2.1 Finding and extracting coal Coal is often regarded as the principal fossil fuel, and with good reason. There is almost three times more energy available from the global proven coal reserves as there is from proven oil and gas reserves taken together. Therefore, it is unsurprising that even today much time and effort is spent locating it. This section considers the techniques used in coal exploration and how coal is produced from surface and underground mines. But first, a brief look at a few of the historical aspe
Acknowledgements Grateful acknowledgement is made to the following: 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 Figures 4 and 8 Alber
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7.3 Regulation of secretion Up to this point we have made a clear distinction between constitutive secretion and regulated secretion. In reality however the border is a bit more blurred. For example, many molecules are constitutively expressed on the surface of a cell, but their expression is increased in response to a particular stimulus. In other words, surface expression is determined by both constitutive and regulated secretion. Constitutive secretion is regulated primarily at the level of protein synthesis, whereas
1.2 Polymerisation and depolymerisation of actin Actin is a highly conserved protein. Most organisms have several genes encoding actin; in humans there are six principal isoforms, four of which are found in different types of muscle and the other two (β and γ) in all non-muscle cells. (The term ‘isoform’ describes variants of a protein. These may be produced by different genes, or by differential splicing of the mRNA, or be generated by post-translational modifications.) The β and γ cytoskeletal forms differ by just four amino acid
1.3 Protein secondary structure From our consideration of the steric constraints that apply to peptide bonds and amino acid residues in a polypeptide, we have already begun to discuss some of the factors that determine how the backbone of the polypeptide folds. The conformation adopted by the polypeptide backbone of a protein is referred to as secondary structure. Whilst it is true to say that all proteins have a unique three-dimensional structure or conformation, specified by the nature and sequence of their amino a
Learning outcomes By the end of this unit you should be able to: define and use each of the terms printed in bold in the text; describe the different levels of protein structure and their interdependence; explain how steric limitations determine secondary structure in polypeptides; describe, using examples, the relationship between protein structure and function; understand the significance of domains in protein function and how t
1.1 So what's it all about? iSpot is a website aimed at helping anyone identify anything in nature. Once you've registered, you can add an observation to the website and suggest an identification yourself or see if anyone else can identify it for you. You can also help others by adding an identification to an existing observation, which you may like to do as your knowledge grows. Your reputation on the site will grow as people agree with you identifications. You may also like to visit our forums which offer lively debat
5 The Scopes monkey trial This section was written by Gary Slapper. In 2007, Professor Michael Reiss, a Church of England priest and the head of science at London's Institute of Education, said that it is becoming more difficult to teach evolution in schools because of the spread of creationism. Similar debate has long been burning in the United States. Also in 2007, a creationist museum opened near Cincinnati, where children in animal skins play amid model dinosaurs, suggesting they once coexisted and th
2 The biology of prions The increasing interest in kuru during the 1950s and 1960s had the effect of stimulating research into TSEs in humans and other animals. Summarise, in general terms, the possible causes of disease in animals. 1.5 BSE and risks to human health: vCJD Given this background, it is not surprising that the possibility that BSE in cattle might pose a health risk to humans was given serious consideration from a very early stage in the outbreak. Various precautionary measures intended to eradicate BSE in cattle and also to prevent any possibility of transmission of the disease to humans were introduced. We will discuss these in more detail later in the unit. At the same time, the public was repeatedly assured by both officials (e.g. the C 1.3.3 Position–time graphs Tables do not give a very striking impression of how one thing varies with respect to another. A visual form of presentation, such as a graph, is usually much more effective. This is evident from Figure 7, which shows the graph obtained by plotting the data in Table 2 and then drawing a smooth curve through the resulting points. 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 The following appears in Introduction to Astrobiology (Planetary Science Book 2: ISBN 0-521-54621-4) which is published in ass 3.6 The numbers game … or the struggle for existence In the majority of The Life of Mammals TV sequences there is relatively little evidence of any struggle for existence, apart from the occasional predator/prey interaction. Even then you are offered the comforting reassurance that ‘four out of five chases end with the prey escaping’. So you could be forgiven for thinking that most mammals survive to a ripe old age, or at least until, like the topi, they have fulfilled their reproductive potential. Not so! Four out of five chases may 3.2 Adaptation If you are working through the units in this series in sequence, you have already been introduced to the idea that many features of an animal's behaviour and structure are adaptations to their way of life. Unit S182_2 looked at the oily fur and the flipper-like feet of the water shrew, comparing the water shrew to the common shrew, a close relative that does not have these features and that does not chase prey under water. We also thought very carefully about the way that adaptations are desc 1 The rodent As you work through this unit you will come across boxes, like this one, which give you advice about the study skills that you will be developing as you progress through the unit. To avoid breaking up the flow of the text, they will usually appear at the start or end of the sections. As well as the un 2.1 Mammalian dentition Insects are generally very small animals. Many kinds are hard work to collect and not very nutritious because a high proportion of their mass is a protective and indigestible outer layer, called cuticle. Insectivorous mammals need to eat large numbers of insects to fulfil their energy requirements. Insect eaters have diverse ways of catching and dealing with their prey; teeth play a crucial role. Indeed, teeth are of such enormous significance to mammalian diets in general (and are so r 6.2.4 The speed and direction of the Earth's motion The first significant claim to have detected the motion of the Earth relative to the ‘frame of isotropic 3 K radiation’ came in 1977 from a group at Berkeley, California. They concluded that the Earth is moving at a speed of (390 ± 60) km s−1, in a direction towards the constellation Leo, relative to a frame in which the 3 K radiation is isotropic. Their conclusion resulted from observations of a variation of intensity with angle of the form predicted by Equation 14, which w Learning outcomes By the end of this unit you should be able to: define and use in context, or recognise definitions and applications of, each of the terms printed in bold in the text; identify some of the reasons why clean, fresh water is an increasingly scarce resource for many people in the world; explain what is meant by the bioaccumulation of xenobiotic chemicals and identify the implications that this has for what people can safely eat; di Introduction This unit examines why water shortages are predicted as a result of the world's growing population and the importance of access to clean and safe drinking water in public health. It looks at the distribution of water throughout the world and problems with contamination, topics of wide general interest. Introducing health sciences: a case study approachI
(SDK125) 1.10 Subtraction of decimal numbers Subtraction of numbers can be used to answer questions such as ‘what's the difference between two values?’ or ‘if something has decreased by a certain amount, what's its new value?’ Subtraction can also be thought of as undoing the process of addition. For instance, instead of saying ‘£10 take away £7.85 leaves how much?’ you could say, ‘what do I have to add to £7.85 to get back to £10?’
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