Using Spectroscopy to Evaluate the Absorption of Light for Different Substances

Using Spectroscopy to Evaluate the Absorption of Light for Different Substances Erin Laura and Polina, Section 13 BIOL 130, Monday 7:00-9:50pm Rm B2 151 Performed on October 20th, 2008 Introduction The purpose of experiment one was to determine the concentration of the unknown solution by using spectroscopy and comparing that substance to substances of known concentrations. In experiment two, the purpose was to discover the regions of the visible light spectrum are absorbed by both samples of chlorophyll. The spectrophotometer was an exceptionally useful tool for this lab. Spectroscopy is valuable for identifying substances through absorption of light which is done by measuring substances and comparing them to other known substances. Specifically a spectrophotometer is a device that measures the absorption of radiation at a particular wavelength. This is done by a light bulb shining, refracting its light into one beam, which then passes through an exit slit, then through the test solution and to a detector. This detects the amount of light that passed through the substance and a readout shows the amount of light that was absorbed (Jones, A, et al, 2007). Beer's Law states that concentration of a substance is directly proportional to its amount of light absorption (Department of Biology, 2008). The number of molecules of the solute is related exponentially to the amount

  • Word count: 1876
  • Level: University Degree
  • Subject: Biological Sciences
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Investigation to determine the water potential of potato cells.

Investigation to determine the water potential of potato cells. Planning Aim Carry out an experiment to determine the water potential of potato cells. Variables Independent Variable The variable that will be changed in this experiment is concentration of sucrose solution. I am using this variable because preliminary results show that this method is the best to use to determine the water potential of the cell contents. Dependent Variable The variable that will be measured is the mass change of the potato chips I can use these results to determine the average mass change per gram of the potatoes and I can then find out what the isotonic solution is for the potato chips, the concentration for the isotonic solution for the potato chips is the molarity of the potato cell contents and using this I can find out the water potential of potato cells. Control Variables There are many factors which control osmosis and the water potential of the cell contents these must be kept constant to ensure the experiment is a fair test. When the temperature increases, the rate of osmosis increases because the water particles have more energy and can move faster, so they will leave or enter the potato cells more quickly. At cold temperatures the water molecules will have less energy so less molecules will able to diffuse in the allotted time. If the temperature fluctuates significantly the

  • Word count: 2999
  • Level: University Degree
  • Subject: Biological Sciences
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How does Notch signalling mediate lateral inhibition? How is this mechanism thought to regulate timing in neurogenesis

Institute of Psychiatry MSc Neuroscience 2007 - 2008 FULL TIME STUDENT ESSAY Module 1: Essay Question No: 10 TITLE How does Notch signalling mediate lateral inhibition? How is this mechanism thought to regulate timing in neurogenesis? WORD COUNT: 2996 CANDIDATE NUMBER: K22563 PAGE NUMBER:15 How does Notch signalling mediate lateral inhibition? How is this mechanism thought to regulate timing in neurogenesis? In my essay I will be focusing on how Notch signals in the nervous system and how the ligand Delta mediates Notch signalling. In addition, I will also be explaining how various genes also play a role in lateral inhibition via Notch signalling. Furthermore I will explain how this mechanism regulates neurogenesis. Specification of cells at distinct times and places plays an important role for the production of cellular diversity in the vertebrate nervous system. Molecular signals that influence the generation of distinct cell types are spatially and temporally controlled. So therefore the neural pattern formation needs coordination of signals that provide temporal and spatial coordination. Lateral inhibition is one mechanism by which patterns of different cell types are produced and is a type of intercellular interaction by which a cell adopting the primary fate can inhibit its immediate neighbours from doing the same and therefore they adopt the secondary

  • Word count: 3852
  • Level: University Degree
  • Subject: Biological Sciences
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Virtual Investigation of an Enzyme. A new protease (ref. no PR/66-430-010), isolated from B.yorkii has been characterised. A series of experiments were run on the enzyme to determine the optimum pH for the enzyme to run at, the effect of pH on KM and Vmax

Summary I. A new protease (ref. no PR/66-430-010), isolated from B.yorkii has been characterised. II. A series of experiments were run on the enzyme to determine the optimum pH for the enzyme to run at, the effect of pH on KM and Vmax, to determine the effect of azide on substrate binding, on the catalytic process itself or both and also to determine the dissociation constant for the enzyme-azide complex and the accuracy of the measurements. III. Experiments performed on the isolated enzyme showed that if the pH of the solution was too high then the rate of reaction is too slow to gain any results and the same was true if the ph is too low. IV. The optimum pH was found to be pH 7.0 Results Fig.1 shows that the optimum pH at which the enzyme works at was pH 7.0. Fig.2 is a Lineweaver-Burk plot of the reciprocal values of the enzyme recorded at ph 7.0, with all values constant other than the concentration of the substrate. The Vmax and Km of the enzyme under inhibitor influence, double inhibitor and a control of no inhibitor were calculated from the lines of best fit on the plot and are as follows. Control Vmax - 1/0.35 = 2.9 Km - 1/15 = 0.06 Inhibitor Vmax - 1/0.35 = 2.9 Km - 1/4 = 0.25 Double Inhibitor Vmax - 1/0.35 = 2.9 Km - 1/2.5 = 0.4 Discussion The precision of the assay procedure was determined using the following data:

  • Word count: 589
  • Level: University Degree
  • Subject: Biological Sciences
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POMC cell function

The Prohormone 'Proopiomelanocortin' (POMC) is involved in several important cell functions. Critically review this statement in terms of its involvement in human pigmentation. A dissertation presented by Rekha Balakrishnan For the BSc (Hons) in Biomedical Sciences In the University of Bradford Division of Biomedical Sciences School of Life Sciences University of Bradford Bradford DATE of SUBMISSION 3rd April 2009 WORD COUNT 4788 TABLE OF CONTENTS Abstract 3 Introduction 4 Cell Functions of POMC 8 POMC Derived Peptides 12 The Importance of POMC- derived Peptide............................................... 15 POMC and Pigmentation 17 POMC and Pathology 20 Conclusion 22 Bibliography 25 Abstract This work reviews several important cellular-based functions of proopiomelanocortin (POMC), with emphasis on human skin pigmentation. As melanocortin peptides, PMOC regulates several physiological functions, including skin pigmentation, adrenal and cardiovascular functions, inflammation, energy homeostasis, and exocrine secretion. It also produces an array of biologically active peptides, by means of an extensive, tissue-specific posttranslational process. The skin is a target organ for the actions of POMC and its derived neuropeptides, including ?-melanocyte stimulating hormone (?-MCH), ß-endorphin, and ACTH. This study also surveys diseases associated with

  • Word count: 6944
  • Level: University Degree
  • Subject: Biological Sciences
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Investigating six different cell types. (spermatozoa smear, squamous epithelium cells, pollen grain, diatoms mixed, bacillus subtilis, & human blood)

In everyday life, we never think about the amount of cells that we shield or produce; least the structure, size or shape. Often in forensic investigation, scientists come across different types of cells, especially human cell (like spermatozoa cell, while investigating an alleged rape) or human fluid (like bacteria, which could be found in the blood and use for DNA profiling.) These cells can help investigators to know more about a case for example, pollen and diatoms could help a scientist to decide the geographical area of an incident. If it is underwater, Diatoms would be found or land (pollen). It can help to decide the type of environment an incident occurred. Cells can also help to explain if an evidence or body has been transported from one place to the other, i.e. it helps to locate the original crime scene. For example, if a body was found in the bush, after experimentation, scientist might found out that the body has been transported from one place to another, if there is diatoms in the body, it might identify the movement of corpse. According to Clegg (2000) Cell is the fundamental unit of life. This means that cells are the smallest part of any living thing; they serve as the basic building blocks of life that make up the structural and functional unit of all living organism. 'They contain the hereditary information, which is necessary for regulating cell

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  • Level: University Degree
  • Subject: Biological Sciences
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IMMUNOLOGY PRACTICAL: Differential Blood Cell Counts

IMMUNOLOGY PRACTICAL: Differential Blood Cell Counts AIM: To examine a prepared blood smears from humans in order to identify and count different types of white blood cell. Also to analyse and view the data, taken during the course of a parasitic infection (on mice). INTRODUCTION The total number of white blood cell does not necessarily indicate the severity of a disease, since some serious ailment may show a low white blood cell count. For this reason, a differential white blood cell count is performed. A differential white blood cell count consists of an examination of blood to determine the presence and the number of different types of white blood cells. This study often provides helpful information in determining the severity and extent of an infection, more than any other single procedure used in the examination of the blood. The role of white blood cells, or leukocytes, is to control various disease conditions. Although these cells do most of their work outside the circulatory system, they use the blood for transportation to sites of infection. There are five different types of white blood cells, which are normally found in the circulating blood. They are 1) lymphocytes, 2) neutrophils, 3) monocytes, 4) basophils and 5) eosinophils. Lymphocytes constitute 20-40% of the body's white blood cell and 99% of the cells in the lymph. These lymphocytes continually

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  • Level: University Degree
  • Subject: Biological Sciences
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Death and Disease From Dining

Problem/Solution Paper Trenton Albrecht Death and Disease From Dining Contrary to what most people think, problems with American food are a large cause of disease and death in the United States. Most people underestimate the strength of diseases such as E. Coli that are spread through food and affect many Americans every year from the lack of a genuine solution to prevent it. Although many problems can be found with the safety of food in America today, especially regarding cattle, much can be done to improve the situation. General food safety problems affect many people. In fact, eighty million Americans will get sick because of what they eat per year. Of those eighty million, 325,000 will be hospitalized, and 9,500 will die. One of the common diseases found in American food is salmonella, which occurs in poultry. Four million Americans will get sick from it, and five hundred will die from it each year. In addition to salmonella, Escherichia coli O157:H7, also known as E. Coli, is a bad disease that is found in meat, comes from cow feces and can infect people with only a few organisms. More outbreaks have been traced to ground beef with E. Coli than with any other food. To illustrate, an estimated twenty thousand Americans will get sick from it, and five hundred will die from it each year. Also, five percent of cattle have E. Coli, and ten percent of

  • Word count: 1210
  • Level: University Degree
  • Subject: Biological Sciences
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Medico-legal Problems of establishing the Time of Death

Medico-legal Problems of establishing the Time of Death No problem in forensic medicine has been investigated as thoroughly as that of determining the time of death on the basis of post mortem findings. Determining the time of death is of utmost importance but it is extremely difficult and accuracy is impossible. A recurring problem in forensic medicine is the need to fix the time of death within the limits of probability, the longer the interval of time between death and the examination of the body, the wider will be the limits of probability. The longer the post mortem interval, the more likely it is that associated or environmental evidence will furnish more reliable data on which to estimate the time of death than will anatomical changes. The post mortem interval (the time elapsed from death until discovery and medical examination of the body) may be preceded by a significant survival period (the time from injury or onset of the terminal illness to death). The survival interval is best established by evaluating the types, severity and number of injuries present and the deceased's response to them, taking into account pre-existing natural disease. At autopsy it is necessary to assess the evolution of the inflammatory response and repair process in skin and viscera. Three Sources of Evidence for estimating the time of death: . Corporal evidence; that present in the

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  • Level: University Degree
  • Subject: Biological Sciences
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The structure and function of membranes, with reference to membrane constituents and different types of membrane.

The structure and function of membranes, with reference to membrane constituents and different types of membrane. Membranes are essential for the compartmentalisation of a cell and therefore it is clear that the cell would struggle to develop any complexity without them. Although there are many different uses for membranes, especially in the eukaryotic cell, they serve a very important energetic purpose. For instance, they can retain a concentration gradient of, for example, Hydrogen ion, which means that the cell can use membranes not only for compartmentalising reactions, but also for compartmentalisation of energy and preventing diffusion. Therefore, without a complex system of membranes, the eukaryotic cell simply would not be able to carry out as many functions as it does. The prokaryotic cell differs in the sense that it does not possess membrane-bound organelles but still has an outer cell membrane. This has meant that it cannot carry out as many functions as the eukaryotic cells but its simplicity means that reproduction is far simpler. Therefore it is the membranes of the eukaryotic cell which are of more interest The basic constituents of all membranes are phospholipids, although there are different types of lipid present that I shall discuss later. All these molecules are amphipathic and therefore they have a polar 'head' and a hydrophobic 'tail'. They are based

  • Word count: 2107
  • Level: University Degree
  • Subject: Biological Sciences
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