Introduction Both vitamins and minerals are essential in the diet in small quantities.The term ‘vitamin’ was not coined until early in the 20th century, to describe those chemicals in food without which a pattern of deficiency symptoms (often called a deficiency syndrome) occurs. Minerals, also called mineral elements, are those elements other than carbon, hydrogen, oxygen and nitrogen that are found in the body. This unit looks at the two main groups of vitamins: the fat-soluble vitamins A, D,
Acknowledgements Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence All other materials included in this unit are derived from content originated at the Open University. 1. Join the 200,000 studen
9 Summary In this unit you have found out that: The sensation of pain is caused by the release of a chemical (prostaglandin) that stimulates the nerve endings and sends an electrical message to the brain. Pain can be reduced if the formation of prostaglandin can be inhibited. Prostaglandin is formed, from arachidonic acid, in a cavity in the active site of the enzyme cyclooxygenase (COX). Geometrical isomerism
1.8 Enter aspirin! Aspirin is able to release part of its ester group (Figure 15) in a hydrolysis reaction. Look again at the structure of aspirin, 2.8, and identify this group on the molecule. It is known as an acetyl group and accounts for aspirin also being called acetylsalicylic acid. The acetyl group on aspirin is fairly easily removed and can be available for forming another ester with an —OH group on another molecule; in this case, part of the structure that makes up the inside of the cavi
1.5 Some chemistry involving esters Esters are produced by the reaction of a carboxylic acid with an alcohol and result from the formation of a new bond (Reaction 2.1). For example, ethyl butanoate, the major constituent of artificial pineapple flavouring, is made from the reaction of butanoic acid with ethanol.
There is a certain l
1.4.3 Aspirin Compare the structure of aspirin, 2.8, with that of salicylic acid, 2.7. What similarities and differences can you see?
Author(s): 1.4.2 The functional group approach It is the classification of functional groups that simplifies the study of organic chemistry (the chemistry of compounds that contain carbon). With many millions of known organic compounds, and more being added by the day, it would be hopeless if their properties could not be systematised in some way. It turns out that a given functional group usually has the same chemical properties whatever carbon chain it is bonded to, so once the general properties of each functional group are known, all 1.4.1 Salicylic acid The structural formula of salicylic acid, 2.1, looks quite complicated. However, it becomes less daunting if you unpack it a bit. One of the first things to do when confronted with an unfamiliar structure is to check that all the valencies are correct (four for carbon, two for oxygen and one for hydrogen). If any atoms have the wrong valency, it follows that there is a mistake somewhere and the molecule does not exist as drawn. It looks OK for the structure of salicylic acid. You proba 1.3 The aspirin story As long ago as 400 BC the physician Hippocrates, from the island of Kos (now a popular Greek holiday destination) prescribed a concoction made from willow leaves to help relieve the pain of childbirth. Ever since then (and probably even before) herbal remedies based on the leaves or bark of willow trees have been used for the alleviation of pain and fever. In the 1840s the chemists of the day were able to extract the substance salicin from the bark of willow trees by treating it with boiling 1.2.1 The human genome: chromosomes and genes Almost all of the different types of cell in an individual contain the same genetic material in the chromosomes, as a consequence of mitosis. You had a glimpse of the appearance of the 46 human chromosomes in Figure 1.1, and in this unit we examine their size, shape and genetic composition. Chromosomes can be regarded as strings of genes arranged along their length, rather like beads on a thread. Each gene consists of a short section of the DNA that runs the full length of each chromoso Learning outcomes After studying this unit you should understand: that genes are the units of inheritance for individual characteristics and also may contribute to susceptibility to certain diseases; the number of chromosomes that make up the human genome and where they are located within the cell; something of the immense scale of the human genome project; how gametes are produced by the process of meiosis and how the full complement of 46 chromosomes 1.7.1 Research methods in context Any established discipline has a tradition of practice. Many disciplines have established methodologies which prescribe the selection, combination and sequencing of the methods and techniques to be employed. Others select methods and techniques less prescriptively and borrow more broadly across domain boundaries. All disciplines require an appropriate application of methods, in order to ensure rigour. Hence, one key skill is the demonstration of an appropriate knowledge and competence 2.4 Other spectrographs Although the simple, single-slit spectrograph described above is the type you are most likely to find on a small telescope, there are other more complex designs available. Each of these has its own role to play in astronomical observations. An echelle spectrograph has a second dispersing element, either a second grating or a prism, which disperses the light at right angles to the direction of dispersion produced by the main grating. Without going into details, the effect is to pr Acknowledgements Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence Grateful acknowledgement is made to the following sources for permission to reproduce material within this unit. 4.2 Earthquake magnitude The magnitude of an earthquake is a measure of the amount of seismic energy released by it, so it is a quantitative scale. The scale of earthquake magnitude is called the Richter scale. Its development is described in Box 4, Charles Richter and the Richter earthquake magnitude scale. The Richter magnitude 1.3.2 Search Engines and Subject Gateways Although both search engines and subject gateways will help you find the resources that you need, the types of information that you find will differ. Search engines such as Google and Yahoo! search the internet for keywords or phrases, and then show you the results. These results are not mediated by the search engines, and therefore you need to use your own judgement on the reliability of the results. You may, for example, find websites written by experts, alongside websites written by 1.3.1 Introduction You can find a lot of information about science and nature on the internet. To find this information you might choose to use: search engines and subject gateways; books and electronic books; databases; journals; encyclopedias. news sources internet resources References 4.13.3 Scrutiny Again, connected to the accountability issue is the problem of adequate scrutiny. The detailed, technical and specific nature of much-delegated legislation means that, on the whole, Members of Parliament (the elected representatives) do not have the expertise to consider proposed legislation effectively. In addition, you have already noted that the scrutiny committees themselves only have limited powers. 4.10 Parliamentary control Initially, Parliament has control in that the enabling or parent Act passed by Parliament sets out the framework or parameters within which delegated legislation is made. In addition, there are scrutiny committees in both Houses of Parliament whose role is to consider the delegated powers proposed by a Bill. However, these committees have limited power. European legislation is considered by a specific committee and local authority byelaws are usually subject to the approval of the Department
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