Co-op Stories: Greg Zintz
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7.2 The eubacterial chromosome Some of the diverse roles of chromatin components can be illustrated by examining the E. coli chromosome. Like most prokaryotes, E. coli has a single chromosome consisting of a single double-stranded circular DNA molecule. There is no nucleus present, but the E. coli DNA is within a discrete entity in the cytoplasm called the nucleoid. The nucleoid contains a multitude of proteins and is in close proximity to the ribosomes, where translation occurs. In addition to
4.2 The reduction of chromosome number: meiosis If you look at the chromosomes shown in Figure 8 you will see that they have been lined up in pairs. The members of each pair are of similar shape and size, and unlike the members of other pairs. At a molecular level these distinctions are maintained: the order of the bases in the DNA is very similar in both members of a pair, but is quite different from that found in other pairs. By ‘very similar’ we mean that the order of the particular genes on each chromosome of the pair is the same,
4.1 Why are cells different? Now let us go on with our story and assume that we have decided the time is right to have a baby. The primary requirement for conception is that healthy gametes should be produced. We shall therefore look first at how gametes are made, and then examine some of the factors affecting their quality. But we must start with an explanation of what gametes are, and what sets them apart from other kinds of cell. In other words, what makes gametes special? Gametes are the cells that fuse to form a new
3.3.3 Mechanical methods of contraception While hormone-containing pills represent a very sophisticated kind of contraceptive, mechanical contraceptives are a straightforward idea: they act by preventing sperm and egg from meeting. Mechanical contraceptives in their simplest form have been around since before Roman times; some are shown in Figure 4. The earliest ‘penis protectors’ were allegedly used less for contraception than as protection against disease, and as a badge of rank. 1.2 Satellite systems and their origins The satellite systems of the giant planets have several features in common. Most satellites are in synchronous rotation, always keeping the same face towards their planet. Irregularly shaped moonlets associated with the ring system orbit closest to the planet. They travel in near-circular prograde orbits in the planet's equatorial plane. (‘Prograde’ in this sense means orbiting in the same direction as the planet's spin.) These moonlets (like the rings) are believed to be fragments of lar Introduction The plant predators, or herbivores, are a varied group, but they share certain characteristics. Many of them are large; among the smallest is the chevrotain (or mouse-deer) at about two kilograms weight, and the elephant is the largest, with a typical bull male weighing around six tonnes. In this unit we'll be looking in more detail at some of the problems and consequences of adopting a plant-eating way of life. Leaves are a much less nutritious food than most kinds of animal material, so lar 6 Reflection If you are working through all the units in this series, you'll be aware that this unit has taken a somewhat different tack from earlier ones. I've used rodents to explore some fundamental biological principles that have a relevance far beyond this particular order. It is especially appropriate to talk about issues such as biological success in connection with rodents, given their very wide geographical distribution and the very large number of rodent species and individuals. You'll recall (f 5.3 The effect of environment on reproductive behaviour Review your reading of Section 4.2 on the family life of marmots (or re 5.1.6 Pulling it all together The electric and magnetic fields given by Equations 7.21 and 7.23 can satisfy all four of Maxwell's equations in empty space. Gauss's law and the no-monopole law are immediately satisfied because the fields are transverse. Faraday's law and the Ampère–Maxwell law will also be satisfied if we can find electric and magnetic fields that obey Equations 7.24 and 7.26. We are looking for wave-like solutions, so it is sensible to try 3 Where do earthquakes occur? How deep in the Earth do earthquakes occur? Most earthquake foci are within a few tens of kilometres of the surface. Earthquakes less than 70 km deep are classified as shallow-focus. Earthquakes with foci 70–300 km deep are classified as intermediate-focus and those below 300 km are deep-focus (Figure 7). Shallow-focus 8 Magistrates Magistrates have been a part of the English legal system since the Justice of the Peace Act 1361. Their main role has always been in the criminal justice system. There are now over 30,000 magistrates (also known as Justices of the Peace) hearing over one million criminal cases per yea 3.2.1 Remarks By ‘contains’, we mean that we can find part of the surface that is homeomorphic to a Möbius band. The edge of the Möbius band does not need to correspond to an edge at the surface, so that a surface without boundary can be non-orientable (as we shall shortly see). When seeking Möbius bands in a surface, it can be helpful to look at all possible closed curves on the surface and thicken these into bands. Remember, fro 2.3.7 Two-fold torus As the polygons become more complicated, so the identifications become more difficult to visualise. For example, what happens if we try to identify the edges of an octagon in pairs, as indicated by the edge labels and arrowheads in Figure 34? Author(s): Studying Darwin Theologians in Conversaton; The Temple and the First Christians Earthquake and Fault line Model Video News Release: Nonprofit, Diversity Institutes to Address Community Needs
Activity 5
This unit brings together a collection of units from the OpenLearn site that would be of interest to anyone wishing to study Darwin’s theory of evolution and natural selection and how his work has gone on to influence other work around this theory. First published on Tue, 04 Dec 2012 as Author(s):
Margaret Barker and Tom O'Loughlin discuss the significance that the first followers of Jesus attached to the temple in Jerusalem, and how the imagery of the temple played a role in their developing understanding of Jesus and of their own identity.
Caro Begg demonstrates how to make a simple mechanical model to simulate faults, earthquakes and aftershocks. For primary or intermediate level. (03:40)
The College of Southern Maryland announces the formation of two community institutes to address critical individual and community needs within the region. As collaborative efforts bringing together various agencies and individuals and with funding provided by the Charles County Commissioners, the college will coordinate the efforts of the newly formed Diversity Institute at the College of Southern Maryland as well as the Nonprofit Institute at the College of Southern Maryland.
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