Nervous System
Nervous System Coursework The Nervous System is the most complex and delicate of all the body systems. At the centre of the nervous system is the brain. The brain sends and receives messages through a network of nerves. This network can be explained as similar to a road network. The spinal cord is a thick bundle of nerves which runs down the centre of the spine. This is like a freeway. Along the spinal cord smaller bunches of nerves branch out. These are like highways From these bundles, smaller bundles of nerves branch out again. These are like main roads. Finally, individual nerves branch out to every part of the body. These are like normal roads. This network of nerves allows the brain to communicate with every part of the body. Nerves transmit information as electrical impulses from one area of the body to another. Some nerves carry information to the brain. This allows us to see, hear, smell, taste and touch. Other nerves carry information from the brain to the muscles to control our body's movement. Many drugs, such as alcohol and cigarettes, affect the way that our nerves work. This can result in us not being able to control our body, as well as we should. How Nerve Cells Communicate Each microscopic nerve cell, or neuron, has a blob shaped main part, the cell body, with thin, spider-like dendrites and one much longer, wire-like nerve fibre or axon. The
Nervous system
The Importance of the Human Nervous System Human's ability to survive in often stressful and varying environments directly reflects their ability to maintain a stable internal environment. Human homeostasis refers to the body's ability to physiologically regulate its inner environment to ensure its stability in response to fluctuations in the outside environment. The nervous system (NS) and the endocrine system share responsibility for maintaining homeostasis, their objective is to communicate, control and co-ordinate body activities. The NS regulates this by instantaneous, short-lived and localised response based on electrical impulses as apposed to the endocrine system which responds slowly with long-term processes such as growth and maturation by releasing hormones. (4) Besides maintaining homeostasis, the NS is also responsible for the seat of language, emotion and memory along with voluntary and involuntary movements making it one of the most complex and important systems in the human body. (4) (1) Topographically the NS can be divided into two main subdivisions, the central nervous system (CNS) and the peripheral nervous system (PNS). (4) The CNS is a massive collection of nerve cells called tracts which are connected in an intricate fashion to sub-serve the higher order functions such as control of movement or the analysis of sensation via integrating and
Nitrogen Cycle
Nitrogen Cycle Most nitrogen is found in the atmosphere. The nitrogen cycle is the process by which atmospheric nitrogen is converted to ammonia or nitrates. Nitrogen is essential to all living systems. To become a part of an organism, nitrogen must first be fixed or combined with oxygen or hydrogen. Nitrogen is removed from the atmosphere by lightening and nitrogen fixing bacteria. During electrical storms, large amounts of nitrogen are oxidized and united with water to produce an acid which is carried to the earth in rain producing nitrates. Nitrates are taken up by plants and are converted to proteins. Then the nitrogen passes through the food chain from plants to herbivores to carnivores. When plants and animals eventually die, the nitrogen compounds are broken down giving ammonia (ammonification). Some of the ammonia is taken up by the plants; some is dissolved in water or held in the soil where bacteria convert it to nitrates (nitrification). Nitrates may be stored in humus or leached from the soil and carried to lakes and streams. It may also be converted to free nitrogen (denitrification) and returned to the atmosphere. The nitrogen cycle is one of the most difficult of the cycles to learn, simply because there are so many important forms of nitrogen, and because organisms are responsible for each of the introversions. Remember that nitrogen is critically
Enzyme Investigation.
Enzyme Investigation. Aim: To look at how enzyme concentration affects the rate of the reaction. I am going to be investigating how by changing the concentration of enzyme the reaction speed alters. This is part of our work on the function of enzymes, how they work and the effects of conditions on how they work. We have learnt about the formation of enzyme-substrate complexes, the lock and key model, induced fit model, activation energies of normal reactions and enzyme-catalysed reactions, equilibrium, specificity and denaturation. Firstly I would like to talk about the enzyme, catalase and the substrate, hydrogen peroxide. In organisms, hydrogen peroxide is a toxic by-product of metabolism of certain cell oxidations to be more specific. Hydrogen peroxide on its own is relatively stable and each molecule can stay in this state for a few years. Its decomposition therefore needs to be speeded up greatly in order to prevent it from intoxicating the cell. This is where catalase comes in. Catalase has to be very fast acting to keep the hydrogen peroxide levels low, and it is one of the fastest acting enzymes known to man. It catalyses the decomposition of hydrogen peroxide, liberating oxygen gas as bubbles, each molecule of the globular protein decomposing 40,000 molecules of hydrogen peroxide per second at zero degrees Celsius (figures taken from Biology Review online)
Enzyme Investigation.
Enzyme Investigation Enzymes such as Catalase are protein molecules, which are found in living cells. They are used to speed up specific reactions within the cell. They are all very specific as each enzyme just performs one particular reaction. Catalase is an enzyme found in food such as potato and liver. It is used to remove Hydrogen Peroxide from cells. Catalase speeds up the decomposition of Hydrogen Peroxide into water and oxygen because the shape of its active site matches the shape of the Hydrogen peroxide molecule. This type of reaction where a molecule is broken down into smaller pieces is called a catabolic reaction. This is the reaction equation for the breakdown of hydrogen peroxide into water and oxygen: Hydrogen Peroxide + Catalase = Water + Oxygen. 2H202 2H20 + 02 Aim: The aim of this experiment was to examine the effect of catalase on the breakdown of the substrate hydrogen peroxide. The catalase used was obtained from a piece of liver. An enzyme is a biological catalyst. Catalysts speed up reactions. Most enzymes optimum working temperature is 37 (body temperature), however the optimum working temperature of catalase is 30 . Enzymes have their optimum temperature which is when the molecules of the enzyme are moving at their fastest. This makes it more likely that the enzyme molecules will collide with substrate and react more
ENZYME INVESTIGATION
ENZYME INVESTIGATION Planning Introduction: An Enzyme is any one of many specialised organic substances, composed of polymers of amino acids, that act as catalysts to regulate the speed of the many chemical reactions involved in the metabolism of living organisms. Those enzymes identified now number more than 700. Enzymes are classified into several broad categories, such as hydrolytic, oxidising, and reducing, depending on the type of reaction they control. Hydrolytic enzymes accelerate reactions in which a substance is broken down into simpler compounds through reaction with water molecules. Oxidising enzymes, known as oxidises, accelerate oxidation reactions; reducing enzymes speed up reduction reactions, in which oxygen is removed. Many other enzymes catalyse other types of reactions. Individual enzymes are named by adding ASE to the name of the substrate with which they react. The enzyme that controls urea decomposition is called urease; those that control protein hydrolyses are known as proteinases. Some enzymes, such as the proteinases trypsin and pepsin, retain the names used before this nomenclature was adopted. Structure and Function of an Enzyme Enzymes are large proteins that speed up chemical reactions. In their globular structure, one or more polypeptide chains twist and fold, bringing together a small number of amino acids to form the active site,
Enzyme Investigation.
Alex Boultwood 11a Mr. Francis Enzyme Investigation. An enzyme is a protein molecule composed of polymers of amino acids that speeds up chemical reactions in all living things. Without enzymes, these reactions would occur too slowly or not at all, and no life would be possible. All living cells produce enzymes. Enzyme molecules function by altering other molecules. They dramatically increase the rate at which reactions occur within living organisms, without being 'used up' or effecting the reaction in any other way. Enzymes combine with the altered molecules to form a complex molecular structure in which chemical reactions take place. The enzyme, which remains unchanged, then separates from the product of the reaction. Therefore, enzymes are called biological catalysts. Enzymes save the need for an increase in temperature in order to speed up reactions within living things. Such an increase in temperature would be lethal to the organism. Hydrogen Peroxide is a waste product in the liver. Catalase is an enzyme that catalyses the breakdown of Hydrogen Peroxide. Catalase work extremely quickly with the ability to convert six million Hydrogen Peroxide Molecules into water and oxygen in a minute. How Enzymes Work. Enzymes work faster as the temperature increases but only to a certain point. This is because as you heat a reaction up, the particles move faster. This
Enzyme Investigation.
Enzyme Investigation PLAN Protease enzymes are produced in three different areas of the alimentary canal. These three areas are the mouth, stomach and small intestine. The enzyme in the mouth is the saliva produced in the mouth. It acts on chewed pieces of food, beginning the process of digestion. The food leaves the mouth when swallowed and begins to travel down the oesophagus. Muscles in the walls of the oesophagus contract rhythmically to move food from the throat to the stomach. This contraction is the process called peristalsis. When food reaches the stomach physical digestion occurs where there are continual churning movements of the muscular walls. These churning movements reduce food to a creamy paste called chime. Chemical digestion occurs by enzymes and acids being released by the cells of gastric glands. Pepsinogen is firstly released into the stomach. Hydrochloric acid converts the pepsinogen into the enzyme which catalyses the hydrolysis of proteins into polypeptides. The chime is then released a little at a time into the duodenum, which is the first few centimetres of the small intestine. The gall bladder produces bile containing protease enzymes, which is released into the small intestine. The enzymes breakdown large food molecules into simple and more soluble molecules. The bile released, contains sodium hydrogen carbonate which helps to
Enzyme investigation
Charlotte Mortlock Enzyme investigation Dec 01 In this investigation we are trying to find out how variables affect the rate of oxygen and water produced in hydrogen peroxide. The enzyme that we are working with is called, catalyse. This can be found in living things, for example- it is found in the human liver. As we know there are all sorts of enzymes, all uniquely designed to break down, different substances. Our enzyme, catalyse, is designed for the breaking down of a toxic substance, known as Hydrogen Peroxide, into water and oxygen. The chemical equation for this is- 2H2O2 ? 2H2O+O2. Catalyse is also present in yeast. We will be using yeast that has been immobilised into beads. We will be looking at the possible variables, and deciding on our chosen one. The variable will help us to investigate what affects the speed of reaction. The possible variables are- * Temperature * Size of beads * Concentration * Ph Our chosen variable is the first one, temperature. In order to produce the appropriate amount of results for this investigation, we will be filling five test tubes with hydrogen peroxide, obviously each tube will be at a different temperature, and adding the yeast beads to the solution. Due to the presence of oxygen the beads will rise. We will comment on how our chosen variable affects the rate of the reaction. To find out how
Enzymes are catalysts. Most are proteins.
Enzymes are catalysts. Most are proteins. (A few ribonucleoprotein enzymes have been discovered and, for some of these, the catalytic activity is in the RNA part rather than the protein part. Link to discussion of these ribozymes.) Enzymes bind temporarily to one or more of the reactants of the reaction they catalyze. In doing so, they lower the amount of activation energy needed and thus speed up the reaction. Most of these interactions are weak and especially so if the atoms involved are farther than about one angstrom from each other. So successful binding of enzyme and substrate requires that the two molecules be able to approach each other closely over a fairly broad surface. Thus the analogy that a substrate molecule binds its enzyme like a key in a lock. This requirement for complementarity in the configuration of substrate and enzyme explains the remarkable specificity of most enzymes. Generally, a given enzyme is able to catalyze only a single chemical reaction or, at most, a few reactions involving substrates sharing the same general structure. Competitive inhibition The necessity for a close, if brief, fit between enzyme and substrate explains the phenomenon of competitive inhibition. One of the enzymes needed for the release of energy within the cell is succinic dehydrogenase. Link to illustrated discussion of the citric acid cycle. It catalyzes the
