The structure and function of carbohydrates.
The structure and function of carbohydrates Carbohydrates are named for their characteristic content of carbon, hydrogen, and oxygen (CH2O). Carbohydrate molecules are categorized by the number of carbons present in the molecule. Short chains containing from three to seven carbons form the monosaccharides, which are the most basic sugars. Monosaccharides with five or more carbons can form a ring as well as a linear configuration. The rings form through a reaction between two functional groups in the same molecule. Each carbon atom in the chain, except one, carries an -OH group. The remaining carbon carries a -C=O (carbonyl) group. In monosaccharides hydrogen atoms occupy all other available binding sites of carbon. Glucose, the most common monosaccharide has six carbons per molecule, which is called a hexose. Carbohydrates also have 2:1 hydrogen to oxygen ratio. This aids in the condensation and hydrolysis reactions. A condensation reaction occurs when two monosaccharides join by the removal of water (H2O). During condensation synthesis one monosaccharide losses an OH and the other losses an H. As a result the two monosaccharides bond by forming maltose a disaccharide with a by-product of a free H2O molecule. When three or more monosaccharides or monomer are involved in a condensation synthesis a polymer or polysaccharide is formed with a by-product of water. Starch and
The theory of endosymbiosis
The theory of endosymbiosis (Endo Within, Symbiosis Living together! ) I am going to analyze the theory of endosymbiosis over the next few pages. I am going to give arguments for and against so I can make a reliable conclusion. First of all I am going to give some information about the theory of endosymbiosis. According to the theory of endosymbiosis, billions of years ago mitochondria and chloroplasts were free-living bacteria (prokaryotes) which somehow became part of an early cell. The primitive Earth did not have oxygen in its atmosphere so these early cells must have been able to survive with out oxygen. However, oxygen gradually oxygen built up in the atmosphere and it is possible that some bacteria evolved which were able to use oxygen for respiration (aerobic bacteria). According to the theory, an aerobic bacterium became engulfed by an anarobic amoeba-like bacterium, and the amoeba-like bacterium navigated through the newly oxygen rich waters in search of food. In support of this theory of endosymbiosis, scientists have shown that oxygen began to accumulate between the first fossil records of prokaryotes and the later fossil records of eukaryotes. Anaerobic amoeba-like Anerobic bacterium Aerobic bacterium bacterium. engulfs aerobic bacterium. becomes symbiotic inside
What are 'Enzymes'?
Introduction Enzymes are biological catalysts that carry out thousands of chemical reactions that occur in living cells. They are a class of proteins that have a unique three dimensional structure that allows it to bind with a specific substrate to facilitate a reaction. Many biological reactions will not occur spontaneously in the cell; there is simply not enough energy for the reaction to take place. Enzymes make these reactions possible by lowering the reaction's activation energy. Each cell has tens of thousands of different enzymes that collectively allow both the break down and synthesis of molecules to drive all cellular processes. This investigation will explore the effect of pH on the three-dimensional structure of a protein. Much of the three-dimensional structure of an enzyme is held together by weak interactions including H-bonds, ionic bonds, and hydrophobic interactions. These interactions can be easily disrupted by changes in temperature, salt concentration, and pH. pH levels out of the normal intracellular range would denature enzymes, slowing the enzyme's reaction rates. Hydrogen peroxide (H2O2) is a toxic chemical that is continually being formed as By product of reactions in peroxisomes of living cells. Since it is poisonous, the cells must either get rid of it or change it to something nonpoisonous. If they cannot do this, the cell may die;
What are enzymes?
Enzymes What are enzymes? Enzymes are biological catalysts they alter the rate of reaction without it self being used up or changed during the reaction. Without enzymes the reactions that take place in an organism would be too slow for life to continue. Enzymes are proteins and how an enzyme functions is determined by its three dimensional structure. An enzyme has: > Three dimensional shape > Area on its surface called Active site The substance that the enzyme helps to react is called the substrate. Substrate has complementary to the active site and the substrate fits into the active site. The active site of each of each different enzyme has its own particular three-dimensional shape so only a substrate with a complementary shape will fit it. Most enzymes catalyse speed up only one reaction or one group of reactions. Below shows the break down Maltose to Glucose Maltase + Maltose = Maltase + Glucose In the above reaction Maltose is the substrate and Maltase is the enzyme and the product formed is Glucose. Maltase will only speed up the break down of Maltose to Glucose it does not act on ant other substrate. How they work? Like all other particles in the cell Enzyme molecules are constantly moving about colliding with other molecules. When an enzyme molecule collides with its substrate molecule the substrate binds to the enzymes active site. The substrate when
What are 'Enzymes'?
Enzymes Enzymes are proteins and are biological catalysts. They speed up chemical reactions that happen within living things. They are very efficient at doing their job. To give you an idea of efficiency one catalase molecule can break six million hydrogen peroxide molecules into harmless water and oxygen per minute. There are two types of enzymes extracellular enzymes and intracellular enzymes. Extracellular enzymes are made inside cells, once formed they may move out and do its job outside of the cell an example of extracellular enzymes is the enzymes in the digestive system. Intracellular enzymes are also produced inside the cell, however they work within the cell speeding up the chemical reactions they can also control reactions. An example of an enzyme-controlled reaction is: Maltase (enzyme) Maltose (substrate) Glucose (product) The substance that the enzyme acts on (Maltose) is called the substrate. The new substance(s) formed is called the product(s). This reaction, along with many metabolic reactions, is reversible meaning maltose can become glucose or glucose can become maltose. They way the reactions turns depends on the proportions of glucose to maltose. If there is a lot of maltose and little glucose then the reaction will be as above but if there is less maltose than glucose then it will go
What are 'Enzymes'?
Enzymes Enzymes are catalysts. Most are proteins. (A few rib nucleoprotein 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 catalyses. In doing so, they lower the amount of activation energy needed and thus speed up the reaction. Examples: * Catalyse. It catalyses the decomposition of hydrogen peroxide into water and oxygen. 2H2O2 -> 2H2O + O2 One molecule of catalyse can break 40 million molecules of hydrogen peroxide each second. * Carbonic anhydrase. It is found in red blood cells where it catalysis the reaction CO2 + H2O <-> H2CO3 It enables red blood cells to transport carbon dioxide from the tissues to the lungs. One molecule of carbonic anhydrase can process one million molecules of CO2 each second. * Acetylcholinesterase. It catalysis the breakdown of the neurotransmitter acetylcholine at several types of synapses as well as at the neuromuscular junction - the specialized synapse that triggers the contraction of skeletal muscle. One molecule of acetyl cholinesterase breaks down 25,000 molecules of acetylcholine each second. This speed makes possible the rapid "resetting" of the synapse for transmission of another nerve impulse. Most of these interactions
Too Much Information: Genetic Testing
Too Much Information: Genetic Testing Biology OAC ISP Essay - By Daniel Perez Genetic testing offers a whole new world of information about us and how our bodies work. The data we get from delving into our own genetic code can help us to cure or even prevent disease, stop medical conditions such as cancer or cystic fibrosis from even manifesting, or even correct these sorts of errors before birth, and many other beneficial uses. However, at this point in time, all of this is beyond us. We have no miracle cures, no 'magic bullet' with which to fight disease or genetic conditions, in fact, our understanding of the genetic code is so limited that it's as if we cannot see the forest for the trees. We have taken our first baby steps into understanding human genetics with the completion of the Human Genome Project, and now that we have the big picture, we can begin to interpret it. Through information gleaned from our DNA, we now know that there are certain medical conditions that are caused by certain patterns within the genes. Some examples of these genetic conditions include Tay-Sach's disease, Bloom syndrome, Deafness, cystic fibrosis, and many other diseases (http://www.einstein.edu/e3front.dll?durki=7158). Although many of these conditions are fatal, the ones that are not can be treated early, even before symptoms develop when possible, or if not treated, at least monitored
Visit report
Visit report Garson's Farm *Aspect 1 the main aspect:- GM crops *Aspect 2 :- Pesticides *Target audience:- AS and A Level Biology students * Word count 1,892 Introduction Garson's farm is a family owned farm that is situated in London. The farm started off growing vegetables for the small markets in London. When the supermarket chains took over there was a higher demand for mass fruit and vegetables which led to the small markets and small shops losing business and shutting down. The bigger industrial farms sold their fruit and vegetables to the new supermarkets and Garson's farm could not compete with big demands. This led to the farm looking for other ways to keep their farm business going. This led to the idea of pick your own fruit. Garson's farm has been successful pick your own fruit farm now for over 25 years. (1) On our visit to Garson's farm our tour guide and part owner of the farm spoke of some of the many problems of growing fruit and crops in general for farmers. Examples of these are, having to deal with crops and fruit killing diseases that attacks the plants as well as other pests. Bob Garson said "that it is almost imposable for the farm to go completely organic because of the disease that now exist in the soil from the many years of growing plants on the same piece of land." Another reason it is hard for farms to become completely organic and
Use of a Redox Indicator to show Dehydrogenase Activity
Use of a Redox Indicator to show Dehydrogenase Activity Hypothesis: As the temperature increases, the time taken for the colour change to occur will decrease. Introduction: Triphenyl tetrazolium chloride (also known as T.T.C) is an example of an artificial hydrogen acceptor. It is a redox indicator which is colourless when oxidised, however when reduced, it produces a red, insoluble precipitate called 'formazans'. T.T.C can therefore be used to investigate the enzyme activity of dehyrogenase enzymes by showing a colour change when they are present. The purpose of this experiment is to see what effect temperature has on the activity of dehydrogenase enzymes within yeast cells. Materials/Apparatus: * Actively respiring yeast suspension. This is prepared by adding 10g of dried yeast to 1dm3 of distilled water, followed by mixing in 50g of glucose. This mixture should be allowed to stand for 24 hours before the experiment takes place. * Tiphenyl tetrazolium chloride is used as a redox indicator to investigate the activity of dehydrogenase enzymes when yeast suspension is exposed to different temperatures. * Distilled water for the preparation of the yeast suspension. * Test tubes to place the mixture of yeast and T.T.C. * Test tube rack to allow the test tubes to stand upright in the water baths. * Incubator to allow enzyme activity to occur at different temperatures *
What is Homeostasis?
HOMEOSTATSIS Homeostasis is a very important biological function that occurs in all endotherms but not ectotherms. Endotherms have the ability to adjust their body temperature: they are not dependent on the surrounding temperature of the environment. Examples of endotherms are mammals: humans. Homeostasis works by using a process called negative feedback which works by adjusting a condition in the body so that the internal environment stays, on average, the same. It works using nerves. A receptor detects the change in the surrounding environment and sends nerve impulses to the centres in the brain, such as the medulla, which sends nerve impulses to glands or muscles to bring about an effect which will lower or increase a condition in the internal environment to keep it within certain limits. Homeostasis is used to control body temperature, blood glucose concentration and the water content of the blood. The body temperature in endotherms is controlled by dilation and contraction of arterioles, sweat and contraction of the erector pili muscles. This is called thermoregulation. When the temperature of the surrounding environment increases the internal environment must be decreased. To do this the arterioles dilate (vasodilation) so that more blood flows through the capillaries next to the skins surface. This means more heat can be released through the skin as the blood is
