The 2013 Nobel Prize in Physiology and Medicine was awarded to James Rothman, Randy Schekman and Thomas Südhof for the work that they did on transport vesicles within the cellular membrane. The recipients discovered how the cellular transport system was organized so that transport material was delivered to the correct site with proper timing. Rothman discovered how the vesicle is able to fuse with a cell membrane or organelle to deliver its contents. Schekman through the study of yeast isolated the genes required to code for vesicle transport. Südhof found the signals that tell vesicles when to release their contents.
Schekman studied the cellular transport of system of yeast and documented his discoveries in his 1990 paper Distinct sets of SEC genes govern transport vesicle formation and fusion early in the secretory pathway. The key disocevery that was made is that in yeast there are seven genes that code for cellular membrane transport between the endoplasmic reticulum and the Golgi apparatus. It was also found that if temperatures became to high or to low, it would lead to a build up of vesicles at key locations, and prohibit cell transport. When the temperature became to hot class I genes would cause a change in the organelle and cell membranes that would not allow vesicles to bind to target sites, so they could carry out their protein transport. To correct this a class II gene would need to come in and consume the build up of vesicles at target sites to complete the cellular transportation. The combination of class I and II genes allow for proper and timely vesicle transport.
In Rothman's paper, SNAP receptor implicated in vesicle targeting and fusion his research led him to discover that the N-ethylmaleimide sensitive ...
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...ed to be present in order to promote a vesicle to bind to target sites. Rothman discovered that the NSF protein complex, which needs to present in order for vesicles to bind, is interchangeable with the SEC18 gene previously discovered by Schekman through research on yeast cells. Rothman also found a derivative of SNAP proteins, called SNAREs that enhance the ability of vesicles to bind to target sites. Südhof who discovered that increases in Ca2+ contributed to precision and correct timing in vesicle bidding later proved Rothman’s research in that SNARE proteins were needed in order for vesicles to properly bind to target membranes. In conclusion the work that each Laureate did individually, greatly advanced the understanding of cellular transport, however it is when their work is combined that the organization and procedure of cellular transport is made clear.
The cells are held together by regions known as intercalated disks. These overlapping, finger-like extensions of the cell membrane contain gap junctions and desmosomes. Gap junctions are protein-lined tunnels which allow currents to travel from cell to cell to ensure the cells contract in unison. Desmosomes are known for holding the Heart Cells together during a contraction. This is induced by the sliding of the cardiac
Receptor tyrosine kinase is a cell membrane receptor system that can trigger multiple cellular responses simultaneously. It requires two receptor tyrosine kinase proteins, which are initially individual polypeptides that each have a signal-binding site, an α helix spanning the cell membrane, and a tail of multiple tyrosines. When signal molecules bind to both proteins they attach through a process called dimerization, forming a dimer. This process activates, or phosphorylates, the ends of the tyrosines, also known as tyrosine-kinase regions. Once the dimer is activated, multiple inactive relay proteins are able to bind to the tyrosine-kinase regions. Each of these proteins trigger a cellul...
...s to interfere with bonding to the receptors. The final possibility uses CNP, which downregulates the activation in MAP kinase pathways in the chondrocytes (4).
It is also interesting to know just how many medical breakthroughs came about by accident. It allows people to realize that, although it should be handled with the utmost care, cut of the edge research is not always cut and dry. This book teaches that it takes true intellect to take what seems like a failure or an accident and instead of abandoning it, reflecting on what has truly happened. Students as well as current researchers should read, study, and take inspiration from this book. It has a lot to teach other than simply the surface of the history of the discoveries it
This occurs when special carrier proteins carry solutes dissolved in the water across the membrane by using active transport. When the concentration gradient can not allow travel from one side of the membrane to the other fast enough for the cell’s nutritional needs, then facilitated diffusion is used. The transport protein is specialized for the solute it is carrying, just as enzymes are specialized for their substrate. The transport protein can be
38. Elsevier. Shaw, Jessica, Tanya Basok, Jeffrey Noonan, Suzan Ilcan, Nicol A. Noel. 2013. The.
When a cell membrane is said to be selectively permeable, it means that the cell membrane controls what substances pass in and out through the membrane. This characteristic of cell membranes plays a great role in passive transport. Passive transport is the movement of substances across the cell membrane without any input of energy by the cell. The energy for passive transport comes entirely from kinetic energy that the molecules have. The simplest type of passive transport is diffusion, which is the movement of molecules from an area of high concentration to an area of lower concentration. Diffusion
On a cellular level, Mrs. Jones’ cells are dehydrated due to osmotic pressure changes related to her high blood glucose. Cells dehydrate when poor cellular diffusion of glucose causes increased concentrations of glucose outside of the cell and lesser concentrations inside of the cell. Diffusion refers to the movement of particles from one gradient to another. In simple diffusion there is a stabilization of unequal of particles on either side of a permeable membrane through which the particles move freely to equalize the particles on both sides. The more complex facilitated diffusion is a passive transport of large particles from a high concentration of particles to a lower concentration of particles with the aid of a transport protein (Porth, 2011). The cellular membranes in our bodies are semipermeable allowing for smaller molecules to flow freely from the intracellular to extracellular space. The glucose molecule, however; is too large to diffuse through the cellul...
Scientists are still not entirely certain what all of the functions of a Merkel cell are, but it is agreed that they act as sensory touch receptors and respond to signals associated with mechanical stimuli. The process that transmits mechanical signals is slowly adapting, and research shows that Merkel cells are necessary in order for transduction to be successful when such a stimulus is sustained (Halata, Baumann, and Grim 4-9). In humans, Merkel cells perform their function through the secretory granules, which have short polypeptide compounds that act as neurotransmitters called neuropeptides (Moll et al. 251-271). Merkel cells release neurotransmitters in response to calcium ions enter the cell body. Some experts refer to these “touch cells” as neuroendocrine cells because they also produce and release certain hormones, although scientists can’t yet explain the purpose of this function (“What is a Merkel Cell?”). Maricich performed a study in which the transcription factor Atoh1 (expressed by Merkel cells) was deleted in mice, which resulted in a lack of neurophysiologic reactions for the subjects. Since the absent response is typically conducted by Merkel nerve endings, Maricich concluded that these “touch cells” are an essential part of the somatosensory system (Maricich et al.
This article relates to this course about Biology within the cells. This article relates to
In life, it is critical to understand what substances can permeate the cell membrane. This is important because the substances that are able to permeate the cell membrane can be necessary for the cell to function. Likewise, it is important to have a semi-permeable membrane in the cell due to the fact that it can help guard against harmful items that want to enter the cell. In addition, it is critical to understand how water moves through the cell through osmosis because if solute concentration is unregulated, net osmosis can occur outside or inside the cell, causing issues such as plasmolysis and cytolysis. The plasma membrane of a cell can be modeled various ways, but dialysis tubing is especially helpful to model what substances will diffuse or be transported out of a cell membrane. The experiment seeks to expose what substances would be permeable to the cell membrane through the use of dialysis tubing, starch, glucose, salt, and various solute indicators. However, before analyzing which of the solutes (starch, glucose, and salt) is likely to pass through the membrane, it is critical to understand how the dialysis tubing compares to the cell membrane.
The Importance of Diffusion to Living Organisms Diffusion is basically the movement of chemical species (ions or molecules) under the influence of concentration difference. The species will move from the high concentration area to the low concentration area till the concentration is consistent in the whole system. Diffusion mostly occurs in gases and liquids as these can move freely. The main features of an efficient diffusion system would be that it has a large surface area, thin membrane and a continuous supply of substances. A large surface area is needed so that high amount of substances can be exchanged at a time while the thin membrane means that the diffusion pathway would be short so that it is more efficient.
The cell plasma membrane, a bilayer structure composed mainly of phospholipids, is characterized by its fluidity. Membrane fluidity, as well as being affected by lipid and protein composition and temperature (Purdy et al. 2005), is regulated by its cholesterol concentration (Harby 2001, McLaurin 2002). Cholesterol is a special type of lipid, known as a steroid, formed by a polar OH headgroup and a single hydrocarbon tail (Wikipedia 2005, Diwan 2005). Like its fellow membrane lipids, cholesterol arranges itself in the same direction; its polar head is lined up with the polar headgroups of the phospholipid molecules (Spurger 2002). The stiffening and decreasing permeability of the bilayer that results from including cholesterol occurs due to its placement; the short, rigid molecules fit neatly into the gaps between phospholipids left due to the bends in their hydrocarbon tails (Alberts et al. 2004). Increased fluidity of the bilayer is a result of these bends or kinks affecting how closely the phospholipids can pack together (Alberts et al. 2004). Consequently, adding cholesterol molecules into the gaps between them disrupts the close packing of the phospholipids, resulting in the decreased membrane fluidity (Yehuda et al. 2002).
8. Becker W. M, Hardin J, Kleinsmith L.J an Bertoni G (2010) Becker’s World of the Cell, 8th edition, San Francisco, Pearson Education Inc- Accessed 23/11/2013.
Segal, E. A., Cimino, A. N., Gerdes, K. E., Harmon, J. K., & Wagaman, M. (2013). A