Then John Eccles further explained the works of Hodgkin and Huxlexy during
transmission of impulses from one nerve to another.
1994
The Nobel prize in physiology or medicine in 1994 was given to Alfred Gilman and
Martin Rodbell for their discovery of the G-proteins and their role in cellular signal transduction.
This discovery explained that cells communicate with other cells using hormones and other
signaling molecules. When the G-proteins bind to guanosine triphosphate, they act as signal
transducers that transmit and modulate impulses (Vauquelin & von Mentzer, 2007). These
proteins receive several signals from exterior of the cells and activates them through
amplification so that they regulate various cell responses. These two scientists argue that the
signal binds to its receptor. Then the amplifier or G-protein generates the second messengers
such as the cyclic AMP. Rodbell discovered that this transducer is powered by guanosine tri
phosphate. Later on, using leukemia cells, Gilman found that mutated cells lack transducer
functions ("Physiology or Medicine, 1994). Then Gilman and Rodbell purified some proteins
from normal cells that can be put in defective cells via membranes and restore the cell functions.
This created a paradigm shift in physiology or medicine since it reveals that there are two
distinct pathways of impulse transmission, either within nerves or across cells. At the moment,
such discoveries have made it possible to treat medical conditions arising from improper impulse
transmission by restoring back default cells and nerves at the cell membrane regions.

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References
Jones, B. L., & Smith, S. M. (2016). Calcium-sensing receptor: a key target for extracellular
calcium signaling in neurons. Frontiers in physiology, 7, 116.
Physiology or Medicine, (1994). Press Release. Nobelprize.org. Nobel Media AB 2014. Web. 5
May 2018. Retrieved
http://www.nobelprize.org/nobel_prizes/medicine/laureates/1994/press.html>
The Nobel Prize in Physiology or Medicine, (1963). Speed Read: Signal to Charge".
Nobelprize.org. Nobel Media AB 2014. Web. 4 May 2018. Retrieved from
http://www.nobelprize.org/nobel_prizes/medicine/laureates/1963/speedread.html
Vauquelin, G., & von Mentzer, B. (2007). G Protein‐Coupled Receptors. G Protein-Coupled
Receptors: Molecular Pharmacology from Academic Concept to Pharmaceutical
Research, 77-230.