To determine the water potential of a potato tuber cell using varying salt solution.
Aim To determine the water potential of a potato tuber cell using varying salt solution. Introduction Osmosis is the diffusion of water molecules from a region where it has higher water potential to a region where it has lower water potential through a partially permeable membrane1. As osmosis is a type of diffusion the same things that affect diffusion have an effect on osmosis some of theses things are: * The concentration gradient - the more the difference in molecules on one side of the membrane compared to the other, the greater the number of molecules passing through the membrane and therefore the faster the rate of diffusion2. * The surface area - the larger the area the quicker the rate of diffusion * The size of the diffusing particles - the smaller the particle the quicker the rate and polar molecules diffuse faster than non-polar ones3. * The temperature - the higher the temperature the more kinetic energy the particles have and so the faster they move. From the diagram4 we can see the process of osmosis in a simple expression. On the right side there is pure water, which has the maximum water potential of 0. Water potential is the pressure created by water. As you can see from the diagram the pure water is pushing its way through the semi permeable membrane at a high pressure. This is its water potential. Water potential is measured in kilopascals (kPa)
effects of substrate concentration on the activity of the enzyme catalase.
Investigate the effects of substrate concentration on the activity of the enzyme catalase. To explain this, catalase is an enzyme found in potato cells, catalase breaks down the substrate Hydrogen-Peroxide into water + oxygen. Hydrogen Peroxide itself is a waste product found in potatoes and other fruit + vegetables. When I do this I will see with different concentrations of the substrate and see how quick the enzyme catalase works on it. The four things that affect the rate at which the substrate and enzyme would react are as follow:- * Susceptibility of temperature change. * Susceptibility to PH changes. * Enzyme concentration. * Substrate concentration. Now I will explain each one of these in detail and how they can change the rate of reaction in many different ways. Susceptibility of temperature: - Chemical reactions can be speeded up by heating the reactants, this makes molecules speed up and have sufficient energy for more successful collisions. If the temperature is too high the enzyme would vibrate and it would denature because the active-site would change shape. Susceptibility of PH changes: - Enzymes can be denatured by changes in PH. This happens because the ionisation of the Amino acids changes, the Ionic bonds with stabilise the enzyme, that shape is broken so they are no longer stable. So you need the right PH for the ionic bonds to stay stable for the
How the structure of cells is related to their function.
How the structure of cells is related to their function. All living things are made up of cells, whether its plants, humans or even bacteria. There are two different types of cells one is the prokaryotic and the other is the eukaryotic. The name cell was used by an English man who in 1665 use the first microscope and reported seeing what he described looked like the sleeping chambers in the monasteries that were called cells, in a piece of cork.1 The first of the two types is the Prokaryotic cell, the pro meaning before the nucleus as this cell has no true nucleus.2 Prokaryotic cells are surrounded by a cell wall and a cells membrane, and in some ways this makes them similar to a plant cell which is eukaryotic, but they have no nucleus or organelles inside, but they do have flagella's and cilia on the outside. The flagellum is a long whip like tail attached to the end of the prokaryotic cell which helps with its movement. The cilia are small spiked hairs that help to transport fluid in and out of the cell and for protection against harmful substances. They are also found in abundance in the eukaryotic cells in the human trachea where they collect dirt, they either by moving it down into the stomach or push it back up into to the mouth to spit it out.3 One of the most common prokaryotic cells would be bacteria, they are the smallest cellular organism, and each human being
Effects of Surface Area on Catalase Activity in Potato.
Effects of Surface Area on Catalase Activity in Potato Aim To investigate the effect of surface area on the activity of Catalase in potato. Hypothesis I predict that the potato which has been cut into more pieces will have the largest surface area. A larger surface area means that there will be more catalase molecules coming in contact with the reacting substrate, hydrogen peroxide. Enzymes react when particles come into contact with their active sites; if more of the enzyme is exposed (larger surface area) a greater number of active sites will be available to react with the hydrogen peroxide. The surface area of a 5cm tube with a diameter of 2cm equals 37.0 cms² ( 2 rh+2 r² ), but a 5 cm tube cut into five 1cm segments has a surface area of 62.83 cms². Every time another segment is cut from the 5cm tube two more areas have to taken into account, this means each time the 5cm tube is cut into a piece the surface area will increase. As a larger surface area produces a higher rate of reaction, my results should show a higher volume of gas released when using a potato with a larger surface area. Background Knowledge Enzymes are proteins which can be referred to as biological catalysts. Catalysts are molecules which increase the rate of chemical reactions and remain unchanged at the end of the reaction. Enzymes are made up of a chain of amino acids which are
The Effect of pH on Catalase
The Effect of pH on Catalase Hypothesis: The rate at which catalase catalyses the decomposition of hydrogen peroxide increases to an optimum pH and then decreases as the optimum pH is exceeded. Biological knowledge: Hydrogen peroxide is produced in plant and animal cells as a by-product, which is toxic, resulting in the need of catalase to speed up the decomposition of hydrogen peroxide to water and oxygen. All microbodies contain catalase and it is the fastest known enzyme with a turnover number of 6 million. It is especially abundant in plant storage organs and in liver. It is effective over the pH range of 4.0 to 9.0 with the optimum pH of 7.6. 2H2O2(aq) catalase 2H2O(l) + O2(g) As an enzyme, its rate is affected by various factors, including pH. Changes in pH alter the ionic charge of acidic and basic groups of the enzyme. This therefore distorts the shape of the enzyme, including its active site, where substrates temporarily bind. The efficiency of forming enzyme-substrate complexes is consequently lowered and the rate of activity decreases. However, the enzyme can regain its most proficient shape, if it is not exposed to too extreme pHs, to return to its maximum rate of activity when placed back at the optimum pH. Plan: The volume of oxygen produced during the catalysed break down of hydrogen peroxide can be measured in a graduated gas syringe
What factors affect osmosis?
What factors affect osmosis? In my investigation I am going to attempt to discover if osmosis is affected by a certain factor. Osmosis is the movement of water from an area of high water concentration through a semi-permeable membrane to an area of low water concentration. Osmosis is affected by water potential which is the term used to describe the movement of a concentration of water, and as a general rule water always falls from an area of high water concentration to an area of low water concentration in a similar way to gravitation or electrical potential. In simple terms, it is sometimes referred to as the diffusion of water. I am going to find out how the concentration of a solution affects osmosis in an investigation using potatoes and sucrose solution. Osmosis depends upon a semi-permeable membrane because this allows water to pass both ways through the membrane but not other solutions with larger molecules, for example sucrose solution (see diagram to the right). A number of factors could affect osmosis such as; type of plant material, temperature, type of solution or concentration of solution. I could have chosen to investigate any of these factors effect on osmosis but instead I chose to investigate the concentration of solution, as I believe it will have the greatest effect on osmosis and will allow me to show a higher level of scientific knowledge and I chose
Investigating the effects of surface area on the rate of enzyme reactions.
AS Biology Coursework assignment Investigating the effects of surface area on the rate of enzyme reactions By Scott Humm Introduction Enzymes basically are biological catalysts. What this means is they have the ability to speed up reactions without actually being used up themselves. Enzymes are globular proteins and they have a three-dimensional shape, which is very precise and never varies between two examples of the same protein. The active site for all molecules of the same enzyme will be made up of the same arrangement of amino acids. This exact shape and arrangement of amino acids enables the enzymes to be highly specific and this defines which substrate they bind to in the active site. Because they are so specific, enzymes are thought to catalyse substrate into two different products by the "Lock and Key hypothesis". Diagram taken from http://schools.moe.edu.sg/chijsjc/Biology/Enzyme/enzyme.htm This diagram shows how enzymes catalyse the breakdown of a substrate molecule into two products. The only way that another molecule can bind with an enzyme's active site is if it is an inhibitor. Inhibitors are molecules that can bind with the active site briefly causing competition between itself and any substrate molecules. When there is a very high concentration of inhibitors, substrate molecules do not bind with active sites as easily because there are less of them.
An Experiment to determine Water Potential in Potato Tissue.
An Experiment to determine Water Potential in Potato Tissue Introduction Osmosis is the movement of water molecules move from a region of high water concentration (high water potential) to a region of low water concentration (low water potential). The water molecules also move through a partially permeable membrane. Osmosis affects the shape of plant cells. When a plant cell is in a lower water potential (highly concentrated solution), water from the plant cell moves out and therefore it becomes flaccid, and this is when the cell membrane of the plant cell shrinks. When a plant cell is in a solution which has higher water potential, the water moves into the cell and therefore it becomes turgid, this is when the cell membrane expands. In both cases, it is only the cell membrane that changes its shape. The cell wall always keeps its shape. The mass of plant cells change as well. This is because water is moved into or out of the plant cell and therefore a change occurs to its mass. At equilibrium (when the solution's water potential and the plant cell's water potential are the same) there will be no movement of water. Therefore the shape and the mass of plant cell would stay the same. The tendency of water molecules to move from one place to another is measured as the water potential, which is represented by the sign ?. It is a Greek letter for Psi. The water molecules can
Genetic fingerprinting
25/11/09 Genetic Finger Printing ) Genetic fingerprinting is a method which identifies people using only samples of their DNA. It produces very precise results and is used a lot in forensic science and paternity testing. A small sample of hair, blood or other tissue is given. This sample will contain white blood cells which are broken open using detergent. Then enzymes cuts the DNA making it smaller and this is added to agarose gel. Finally the pieces of DNA receive either coloured or radioactive probes. The pattern is recorded and produces the DNA fingerprint. 2) Genetic fingerprinting Is used for : * Diagnosing Genetic disease - Mutations in the DNA can show inherited diseases and predicts tendency to some diseases. If particular diseases run in a family, it can help predict if individuals or their unborn children are at risk as well. * Forensic science - To match crime suspects to samples of skin, hair, blood or saliva found. * Paternity testing - The DNA from the mother, child and alleged father are compared. The DNA matching DNA between the mother and the child are ignored and the left over DNA from the father are observed and can determine who is the father. * Organ Donor - To match DNA samples between two people and ensure that they are compatible. * Study of animal - Scientists use the DNA to measure the amount of genetic variation between different species
The Economic Impact of the Use of Enzymes in Industry.
The Economic Impact of the Use of Enzymes in Industry Enzymes are very precise protein molecules with a high specificity which are used to catalyse chemical reactions by lowering the activation energy required for the reaction to take place. It is these properties of being able to break down substances easily and bind specifically to certain chemicals that make enzymes very useful in many industries and practices throughout the world. In addition to this enzymes are not used up in experiments so products of processes are not contaminated with enzyme which could be a problem. This essay explains 3 uses of enzymes, in industry and food, diagnosing and analysing, and treating disease, explaining the function and advantages of enzyme use in each example. An enzyme is a biological catalyst, used for speeding up chemical reactions in cells. They are all proteins; and work by making and breaking bonds. They are not used up during a reaction, and a good catalyst can accelerate a reaction by up to 10 times. When they do this, they reduce the activation energy needed for the reaction, which means that the rate of reaction is increased. For example, catalase increases the decomposition rate of hydrogen peroxide into water and oxygen. It lowers the activation energy of the reaction from 75 kJ per mol to 21 kJ per mol. One molecule of catalase can break 40 million
