LITERATURE REVIEW THE BIODEGRADABILITY OF STARCH-BASED PLASTICS
LITERATURE REVIEW - THE BIODEGRADABILITY OF STARCH-BASED PLASTICS Introduction The biodegradability, or rather, the non-biodegradability of conventional petroleum-based plastics is a pressing environmental issue. Approximately ten million tons of plastic products are discarded each year (Halley et al. 2001). Reusing and recycling plastics have been the first steps in combating the amount of municipal waste that is produced every day. However, mountains of synthetic waste are still generated at a dangerous rate despite efforts to reuse and recycle. A piece of petroleum-based plastic takes approximately 200 years to decompose naturally. As the demand for plastic products continues to rise, so does the pressure of finding a more environmentally-friendly alternative to conventional petroleum-based plastics. The search for an alternative has led researchers to develop biodegradable plastic blends from organic matter such as corn or potato starch. However, progress in the development of starch-based degradable plastics is slow and there is doubt as to whether degradable plastics are truly feasible. Degradable plastics are usually not as durable as petroleum-based plastics, also, and the breakdown products may be toxic to the environment. The development of these new plastics is further hindered by the potential economic strain of trying to manufacture these products to meet
Distinguishing Species of Bacteria
Distinguishing Species of Bacteria Introduction The purpose of this experiment is to distinguish species of bacteria by cultivating in different media and doing some tests. Another purpose of this lab is to learn the proper techniques of testing for fermentation of carbohydrates, production of indole, activity of urease, production of hydrogen sulfide, evidence of amylase activity, evidence of lipase activity, and evidence of protease activity. Different species of bacteria can be distinguished on the basis of the carbohydrates they do or do not utilize, as well as the nature of the products formed in the fermentation reaction. (Madigan and Thomas, 2009) Bacteria are able to ferment or breakdown simple carbohydrates to produce acidic, alcoholic, or gaseous end products. (Goldman 2009) By testing which bacteria species will ferment which carbohydrate and what products are formed allows one to identify. (Madigan and Thomas, 2009) The medium for the test is a nutrient broth with the acid-base indicator bromocresol purple. The test tube contains a Durham tube to collect gas that will be released in the medium when the carbohydrate is fermented. (Goldman 2009) Some organisms will not ferment at all, some will produce acid products and no gas, and some will make both acid products and gas. (Davidson, 2010) After inoculation, the tubes are incubated at 37ºC which is the optimal
“Additional Polymerisation, monomers join together without the loss of atoms from the molecule.”
"Additional Polymerisation, monomers join together without the loss of atoms from the molecule." (Reference 1) Additional polymerisation is the process in which many monomers bond together to produce large chains called 'Polymers'. Polyethene is an example of this. It is made of many ethene monomers linked together as one, commonly known as polythene. In additional polymerisation, all the monomers are alkenes (contain a carbon-carbon double bond). It is respectively this double bond that breaks and splits to form bonds with other ethene molecules. (Reference 3) There are certain conditions that need to be met for the reaction to be carried out efficiently. These are: Temperature: About 200°C Pressure: About 2000 atmospheres Initiator: A small amount of oxygen as an impurity This process starts with a new radical being donated, (a species with an unpaired electron.) In this case, it is donated from the oxygen, it is created by breaking the oxygen-oxygen bond, in such a way that the two electrons involved end up on the separated pieces of the original molecule, this is known as a 'homolytic cleavage'. E.g. Here is an example of a common inhibitor: Benzoyl Peroxide (Reference 4 ) The radical now combines with the spilt carbon-carbon double bond. The new radical continues to react with more alkenes and hence the chain grows. Eventually two free radicals
Antibiotic Resistance
Assignment 3: Evolution and Heredity Darwin's evolutionary hypothesis dictates the survival of the fittest. Accordingly, bacteria that overcome the onslaught of antibiotics (which can destroy them) and still replicate, provide a survival advantage for future generations of the same bacteria. However, from the human viewpoint, this genetic resistance to antibiotic treatment can be detrimental. Not only can ineffectiveness of antibiotics lead to exacerbation of an infection within an individual that may have been overcome, but can lead to the spread of an infection within a population that could have been contained. There is an economic consequence of this resistance as additional treatments, hospitalisation and lost labour hours cost money. More importantly, in the worst cases, unchecked infections of this type can lead to death. A very real example of this situation is multi-antibiotic resistance present in a strain of Staphylococcus aureus. This multi-resistance arose in stages1; penicillin resistant S. Aureus were first described within a few years of penicillin being introduced in clinical practice. To combat this resistance, a semi-synthetic penicillin, methicillin, was used. Within a year however, a penicillin and methicillin resistant Staphylococcus aureus (MRSA) strain was described. Subsequently, vanomycin has been used in the fight against MRSA but recently
Bacterial Resistance to Antibiotics.
Brad Godette Bacterial Resistance to Antibiotics November 15, 2002 In our world of "quick fixes", the rash use of antibiotics by doctors and their patients has resulted in a widespread problem of bacterial resistance to these drugs. Since penicillin was discovered, over 1,000 antibiotics have been invented (Novitt-Moreno 6). The extended over-use and mistreatment of these drugs has led to rampant resistance. Speaking from a strictly evolutionary point of view, the bacteria were forced both to evolve and adapt to this new situation or become extinct. Evolution is winning the battle against technology with the advent of "superbugs" which have become resistant to numerous antibiotics. As outlined by Blazquez et al, antibiotics are selectors and promoters of antibiotic resistance in microorganisms (345). This property creates a vicious cycle that can only be solved by a radical change in our research and development process of developing new antibiotics. Probably the most well know example of antimicrobial resistance is the widespread resistance to penicillin. In a span of three years, from 1941 to 1944, the bacteria Staphylococcus aureus developed penicillinase (now called ?-lactamase), an enzyme that easily breaks down penicillin. In contrast to 1941, when virtually every strain of S. aureus was susceptible to penicillin, today over 95% of S. aureus strains are
COSHH Risk Assessment for a Laboratory
COSHH Risk Assessment for a Laboratory On a daily basis as individuals we encounter all forms of harms or things that are detrimental to our heath and well being, for example when crossing the street you are open to being injured by a passing car or even when your riding a bike you are open to falling down and hurting yourself. Some of the harms we face can be avoided more particular the ones that occur in work places and laboratories. COSHH which stands for Control of Substances Hazardous to Health is the law that was implemented in 2002, it requires employers to control substances which are hazardous to the health of employees as well as others that may come in contact with the work place. The ideology behind COSHH was to ensure that it was safe for employees to work around substances or in environments that did not particularly favour good health; and in situations where by hazardous substances where unavoidable, good practices and controls were implemented to minimize the effects of coming in contact with them. Statistics have shown that since the implementation of COSHH work related deaths have decreased over time. In the work year 2002/2003 the death toll was 2261 and in the work year for 2009/2010 this number has dropped to 152.2 The latter still being a high number, the Health and Safety Executive (HSE) have maintained its firm stance behind the use of a COSSH
Find out the effect of temperature on enzyme activity.
Title: Temperature on Enzyme activity. Date: 29 September 2004 Aim: To find out the effect of temperature on enzyme activity. Theory: Like all enzymes, amylase catalyses a (bio) chemical reaction. A fundamental of chemical thermodynamics is that all reaction rates will increase as the temperature increases. With a typical amylase, therefore as you increase the temperature to the optimum, the rate at which an enzyme catalyses the breakdown of starch increases. Effect of temperature on reaction rate Increasing temperature will increase the rate of chemical reactions generally (kinetic energy of reactants is raised which increases the chances of favorable collisions). Enzyme catalyzed reactions will also increase with temperature due to the same reasons. However, catalytic activity depends on the enzyme having the correct conformation (molecular shape). As temperature increases the conformation of the enzyme is disrupted due to the increased kinetic energy of the enzyme molecule itself. Materials: . test tube rack 2. teat pipette 3. starch solution 4. 3 glass beakers 5. thermometer 6. 7 test-tubes 7. iodine solution 8. ice 9. clock 0. marker 11. amylase solution Procedure: . Seven test-tubes were labeled, 1,2,3,4,5,6, and 7 2. 3 cm of starch solution was placed in to each of test-tube 1, 2 and 3. 3. 4 drops of iodine solution was added to each of these
Microbes in Soil - Helping a Carbon Source or Sink?
Er Chian Kong (41004159) Essay - News and Views Environmental Microbiology & Bioresources BIOL 377 ______________________________________________________________________________ Microbes in Soil - Helping a Carbon Source or Sink? Soils hold a lot of carbon - 2000 gigatonnes in soil organic matter. This review looks at the relationship of the soil microorganisms and the aboveground plants in elevated CO2 and how they influence soil to be a carbon source or sink in a time where the concentration of CO2 in the atmosphere is constantly on the rise. Carbon is the key element of life and the carbon cycle binds together earth's ecosystems and their inhabitants. Carbon, in the form of carbon dioxide (CO2), is the major greenhouse gas released to the atmosphere. This ever increasing release of greenhouse gases cause global warming and raise the sea levels. The concentration of CO2 in the atmosphere has already increased by about 30% since the start of the industrial revolution in the 19th century and will continue to increase even as some countries had begun to use green renewable energy. Billions of years of intimate interaction of biotic and abiotic processes had give rise to complex and highly dynamic systems in soils. Approximately 50% of "typical" mineral topsoil comprises a mix of water and air-filled spaces that fluctuate according to prevailing environmental conditions
An antigen is anything which having invaded a host, causes the host to generate an immune response against itself. In this case the virus causing smallpox in humans and cowpox in cows.
An antigen is anything which having invaded a host, causes the host to generate an immune response against itself. In this case the virus causing smallpox in humans and cowpox in cows. Antigen receptors are cell-surface receptors of small lymphocytes that bind parts of the antigen. Antigen specificity is the ability of the host cells to recognise an antigen specifically as a unique molecular entity and distinguish it from another with exquisite precision. The ability to mount a response directed specifically against the unique epitopes that characterize a certain pathogen. Primary adaptive response is the response seen when a host meets a pathogen for the first time. It is slow to develop (7-10 days), takes 2-3 weeks to reach its peak and only lasts a few weeks. Secondary adaptive response is the enhanced response seen on subsequent infection with the same pathogen. It develops sooner, lasts longer and displays greater levels of activity. Epitopes are clusters of molecules on the surface of a pathogen, or in the structures of their harmful products (toxins), which are recognised as non-self. It is these biochemical clusters which trigger the immune response. Immunological memory is the term used to describe how the adaptive immune system appears to remember all pathogens it has encountered previously, and changes behaviour as a consequence of earlier experience. It
Determine the amount of gas evolved by the fermentation of different sugars by yeast.
Title: Specificity of enzymes: sugars metabolized by yeast Date: 6 October, 2004 Aim: To determine the amount of gas evolved by the fermentation of different sugars by yeast. Theory: In the absence of oxygen cellular respiration stops with glycolysis. The Krebs cycle and electron transport chain do not function. Pyruvate accumulates in the cytoplasm and oxidized form of NADH (NAD+) is depleted. When all of the NAD+ is gone, glycolysis stops and the cell dies. To avoid death, cells possess alternate pathways to regenerate NAD+ and keep glycolysis functioning in the absence of oxygen. This process is called anaerobic respiration or fermentation. In anaerobes, glycolysis and fermentation are the only respiratory pathways present. In plants and some fungi, fermentation converts pyruvate (3 carbons) to ethanol (2 carbons) and CO2. Synthesis of the ethanol provides an electron (and hydrogen) acceptor that regenerates NAD+ from NADH and allows glycolysis to continue. Yeast belongs to the group of organisms called fungi. The fungi cannot produce their own food, but given the right kind of food, yeast cells can perform the reactions of fermentation, producing carbon dioxide (a gas) and ethanol. The rates of the chemical reactions of fermentation depend on the action of enzymes. The enzymes present in yeast cells are specific and will only catalyse the fermentation of