Ion transport thorough nanoscale pores is a common process in various biological phenomena. Ion channels, in particular, play an important role in physiological functions such as the generation of electrical activity in nerves and muscle, volume regulation of cells, intracellular signaling and so on. Malfunctioning channels have been linked to wide range of diseases. For instance, abnormal sodium channels in membranes of muscle cell cause Hyperkalemic Periodic Paralysis and abnormal potassium channels results in heart arrhythmia. It is also known that malfunctioning chlorine channels are the root cause of cystic fibrosis. Several other disorders are caused by faulty ion channels like epilepsy, diabetes, ataxia and hypertension [bagal, Shieh, Choi]. Discovery of drugs to restore the proper behavior of malfunctioning ion channels is a challenging problem because of the wide variety of channel types as well as their complex behavior. The purpose of our study is to connect the mechanism of ion transport in biological channels to features at the molecular level, and give a quantitative understanding of the processes responsible for ion channel function. This is widely recognized as an area in need of development. Ultimately, it will allow for the design of new drugs and treatments that restore mutated channels to their proper functioning.
Ion transport also has novel applications in medical technology. It has been demonstrated that measuring the ionic blockade signal of different nucleotides translocating through a pore may form the basis of a rapid DNA sequencing technique [colloquium, clarke]. This technique doesn't require expensive sample preparation and enzyme-dependent amplification, and thus will drastically reduce the time an...
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...f solid state nanopores show that when ions pass through the pore their hydration layers are distorted. When the pore diameter is very small, the hydration layer has to be stripped off as the ion passes through the pore. The energetic cost associated with the partial removal of the hydration layer causes step-like features in the ionic conductance as a function of pore radius [dehydration, Josi]. We want to examine this process in graphene nanopores. Dehydration of ions in these pore is interesting for multiple reasons: 1) the dynamics of the process, in addition to energetics, is expected to play a large role because of the small size and 2) these pores will allow for the systematic investigation of the factors contributing to complex biological ion channel. Moreover these pores can be fabricated much more precisely and result in more well-controlled experiments.
In the cells of the late distal tubule and the cortical collecting tubule, the basolateral membrane contains the sodium/potassium ATPase pump and a potassium channel. The apical membrane contains both sodium and potassium channels.[5]
The ratio of transport number of anion a and chloride ion, PaCl is defined by eq.(1) [7].
Our first goal in Project 7 was to determine what our three unknown solutions were. We did this through a series of tests. Our first test was a series of anion tests. We performed anion tests to determine whether any of the following anions were present in our solution: chloride, sulfate, nitrate, carbonate, and acetate. Our first solution, labeled as B, had only the chloride test come out positive. The next solution, C, tested positive for acetate, as did our last solution, E. We next performed anion tests. These included flame test, as well as an ammonium test. For the flame test, certain cations turn flames different colors, so we used this knowledge to test to see which cations could be present in our solutions. During this test, the only solution that appeared to turn the flame any color was solution C, which turned the flame bright orange, indicating the sodium ion was present. This led us to the conclusion that solution C was sodium acetate. We next performed an ammonium test, which involved mixing our solutions with sodium hydroxide, and smelling the resulting solution in order to detect an ammonia smell. Solution B was identified as smelling like ammonia, indicating the presence of the ammonium cation. From this, we identified solution B as ammonium chloride. We next checked the pH of all three of the solutions, first by using litmus paper. Solution C was slightly basic, solution E and B were both acidic, with a pH around 4. Since we knew that solution E had acetate, and was acidic, and did not turn the flame any color, we determined it was acetic acid, as none of the ions in acetic acid would turn a flame any color.
Primordial cells would have had a similar concept and function to this compartmentalization, though perhaps not utilizing the same components as current cells. Their membrane would have most likely consisted of amphiphilic molecules like fatty acids or possibly polyprenyl phosphates, similar to modern day archaea. However, having a pure lipid bilayer would result in inadequate exchange of charged ions and large polar molecule between the environment and the cell, especially without the use of transporter proteins. Propositions have been proposed that cell membranes and membrane proteins have co-evolved, in that, cell membranes have moved from porous to ion-tight, just as membrane proteins have moved from amphiphilic pore forming proteins to very hydrophobic integral membrane proteins. A proposed schematic of this membrane-protein co-development involving the increasing complexity of F and V-type ATPases and sodium ion transporters with membranes porous to both protons and sodium ions, becoming more ion-tight can be observed in figure 1-5 (Mulkidjanian et al.
Tsou, J. A., Hagen, J. A., Carpenter, C. L., & Laird-Offringa, I. A. (2002, August 05). DNA
In a laboratory scientist will use a process called gel electrophoresis to separate DNA fragments. The DNA is cut into different sized fragments as a result from using restriction enzymes. The different sized DNA fragments are organized injected on agarose gel with an added substance that helps it glow after the test. DNA is negatively charged. Electricity is producing a positively charged are and a negatively charged area. Opposites attract and as a result the negatively charged DNA will move quickly to the positively charged area. Smaller DNA fragments will run faster the larger DNA fragments. After the electricity is turned off smaller DNA fragments will be closer to the positively charged area and the larger DNA fragments will be farther from the positively charged area. While it is glowing scientist can take a picture of the data and record the results and compare DNA samples to look for any abnormalities.
Bangham AD, Standish MM, Watkins JC. Diffusion of univalent ions across the lamellae of swollen phospholipids. Journal of Molecular Biology. 1965 8//;13(1):238-IN27.
The procedure for this experiment can be found in Inorganic Chemistry Lab Manual prepared by Dr. Virgil Payne.
Activity 3: Investigating Osmosis and Diffusion Through Nonliving Membranes. In this activity, through the use of dialysis sacs and varying concentrations of solutions, the movement of water and solutes will be observed through a semipermeable membrane. The gradients at which the solutes NaCl and glucose diffuse is unproportional to any other molecule, therefore they will proceed down their own gradients. However, the same is not true for water, whose concentration gradient is affected by solute ...
Electrolyte can be defined as the aqueous or molten substances which when dissolved in a solvent dissociates into ions and can transmit negatively charged ions.
24. Ujjal Kumar Sur, “Graphene: A Rising Star on the Horizon of Materials Science,” International Journal of Electrochemistry, vol. 2012, Article ID 237689, 12 pages, 2012. doi:10.1155/2012/237689
The current moves the molecules towards the cathode or anode. The speed of the moving molecules depends on the size, shape, and charge. The properties of the gel will definitely affect the movement. Small molecules are expected to move easily and faster through the pores. Materials and Methods: Experiment: 1st step to make the gel: pour distilled water and agarose in a beaker.
Pauly, S. (2011, February). News from ABC: changes and challenges. Analytical & Bioanalytical Chemistry. pp. 1003-1004. doi:10.1007/s00216-010-4459-0.
Ions are critical to human health. As defined by Dictionary.com, an ion is an electrically charged atom or group of atoms formed by the loss or gain of one or more electrons. The human body is the most intricate of ‘designs,’ despite the fact it is composed of basic natural resources called elements. The ions discussed in this paper include oxygen, carbon, potassium, and sulfur. A healthy body is composed of these ions, along with others (zinc, fluoride, iron, etc.). The absence of these elements could lead to an unhealthy body, and make it an easier target for diseases. The chemical formulas, charges, and properties will also be discussed in this document. Also, addressed is the essential role of the ion presented, the way in which the ion serves the body, the diseases that may result from deficiency, and the global distribution of these deficiencies. Ions are an essential part of human health. The ions that are present make the body’s daily functions possible, allowing it to be protected from cruel bacteria or diseases.
Humans these days take electricity for granted. We don’t truly understand what life was like without it. Most young adults will tell you their life does not depend on electricity, but they aren’t fooling anyone. They all know that their life depends on electricity; whether it’s television, their phone, Google, or the lights in their house. We need to stop taking those things for granted and give credit where credit is due. That is why I chose to write about the scientists who contributed to the discovery of electricity, which then helped modern scientists fuel the electricity phenomenons we now have today.