The Cytoskeleton - Its Functions and Structure
The Cytoskeleton-Its Functions and Structure I have decided to base my essay on the cytoskeleton as this is a very interesting field of biology and there are copious amounts of information and research involving it. I hope by doing this essay I can extend my knowledge of the cytoskeleton and that it may help me during my forthcoming exams. The first thing that must be understood about the cytoskeleton is that it is not present in all living cells. The cytoskeleton is unique to eukaryotic cells and is not present in prokaryotes such as bacteria. It is suggested that the cytoskeleton may have been a crucial factor in the evolution of eukaryotic cells. The cytoskeleton is like a scaffold, made up of fibrous proteins in the cytoplasm of a cell. It's a very dynamic three-dimensional. Cells can easily adopt a variety of shapes and carry out coordinated and directed movements because they possess this network of fibrous proteins. Some of the functions that the cytoskeleton serves that will be discussed more further on in the essay include: establishing cell shape, providing mechanical strength, locomotion, chromosome separation in mitosis/meiosis and intracellular transport of organelles. These diverse activities of the cytoskeleton depend on different types of protein fibres which are, actin filaments (or otherwise known as microfilaments), microtubules and intermediate
Components of Biological Membranes.
Components of Biological Membranes Introduction. Biological membranes surround all living cells, and may also be found surrounding many of an eukaryotes organelles. The membrane is essential to the survival of a cell due to its diverse range of functions. There are general functions common to all membranes such as control of permeability, and then there are specialised functions that depend upon the cell type, such as conveyance of an action potential in neurones. However, despite the diversity of function, the structure of membranes is remarkably similar. All membranes are composed of lipid, protein and carbohydrate, but it is the ratio of these components that varies. For example the protein component may be as high as 80% in Erythrocytes, and as low as 18% in myelinated neurones. Alternately, the lipid component may be as high as 80% in myelinated neurones, and as low as 15% in skeletal muscle fibres. The initial model for membrane structure was proposed by Danielli and Davson in the late 1930s. They suggested that the plasma membrane consisted of a lipid bilayer coated on both sides by protein. In 1960, Michael Robertson proposed the Unit Membrane Hypothesis which suggests that all biological membranes -regardless of location- have a similar basic structure. This has been confirmed by research techniques. In the 1970s, Singer and Nicholson announced a modified version
Molecular Properties of Enzymes
The Molecular Properties of Enzymes Sean Tavakoli March 8, 2010 Section: A020 Abstract: In this experiment, the effects of boiling and inhibitors on enzyme activity were studied. Methods used to carry out this study were the use of an indicator substance, methylene blue, and qualitative measurements of the changes in color that occur. Structurally similar substances were used as substrates and inhibitors in order to allow competitive inhibition to occur. A pH buffer was used in order to keep the pH constant for each sample observed. All of the test tubes were exposed to the same temperature so that all enzymes have the same rate of reaction, however for another set of experiments I changed the temperatures around to determine if heat had an effect on enzyme efficiency. The variables in this experiment were whether the enzyme was fresh or boiled and the presences of substrate and inhibitor. I hypothesized that the presence of an inhibitor hinders an enzymes ability to react with substrate. Also, that after boiling, an enzyme is unable to catalyze a reaction (Frankel 2009 et al pg 32 and 53) Introduction One of the most essential inferences to existence is credited to the rate and efficiency of chemical reactions that occur within an individual cell. In order for many of these reactions to be successful, they need a unique type of globular protein recognized as an enzyme.
DETERMINATION OF THE VALENCY OF THE MAGNESIUM
NAME: THAMARAI A/P RAJENDRAN ID NUMBER: 09ALB07214 LABORATORY 1A: ATOMIC STRUCTURE, BONDING AND PERIODICITY COURSE: BIOTECHNOLOGY (YEAR 1 SEM 1) EXPERIMENT 6: DETERMINATION OF THE VALENCY OF MAGNESIUM TITLE: Determination of the Valency of Magnesium OBJECTIVES OF EXPERIMENT: This experiment is to study the quantitative relations between amounts of reactants and products of a reaction. A known starting mass of magnesium and the measured collection of hydrogen gas will be used to determine the reaction stoichiometry. THEORY AND BACKGROUND: Stoichiometry is the study of the quantitative relations between amounts of reactants and products of a reaction (that is how many moles of a reactant A react with a given number of moles of B). in this section, a known starting mass of magnesium and the measured collection of hydrogen gas will be used to determine the reaction stoichiometry. The term stoichiometry is also often used for the molar proportions of elements in stoichiometric compounds. For example, the stoichiometry of hydrogen and oxygen in H2O is 2:1. In stoichiometric compounds, the molar proportions are whole numbers (that is what the law of definite proportions is about). Stoichiometry is not only used to balance chemical equations but also used in conversions, i.e., converting from grams to moles, or from grams to milliliters. Reaction stoichiometry allows
Complement Practical
COMPLEMENT PRACTICAL The term "complement" was applied by Ehrlich to describe the activity in serum, which could "complement" the ability to specific antibody to cause lysis of bacteria (Immunology, Roitt et al, 4th ed). The complement system plays a crucial role in host defence against infectious agents and in the inflammatory process. It consists of twenty plasma proteins that function either as enzymes or as binding proteins that act as a cascade, where each enzyme acts as a catalyst for the next, with C3 being the most important component. The complement system also includes multiple distinct cell-surface receptors that exhibit specificity for the physiological fragments of complement proteins and that occur on inflammatory cells and cells of the immune system. The consequences of complement activation are: > Opsonisation > Activation of leucocytes > Inflammation > Lysis of target cells There are three different mechanisms that the complement system uses for recognising micro-organisms. The first pathway to be discovered was the classical pathway. It is activated by the binding of antibody molecules, specifically IgM and IgG1, 2 and 3 to a foreign particle i.e. antigens. Here, the complement proteins work together with antibodies to enhance the removal of antigen-antibody complexes from the body. Another common pathway is the alternative pathway. This
Compare and Contrast Vertebrate and Invertebrate Vision
Compare and Contrast Vertebrate and Invertebrate Vision Although vertebrates and invertebrates originally evolved from a common ancestral root, both have developed very different physical utilities for vision. Both are fairly effective and have taken many millions of years to evolve. They contain many common underlying mechanisms but differ in the features used to provide them. The definition of an eye is 'an organ of visual perception that includes parts specialized for optical processing of light as well as well as photoreceptive neurons' (Alberts). The main feature of an eye therefore, in all organisms that possess one, is the collection of photoreceptors used in converting light energy into action potentials (electrical energy). When comparing vertebrate and invertebrate vision, the two best-studied cases are the compound eye exemplified by arthropods and the simple eye used in vertebrates. The main difference between the compound and simple eye is that the compound eye uses a spatial array of lenses so that each image in a local region of visual space falls onto one or a few photoreceptors. The simple eye, however, uses a single lens to image the world onto an array of photoreceptors. Compound eyes produce mosaic images. The compound eye is made up of many optical units called ommatidiums, each of which is aimed at a different part of the visual field. Each
Effect of temperature on membrane permeability
Effect of temperature on membrane permeability Aim This investigation aims to determine what effect an increase in the surrounding temperature has on the plasma membrane of a typical plant cell structure. Hypothesis An increase in temperature will damage and denature the plasma membrane, which would cause the substances contained within the cytoplasm to leak out of the membrane. The investigation carried out was to see the "effect of temperature on membrane permeability". Different temperatures were used, ranging from room temperature to 87°C. Three test tubes were used to give a range of results. They were placed in a colorimeter, from which a percentage was recorded showing how much light had passed through. Figure 1 shows the results obtained from the investigation. A mean has also been calculated and included in the results. Temperature (°C) Test tube 1 (%) Test tube 2 (%) Test tube 3 (%) Mean (%) 23 98 96 96 96.67 45 95 93 91 93.00 53 74 73 73 73.33 65 54 45 34 44.33 87 Figure 1: A table showing the results obtained. From the above results it can be seen that as the temperature increases, the permeability of beetroot membrane increases. This shows that the plasma membrane must be denatured. In the cells of a beetroot plant, a substance called anthocyanin is contained within the plasma membrane. It is anthocyanin which gives the beetroot
Proteins. The experiment aimed to extract proteins from green papaya through salting out with the use of ammonium sulfate. Ultrafiltration was then done in preparation to ion-exchange chromatography which would be employed to purify the crude protein extr
PROTEINS I. Objectives: The experiment aimed to extract proteins from green papaya through salting out with the use of ammonium sulfate. Ultrafiltration was then done in preparation to ion-exchange chromatography which would be employed to purify the crude protein extract. Amersham Hi-Trap Sephadex Desalting Column would be utilized to further purify the samples. SDS-PAGE was then be employed to isolate and further analyze and purify the proteins in the sample. Finally, silver stain was utilized to visualizeand keep track of the purity of the proteins. II. Introduction: Proteins are complex organic macromolecules that are built from the 20 common building blocks called amino acids arranged in a linear chain linked together by peptide bonds between the carboxyl and the amino groups of adjacent amino acid residues. Usually, proteins contain 200-300 amino acids although some are made up of thousands of amino acids like titin, the largest known protein found in skeletal and cardiac muscles containing 34350 amino acids. Proteins are vital to every organism as it participates in virtually every process within cells like metabolism, cell cycle, immune responses, cell signaling, cell locomotion, transport of materials in body fluids and a lot more. In this experiment, green papaya was utilized as the source of protein. Green papaya is the unripe fruit of the plant Carica papaya
STOICHIOMETRY REACTION
NAME : THAMARAI A/P RAJENDRAN ID NUMBER: 09ALB07214 LABORATORY 1A : ATOMIC STRUCTURE BONDING AND PERIODICITY COURSE: BIOTECHNOLOGY (Y 1 S 1) EXPERIMENT 3: STOICHIOMETRY REACTION TITLE: Stoichiometry Reaction. OBJECTIVES OF EXPERIMENT: The objective of this experiment is to decompose sodium hydrogen carbonate(sodium bicarbonate) by heating, and to accurately measure the degree of completion of the reaction by analyzing the solid sodium carbonate product. THEORY AND BACKGROUND: We need to know how much product we will get from a given amount of reactant and we also need to know how much heat a given reaction produces in order to be able to safely perform the reaction. When we measure chemical or physical quantities of starting materials or products, these are a function of the molecular transformations involved in the reaction. That is, the reaction stoichiometry (whether a molecule of compound X reacts with 1 or 2 molecules of Y) must be involved in any calculation about amounts of reactants or products. However, in the laboratory, we must be concerned with far larger quantities than the molecular scale. Similarly, going in the reverse direction, we must be able to relate the amount of heat evolved in a laboratory scale reaction to that involved when two molecules react. The scaling factor used to relate readily usable quantities to the molecular scale is called
Why are conservationists concerned about gene flow?
Why are conservationists concerned about gene flow? This essay intends to look at how the process of gene flow can be of concern to conservationists, by examining some specific examples that emphasise the problems that often result from it. The essay will begin with a brief description of what gene flow is, before explaining why it can be a problem. It will then go on to discuss an example of naturally occurring gene flow - in blue tits among Southern France; followed by an example of gene flow resulting from human activities - that of the use of Genetically Modified Organisms; that result in concerns from conservationists. The essay will then use the example of a pocket gopher species to show how diverse a species can become when gene flow is absent. The essay will conclude by suggesting possible ways of reducing the negative effects of gene flow and explaining why, despite there being possible situations where gene flow could have positive influences, as a whole it can only ever be seen as a negative process from the conservation perspective. Gene flow is one of the four generally accepted processes that lead to evolution, along with mutation, genetic drift and natural selection. While the latter two act to change the frequencies of alleles that already exist in a population; gene flow, along with mutation, can actually act to bring new alleles into a population. Gene