1 Wave energy The energy carried by ocean waves derives from a proportion of the wind energy transferred to the ocean surface by frictional drag. So, ultimately it stems from the proportion of incoming solar energy that drives air movement. Just how much energy is carried by a single wave depends on the wind speed and the area of ocean surface that it crosses; wave height, wavelength, and therefore wave energy, are functions of the distance or fetch over which the wind blows. Not surprisingly the ma
3.3 Uranium production and economics Table 3 lists the major uranium-producing countries. Currently, Canada (with 29% of global supply in 2003) is the world's largest producer of uranium, followed by Australia (21%), both having increased production since about 1980, whereas production from the USA, France, and South Africa has declined (
2.3.1 Geological mapping of coalfields Coalfields can be divided into two categories: exposed coalfields, where the coal-bearing strata outcrop at the surface, and concealed coalfields, where they are hidden beneath younger rocks. Exposed coalfields can be defined with considerable precision by surface geological investigations; indeed geologists recording field data still represent the cheapest exploration ‘tool’ available to the coal industry. In populated regions, the locations of coal outcrops are well
1.4 Coal-forming environments in the geological record Figure 5 simplifies a typical vertical succession of sedimentary rocks found in many coalfields. The sequence from the base of the section upwards reveals the following: When a mire starts to form, the first plants take root in underlying clays or sands that form the soil. Their r
4.5 Summary Targeting sequences at the N-terminus of proteins direct translation across the ER, and act as signals for import to the nucleus, mitochondrion and chloroplasts. Sequences at the C-terminus control traffic through the ER and the Golgi and to peroxisomes. Glycosylation is directed by signal sequences that act as targets for N-linked glycosylation in the ER and O-linked glycosylation in the Golgi apparatus. Glycosylation and remodelling of polys
3.6 Membrane fusion mediated by viral proteins Until now, we have focused on the transport of material between different intracellular membrane-bound compartments and fusion of cytoplasmic membranes. This type of fusion is endoplasmic fusion. Another type of membrane fusion, called ectoplasmic fusion, is used by enveloped viruses to infect cells (enveloped viruses have an outer phospholipid bilayer). The biophysical and structural studies of viral proteins involved in the processes of membrane fusion provide a foundation for
3.2 Formation of clathrin and COP-coated vesicles The structure of clathrin and clathrin-coated vesicles is known in some detail. Clathrin consists of a heavy chain of Mr 180,000 together with a light chain of Mr 35,000. Clathrin molecules successively assemble into a polyhedral, cage-like coat on the surface of the coated pit. The clathrin coat is made of sub-assemblies, each consisting of a three-pronged protein complex, a triskelion, each leg of which is made of one heavy and one light chain (Author(s):
2.7 Summary Eukaryotic cells contain numerous distinct types of membrane-bound compartment. Transport vesicles move proteins and other molecules between the compartments. Proteins contain signalling sequences or patches that specify their destination compartment. Proteins destined for lysosomes, secretion or the plasma membrane are synthesised in the ER, transported to the cis Golgi, modified in the Golgi apparatus, and sorted and pa
2.2 Traffic in the endoplasmic reticulum and the Golgi network The ER extends as a network of membranous tubes and sheets throughout the cytoplasm and is the site of synthesis of proteins ultimately destined for the Golgi apparatus, endosomes, lysosomes, the plasma membrane, secretory vesicles and beyond. In animal cells, the Golgi apparatus is usually a single structure located near the nucleus of the cell, consisting of between four and ten flattened cisternae, which are designated the cis, medial or trans Golgi network, depending on thei
4.1 Glucose metabolism We are now in a position to draw together the major concepts and components of signalling, and show how they operate in one well-understood system, namely the regulation of the storage or release of glucose in the human body. From this, you will be able to recognize archetypal pathways represented in specific examples, you will be able to appreciate how the same basic pathways can be stimulated by different hormones in different tissues, and you will see how opposing hormones activate separat
1.2. Getting started Registering is free and only requires a user name, email address and password. Sign up to iSpot.(Right-click on the link to open it in a new window or tab). Watch the video on how to register. 8.5 Line spectra: Activity 7 Colours and broad lines Read Peterson Sections 1.3.3 and 1.3.4 by clicking the link below. 3.8 Glucagon Glucagon is another hormone produced by the pancreas. Question: Can you recall which cells make glucagon? 1.7.2 End-of-unit questions
Table 8 shows the atmospheric pressure P in pascals (Pa) at various heights h above the Earth's surface. Plot a graph to give a visual representation of the data in the table. Be careful to label your axes co Introduction Motion is vital to life, and to science. In many ways it was the investigation of motion, initiated by Galileo Galilei in the late sixteenth century, and brought to a head by Isaac Newton in the seventeenth, that inaugurated the modern era of physics. Progress since that time has been so great that describing motion is now regarded as a fundamental part of science rather than one of its frontiers. Nonetheless, the description of motion played a central role in Einstein's formulation of the sp 5.3.4 Aye-ayes Perhaps with good reason, the aye-aye has been dubbed by some ‘the strangest of all primates’ and LoM provides some of the reasons [p. 243]. Little wonder that, as DA points out, the species was first classified as a rodent like them, it has powerful incisor teeth that grow continuously. 2.1 Differences between accuracy and precision Accuracy is a measure of how close a result is to the true value. Precision is a measure of how repeatable the result is. For instance, a group of three friends tried the shooting gallery at a fair and their targets are shown in Figure 6. The first person was an expert marksman, but they were using a rifle with sights that had not 2.5.3 The end of physics? Suppose for the moment that quantum field theory, or string theory or M-theory, or some other theory no one has yet heard of, does turn out to be the much sought-after superunified theory. Suppose it is unique and is so wonderfully compact that it can be printed on the front of a T-shirt. What would such a theory really tell us about the world? Looking on the positive side, the theory should indicate the fundamental entities of which the world is composed, whether they are particles, st 5.3 Mitochondrial adaptations During the winter months, whilst hibernating vertebrates maintain a very low metabolic rate, major reorganization of mitochondrial metabolism occurs. The phenomenon has been studied in some detail in frogs which, although not hibernators in the true sense, can endure very low water temperatures under the conditions of profound hypoxia that exist when they lie dormant for long periods below the surface. In contrast to normoxic conditions, the muscle mitochondria of dormant frogs depress their 4.4.1 Introduction Since its development, the three-way catalyst has been exposed to the full spectrum of techniques available for the characterisation of catalytic materials. The data provided can be correlated with the results of activity tests and kinetic measurements, which provide information on the performance of the catalyst. This reveals that although the catalyst functions as a composite material, it can be divided into distinct groups of catalytic centres that provide several different types of site,
Activity 7: Colours and broad lines
Question 25
