...First I will describe the parts of the cell. The cell wall is a rigid box like structure found in plant cells. The cell wall protects the cell from unwanted particles , and stops the cell from bursting when too much water is present inside the cell. The cell membrane is responsible for five types of diffusion. The first diffusion is simple passive. Simple transport allows small particles to pass through the phospholipid bilateral from a high to low concentration. Examples of particles that can pass through the phospholipid bilayer are lipids, water, and other small particles. The second type of diffusion is active transport. Active transport goes from low to high concentration, therefore it uses ATP to allow particles through the cell membrane....
Words: 893 - Pages: 4
...2 ABSTRACT The effect of molecular weight on the rate of diffusion was assessed using two tests: the glass tube test and the agar-water gel test. In the glass tube set-up, two cotton plugs soaked in two different substances (HCl and NH4OH) were inserted into the two ends of the glass tube. The substance with the lighter molecular weight value (NH4OH, M = 35.0459 g/mole) diffused at a faster rate (dAve = 25.8cm), resulting in the formation of a white ring around the glass closer to the side of the heavier substance (HCl, M = 36.4611 g/mole; dAve = 10.8 cm). The agar-water gel set up was composed of a petri dish of agar-water gel containing three wells. Drops of potassium permanganate (KMnO4), potassium dichromate (K2Cr2O7) and methylene blue were simultaneously introduced to each well. Methylene blue, having the largest molecular weight, displayed the smallest diameter (18 mm) and diffused at the slowest rate (0.3668 mm/min.). Thus, the higher the molecular weight, the slower the rate of diffusion. INTRODUCTION A substance in the gaseous or liquid state consists of molecules or atoms that are independent, rapid, and random in motion. These molecules frequently collide with each other and with the sides of the container. In a period of time, this movement results in a uniform distribution of the molecules throughout the system. This process is called diffusion (Everett and Everett, n.d.). Diffusion occurs naturally, with the net movement of particles flowing from...
Words: 2656 - Pages: 11
...ABSTRACT The effect of molecular weight on the rate of diffusion was assessed using two tests: the glass tube test and the agar-water gel test. In the glass tube set-up, two cotton plugs soaked in two different substances (HCl and NH4OH) were inserted into the two ends of the glass tube. The substance with the lighter molecular weight value (NH4OH, M = 35.0459 g/mole) diffused at a faster rate (dAve = 25.8cm), resulting in the formation of a white ring around the glass closer to the side of the heavier substance (HCl, M = 36.4611 g/mole; dAve = 10.8 cm). The agar-water gel set up was composed of a petri dish of agar-water gel containing three wells. Drops of potassium permanganate (KMnO4), potassium dichromate (K2Cr2O7) and methylene blue were simultaneously introduced to each well. Methylene blue, having the largest molecular weight, displayed the smallest diameter (18 mm) and diffused at the slowest rate (0.3668 mm/min.). Thus, the higher the molecular weight, the slower the rate of diffusion. INTRODUCTION A substance in the gaseous or liquid state consists of molecules or atoms that are independent, rapid, and random in motion. These molecules frequently collide with each other and with the sides of the container. In a period of time, this movement results in a uniform distribution of the molecules throughout the system. This process is called diffusion (Everett and Everett, n.d.). Diffusion occurs naturally, with the net movement of particles flowing from an area...
Words: 331 - Pages: 2
...Econometrics ] (]]]]) ]]]–]]] www.elsevier.com/locate/jeconom Modeling the diffusion of scientific publications Dennis Fok, Philip Hans Fransesà Econometric Institute, Erasmus University Rotterdam, P.O. Box 1738, NL-3000 DR Rotterdam, The Netherlands Abstract This paper illustrates that salient features of a panel of time series of annual citations can be captured by a Bass type diffusion model. We put forward an extended version of this diffusion model, where we consider the relation between key characteristics of the diffusion process and features of the articles. More specifically, parameters measuring citations’ ceiling and the timing of peak citations are correlated with specific features of the articles like the number of pages and the number of authors. Our approach amounts to a multi-level non-linear regression for a panel of time series. We illustrate our model for citations to articles that were published in Econometrica and the Journal of Econometrics. Amongst other things, we find that more references lead to more citations and that for the Journal of Econometrics peak citations of more recent articles tend to occur later. r 2006 Elsevier B.V. All rights reserved. JEL classification: C33; M21 Keywords: Diffusion of innovations; Multi-level regression 1. Introduction Citations to scientific publications like journal articles often show characteristics that bear similarities with the diffusion of a new product. Shortly after publication, there are not many citations...
Words: 8068 - Pages: 33
...Atichai Suwannapeng Pre Lab #6 Diffusion, Osmosis, and Tonicity Group #3 Section A3 Group Members: Laghu Shakya, Alex Maican, Kelvin Chen, Ziye Lin 10/18/2015 Abstract: In this lab we will be gaining an understanding of how transport in membranes work. This is important because in our semi permeable cell membrane the mode of movement relies on transport. Some methods of transportation for molecules are simple diffusion, facilitated diffusion, active transport, exocytosis and osmosis. The reason molecules tend to move around when dissolved in a solution is because all molecules display random thermal motion and have kinetic energy. Kinetic energy is what allows the molecules to diffuse down a gradient of high concentration to regions of low concentration until the distribution of molecules become equal and achieved dynamic equilibrium. The entire solution only becomes homogeneous when one of the several factors are reached: the size of the dye molecules, temperature of the solution, density of the solvent and concentration of the dye. Heat is what causes random motion of molecules and passively moves molecules in biological systems. However, we can’t see this movement with our naked eye. In order for us to see this movement, we must use a microscope to see the small particles move after collision, this is called the Brownian movement. When talking about the cell membrane we must understand that it is selectively permeable, which means it can choose what can pass through...
Words: 1835 - Pages: 8
...www.elsevier.com/locate/comnet Molecular communication options for long range nanonetworks Lluís Parcerisa Giné *, Ian F. Akyildiz The Broadband Wireless Networking (BWN) Laboratory, School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, USA a r t i c l e i n f o a b s t r a c t Nanotechnology is an emerging field of science devoted to provide new opportunities in a vast range of areas. In this paper, different techniques are proposed to enable the long range interconnection of nano-machines, deployed over distances from a few centimeters up to several meters. Long range nano-communications will enable the development of applications that could not be implemented using other techniques. The usage of both short-range nano techniques and long range micro techniques are not practical or are unfeasible for a huge application scope. Biologically inspired research provides promising features to long range communication, such as very low power consumption and biocompatibility. In this paper, several bio-inspired techniques are discussed following a twofold taxonomy divided according to whether a fixed physical link is required for signal propagation or not, i.e., either wired or wireless communication. In the first group, pheromones, spores, pollen and light transduction are discussed. In the second group, neuron-based communication techniques and capillaries flow circuit are explored. All proposed techniques offer a good framework for...
Words: 11420 - Pages: 46
...Diffusion and Osmosis Diffusion is the passive movement of molecules or particles along a concentration gradient, or from regions of higher to regions of lower concentration. Osmosis is a type of diffusion. This is the diffusion of water through a selectively permeable membrane (chooses what comes in and what goes out) from a region of higher water potential to a region of lower water potential. Water potential is the measure of free energy of water in a solution. Unlike diffusion, osmosis requires ATP to move the particles across the membrane. Hypothesis: In both experiments diffusion and osmosis will occur between the solutions. In experiment 1A the tube of glucose/starch will absorb the iodine solution in the cup. In experiment 1B the tube of distilled water will lose weight, and the tube of glucose will gain weight. The purpose of the experiments is to differentiate which test was diffusion and which was osmosis. Materials: Experiment 1A: Plastic Cup, Plastic Pipet, Iodine-Potassium Iodide, Deionized Water, Glucose Paper Strip Experiment 1B: (3) 15 cm pieces of Dialysis Tubing, beaker, 15 cm piece of white thread, 80% Glucose, 2% Starch, Plastic cup, 10% glucose, 15 cm blue thread, distilled water, 15 cm red thread, 20% glucose Procedure Experiment 1A: First cut a 15-cm length of dialysis tubing. Place the dialysis tubing in a beaker of distilled water and allow it to remain in the beaker for 1 minute. Open the dialysis tube by rolling it in between thumb...
Words: 1249 - Pages: 5
...Introduction Osmosis is a key for every living organism on Earth, from humans to plants. In this lab we examined the processes of osmosis and diffusion. Osmosis is a specialized type of diffusion; “it is the process of water moving across a semi-permeable membrane, in response to a concentration gradient” (Readel, 2000). Fluid passes both in and out of the semi permeable membrane in osmosis, but usually there is a “net flow in one direction or another, depending on which side of the membrane has a higher concentration of solutes” (Smith, 2013). There are different factors that can affect the rate of osmosis such as temperature. In one experiment, my group and I used dialysis tubing to simulate a cell membrane. This tubing was filled with molasses and was immersed in water; cold, warm and hot. The bags were removed at regular intervals and measured for the amount of osmosis that occurred. We observed that the bags in the hot water experienced the highest amount of osmosis. In warmer temperatures the water particles tend to diffuse from high to low concentration, thus trying to dilute the solute concentration from the solution outside. From these observations and conclusion, my group and I hypothesized for our own experiment the level of solute concentration will affect the rate of osmosis. Diffusion is the process of “any substance moving from a region of high concentration to a region of lower concentration” (Readel, 2000). Therefore we predicted that the higher concentration...
Words: 1054 - Pages: 5
...The purpose of this experiment was to demonstrate how diffusion and osmosis moves across a dialysis membrane. The sub-purpose was to determine if the sucrose solution, that was in dialysis tubing would leak into the distilled water. The hypothesis states that if a sucrose solution, in dialysis tubing, is placed into a beaker filled with distilled water the net movement of sucrose will be into or out of the dialysis bag. The null hypothesis states that if the sucrose solution in a dialysis bags mass may change after taking it out of the water each time to be weighted between each 15-minute increment 5 different times. After 15, 30, 45 and 60 minutes it can be concluded that weighing the sucrose solution in the dialysis bag increased in weight after each increment. Keywords: Diffusion, Osmosis, Dialysis bag, Sucrose solution, Distilled water Introduction...
Words: 1136 - Pages: 5
...Solute Concentration of Potatoes Carmen Chen Blk: 7 December 14, 2013 Purpose: to determine the concentration of solute in potatoes cytoplasm. Materials and Equipment: refer to the lab sheet. Observations: | |Concentration of sucrose|Initial mass |Final mass |Percentage change in | |Test tube # |solution ( |(g) |(g) |mass | | |mol/L) | | |(%) | |1 |1.0 |3.0 |-0.9 |-30% | |2 |0.9 |3.9 |-1.2 |-30.8 % | |3 |0.8 |3.2 |-0.7 |-21.9% | |4 |0.7 |3.5 |-0.8 |-22.9% | |5 |0.6 |3.3 |-0.6 |-18.2% | |6 |0.5 |3.0 |-0.3 |-1% | |7 |0.4 |3.1 |-0.2 ...
Words: 1426 - Pages: 6
...lighter molecular weight value diffused at a faster rate. Thus, resulting in the formation of a white smoke in the glass tube moving closer to the side of the heavier substance Hydrochloric Acid (HCl). The agar-water gel set-up consisted of a agar-water gel in a petri dish. Potassium Permanganate (KmnO4), Methylene Blue (C16H18N3SCl) had a drop in each well. Methylene Blue, having the heaviest weight, diffused slowly. Therefore, the heavier the molecular weight, the slower the rate of diffusion. Introduction Many interesting biological facts but usually, when modifications or experiments are tried, the investigator has some reason for doing so. A substance in the gaseous or liquid state consists of molecules or atoms that are independent, rapid, and random in motion. These molecules frequently collide with each other and with the sides of the container. In a period of time, this movement results in a uniform distribution of the molecules throughout the system. This process is called diffusion. Diffusion is a process of equalization which involves movement of molecules from an area of high concentration to an area of low concentration. Materials and Methods Results Methylene Blue(MW: 320g/mole) | Potassium Permanganate(MW : 158g/mole) | Time(min) | Distance (mm) | Rate(mm/min) | Time(min) | Distance (mm) | Rate (mm/min) | 0 | 15 | 0 | 0 | 24 | 0 | 15 | 16 | 1.06 | 15 | 32.67 | 2.178 | 30 | 16.3 | 0.5 | 30 | 36.67 | 1.23 | 45 | 17 | 0.38 | 45 | 40.3 | 0.89 | 60...
Words: 297 - Pages: 2
...oxygen produced as a byproduct remains dissolved in water. The basic reaction of aquatic photosynthesis remains: CO2 + H2O → (CH2O) + O2 As aquatic photosynthesis is dependent on light, the dissolved oxygen manufactured will be the highest in the course of daylight hours and decline at night (Stiff et al., 1992). Gill morphology The gills are carried right after the head of the fish, neighboring the posterior boundaries of a sequence of openings from the esophagus to the outside. Each gill is supported by a cartilaginous or bony gill arch. The vertebrate gills characteristically progress in the pharyngeal walls, along a sequence of gill slits that open to the external. Most species employ countercurrent exchange system to enhance the diffusion of substances in and out of the gill, with water and blood flowing in conflicting directions to each other. There are usually four gills on each side consisting of a curved bony gill-bar bearing many thin and narrow filaments. Blood vessels tracks through the gill-bar which directs divisions into the gill filaments. The filaments carry reduced filaments down their extent which, in turn, separate into smaller branches. So an excessive number of miniature branches provide a very large surface area when the gills are immersed in water. The walls of the gill filaments, called the gill lamellae are very shrill, allowing the oxygen to diffuse quickly into the blood by increasing the surface area for oxygen exchange. A convenient way of visualizing...
Words: 1745 - Pages: 7
...Fatmata Diffusion Abstract dialysis tubing is, made of cellulose because it’s a selectively permeable membrane. In this experiment, we are testing to see if the solution in the beaker moves into the dialysis bag. Which because of that, Introduction Diffusion and osmosis are two types of transport mechanisms. Diffusion is the movement of molecules from areas of higher concentrations to areas of lower concentration until the molecules are evenly distributed through the area. Osmosis is the dispersion of water. Our cells are capable of absorbing nutrients because, the cell membrane is selectively permeable (some molecules can diffuse freely through the membrane while others cannot). In this experiment we used dialysis bag as a model of the cell membrane. Our hypothesis was that the glucose will diffuse out of the membrane into the beaker filled with iodine solution. To demonstrate dialysis tubing we used water, starch and iodine. When starch and iodine react together they form a dark brown color. Materials Rubber band | Dialysis bag | Beaker | Glucose solution | Iodine solution | Water, thread | Methods * Cut a piece of dialysis tubing that has been soaking in water approximately 40 cm (approx. 16 in) long, Tie the end of the dialysis tubing with two or more knots. * Fill the bag halfway with glucose solution. And add 4 full droppers of starch solution to the bag. * Hold the open end close while you mix the content o the bag. Rinse of outside the bag...
Words: 535 - Pages: 3
...to elucidate the transmitter types involved. The results suggest a different hypothesis that the JAR is controlled by two separate motor pathways. One controlling rise in frequency originates in the dorsal substructure of the nucleus electrosensorius. It sends excitatory connections to the PPn-G and finally to the pacemaker nucleus, where AMPA-type receptors mediate the synaptic transmission. The second pathway controlling fall in the frequency originates in the ventral substructure of the nucleus electrosensorius. It provides GABAergic input to the SPPn, which is tonically active controlling the EOD frequency even in the absence of jamming signals. Its projection to the pacemaker nucleus is mediated by NMDA-type receptors. Concluding the paper, Metzner suggested that there is no single population of final, feature-extracting elements or “recognition units” that controls JAR-related shifts of the pacemaker frequency holding the idea that the motor control of the JAR consists of an interaction of two independent pathways according to a “push-pull” principle. Fortune et al in 2006 further delved into the phenomena of JAR to identify and characterize circuits involved in the behavior. Due recent progress in the study of electrosensory systems, Fortune re-analyzed this circuit, in relation to newly described electrosensory behaviors, that include prey capture, social signaling and the tracking of electrosensory objects which lead to a re-evaluation of the broader functional relevance...
Words: 688 - Pages: 3
...materials to enter or leave the cell. This is a vital function of the cell membrane. Using the Physio Ex CD 9.0, you will be able to conduct experiments showing the important cell membrane processes of diffusion, osmosis, filtration, and active transport. The simulations will allow you to alter conditions to show the effect of concentrations, pore size, pressure, carrier, and ATP have on movements of materials through the cell membrane. Purpose: To conduct experiments showing the effects of concentration, ions, and particle size of movement through the cell membrane. Materials: Lab manual, PhysioEx 9.0 Procedure: Cell Transport Mechanisms and Permeability in the lab manual. You will also need the PhysioEx 9.0 CD for this lab. Read over exercise overview and introduction. Complete the following questions from the exercise as you complete the simulation exercises. Go to Exercise 1 Cell Transport Mechanisms and Permeability on the CD. Follow the directions and complete each part. Answer questions or fill in tables as you proceed through the experiment. Place your answers in the spaces provided below. Submit your lab in Moodle. Activity 1. Simple Diffusion Chart 1 |Chart 1 Dialysis Results(average diffusion rate in mM/min | | |...
Words: 1920 - Pages: 8
