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
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7.1 Introduction

Until now, we have discussed DNA primarily as a double helix, but in its natural state within the cell it is found packaged as a complex mixture with many different proteins and other components. You have already seen examples of proteins with specific roles to play, such as topoisomerases and the proteins with various DNA binding domains, but in this section we will turn our attention to the proteins that serve to pack and organise the DNA into what we call chromatin.

The packaging of
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2.1.1 Ron revisited

In Case Report 1 you met Ron. Ron is 59 years old, has a BMI of 31 and a central obesity ratio of 0.96, indicating that he is moderately obese, with the fat concentrated in his abdomen, rather than his hips. Clearly a number of factors, some environmental, others relating to Ron's age and all interacting with Ron's genetic constitution, may help to provide an explanation. Let's look at some of these factors in a little more detail. It is clear that Ron enjoys a comfortable lifestyle with litt
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7.2 Types of active galaxy

  • All active galaxies have a compact, energetic nucleus – an AGN.

  • Seyfert galaxies are spiral galaxies with bright, point-like nuclei which vary in brightness. They show excesses at far infrared and other wavelengths, and have strong, broad emission lines.

  • Quasars resemble very distant Seyfert galaxies with very luminous nuclei. They are variable. About 10% are strong radio sources thought to be powered by jets of material
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7.1 The spectra of galaxies

  • The spectrum of a galaxy is the composite spectrum of the objects of which it is composed.

  • The optical spectrum of a normal galaxy contains contributions from stars and HII regions. An elliptical galaxy has no HII regions and has an optical spectrum that looks somewhat like a stellar spectrum but with rather fainter absorption lines. A spiral galaxy has both stars and star-forming regions, and its optical spectrum is the composite of its st
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Radio-loud AGNs

The second model (Figure 36b) is similar to the first, but now the engine is producing a pair of jets that will eventually end in a pair of lobes, as seen in radio galaxies and some quasars.

Looking at the model from the side, one expects to see narrow lines in the spectrum (but not broad lines) and two
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Introduction

There are a wide range of different interactions between ‘science and the public’. Examples range from visiting a museum, or indulging in a science-related hobby, to reading a newspaper article about a breakthrough in the technique of therapeutic cloning, to attending a protest meeting about plans to build a waste disposal unit near to a residential area. Some such interactions are largely one-way; being a member of the audience for a ‘go-hear’ lecture, visiting a museum or‘‘liste
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10 Risk assessment exercise

After reading this unit you might like to carry out a risk assessment of your office environment or a nearby office and one of the following:

  1. a display-screen user risk assessment;

  2. a laboratory-based risk assessment;

  3. a field-work risk assessment for a proposed field expedition.


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9.3 Health

The leader must be informed of any problems of mental or physical health that may affect safety during field-work. This may include, for instance, information on diabetes, asthma or epilepsy; students should also inform the leader if they require extra assistance. All work handling living organisms, soil or water may give some risk of infection, and protection in the form of gloves, masks, etc., may need to be carried. Supervisors should give advice concerning particular health hazards that m
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7.6 Personal protective equipment

Figure 12
Figure 12 Personal protective equipment (PPE) for working with highly corrosive liquids

In most laboratories, laboratory coats and
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7.5 Control measures

7.5.1 Control measures to avoid exposure

There are four main methods of exposure to chemicals:

  1. Inhalation – This is the main method of exposure to volatile solvents and gases.

  2. Skin absorption – Certain chemicals possess the ability to penetrate through pores of skin (for example, mercury compounds and hydr
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7.3 Disposal requirements

Figure 9
Figure 9 Disposal canister

When carrying out a risk assessment, you must consider disposal requirements. For example, any chemical d
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7.2 Information sources

7.2.1 How do I find the information required to carry out COSHH risk assessments?

The best source of information is the material safety data sheet (MSDS). By law (CHIP3) this should accompany any chemical that is purchased. However, if this is not available, or the chemical is old, then copies can be obtained from the manufacturer's website or information can sometimes be found in t
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7.1 Health problems associated with using chemicals

As described in Section 6.2, hazard is defined under COSHH as the inherently dangerous properties of a chemical or biological organism, and risk is defined as the likelihood of a chemical causing harm to people or to the environment.

There are several, more specific, known health problems associated with using chemicals.
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6.1 Control of Substances Hazardous to Health (COSHH) Regulations

For those companies involved in the handling of chemicals and/or biological material there are a number of additional regulations. These are known as the Control of Substances Hazardous to Health (COSHH) Regulations. These were introduced in 1988, and the last update was in 1999. These regulations apply to chemicals, biological hazards and dusts.

The essential requirements are that the employer must:

  • make an assessment of the health risk to empl
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5.2 Cryogenic liquids and ionising radiation safety

5.2.1 Cryogenic liquids

There are a number of hazards associated with cryogenic liquids, the main one being that when accidentally released the liquid expands hugely to form a gas (600 times in the case of nitrogen). The formation of such a large volume of gas can lead to asphyxiation in confined areas.

The other main hazard is cold burns (frostbite).

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4.2 Why do I need to know about first aid?

It takes only 3 to 4 minutes for a blocked airway to kill someone, but it can take more than 8 minutes for an ambulance to arrive on the scene. A simple procedure like opening an airway can save someone's life while you are waiting for professional help to arrive.

If you are working with harmful substances (chemicals, biological agents and dusts) you must know the first aid treatment if you are exposed. Do not expect a nurse or a doctor to know everything about every harmful substance.
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4.1 First aid

It is not required that students be trained in first aid. It is, however, important that a first aid kit is carried when you are likely to be away from immediate assistance. First aid must be rendered at once, and medical and relief help should be sought if necessary. It is important that appropriate first aid skills for use in the field are understood by those who might need them and that the procedures for enlisting help are known.

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3 Office safety

The relevant safety legislation for offices includes the Display Screen Equipment Regulations, which concern computer monitors and workstations. If electrical devices are used, then the Electricity at Work Regulations will apply. See Appendix A for a list of potential safety problems and considerations for offices and Appendix B for a checklist.

Click 'view document' to open Appendix A.

2 Legal requirements of health and safety in the UK

The Health and Safety at Work etc. Act (HSWA) 1974 states that:

  • It is the duty of every employer, so far as is reasonably practicable, to ensure the health, safety and welfare at work of all employees (this includes students).

  • It is the duty of every employee while at work to take reasonable care of himself (herself) and of other persons who may be affected by his (her) acts or omissions at work.

  • The employees must co
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