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If you went to college, your school likely had an official statement about plagiarism similar to this one from Oxford University: Plagiarism is presenting someone else’s work or ideas as your own, with or without their consent, by incorporating it into your work without full acknowledgement. All published and unpublished material, whether in manuscript, printed or electronic form, is covered under this definition.

The post Plagiarism or text recycling? It depends on the context. appeared first on OUPblog.

How does nature benefit our health? Many of us intuitively know that we simply feel better after ‘stepping out for some fresh air.’ Now over 30 years of research has begun to reveal exactly what health benefits we get from nature. Here are five reasons why we need to make space and time for nature in our lives.

The post Five ways nature can improve our health appeared first on OUPblog.

Molecular biology continues to inform science on a daily basis and reveal what it means to be human beings as we discover our place in the universe. With the ability to engage science in ways that were unimaginable only a few decades ago, we can obtain the genetic profile of a germ, discover the roots of unicellular life and uncover the mysteries of now extinct Neanderthals.

In One Plus One Equals One, author John Archibald unmasks the wonders of biotechnology, showing readers how evolution has interacted with the subcellular components of life from the beginning to present day. With molecular biology, we can look back more than three billion years to reveal the microbial activities that underpin the development of complex life, just as we can look at the inner workings of our own cells. Take a look around and ask yourself, how much do you know about the world around us?

Headline image credit: HINGOLGADH. Photo by Kalpeshzala59. CC BY-SA 3.0 via Wikimedia Commons.

The post The evolution of life appeared first on OUPblog.

        

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This is the latest post in our regular OUPblog column SciWhys. Every month OUP editor and author Jonathan Crowe will be answering your science questions. Got a burning question about science that you’d like answered? Just email it to us, and Jonathan will answer what he can. Today: how do organisms evolve?

By Jonathan Crowe

The world around us has been in a state of constant change for millions of years: mountains have been thrust skywards as the plates that make up the Earth’s surface crash against each other; huge glaciers have sculpted valleys into the landscape; arid deserts have replaced fertile grasslands as rain patterns have changed. But the living organisms that populate this world are just as dynamic: as environments have changed, so too has the plethora of creatures inhabiting them. But how do creatures change to keep step with the world in which they live? The answer lies in the process of evolution.

Many organisms are uniquely suited to their environment: polar bears have layers of fur and fat to insulate them from the bitter Arctic cold; camels have hooves with broad leathery pads to enable them to walk on desert sand. These so-called adaptations – characteristics that tailor a creature to its environment – do not develop overnight: a giraffe that is moved to a savannah with unusually tall trees won’t suddenly grow a longer neck to be able to reach the far-away leaves. Instead, adaptations develop over many generations. This process of gradual change to make you better suited to your environment is called what’s called evolution.

So how does this change actually happen? In previous posts I’ve explored how the information in our genomes acts as the recipe for the cells, tissues and organs from which we’re constructed. If we are somehow changing to suit our environment, then our genes must be changing too. But there isn’t some mysterious process through which our genes ‘know’ how to change: if an organism finds its environment turning cold, its genome won’t magically change so that it now includes a new recipe for the growth of extra fur to keep it warm. Instead, the raw ‘fuel’ for genetic change is an entirely random process: the process of gene mutation.

In my last post, I considered how gene mutation alters the DNA sequence of a gene, and so alters the information stored by that gene. If you change a recipe when cooking, the end product will be different. And so it is with our genome: if the information stored in our genome – the recipe for our existence – changes, then we must change in some way too.

I mentioned above how the process of mutation is random. A mutation may be introduced when an incorrect DNA ‘letter’ is inserted into a growing chain as a chromosome is being copied: instead of manufacturing a stretch of DNA with the sequence ATTGCCT, an error may occur at the second position, to give AATGCCT. But it’s just as likely that an error could have been introduced at the sixth position instead of the second, with ATTGCCT becoming ATTGCGT. Such mutations are entirely down to chance.

And this is where we encounter something of a paradox. Though the mutations that occur in our genes to fuel the process of evolution do so at random, evolution itself is anything but random. So how can we reconcile this seeming conflict?

To answer this question, let’s imagine a population of sheep, all of whom have a woolly coat of similar thickness. Quite by chance, a gene in one of the sheep in the population picks up a mutation so that offspring of that sheep develop a slightly thicker coat. However, the thick-coated sheep is in a minority: most of the population carry the normal, non-mutated gene, and so have coats of normal thickness. Now, the sheep population live in a fairly tempera

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This is the third post in our latest regular OUPblog column: SciWhys. Every month OUP editor and author Jonathan Crowe will be answering your science questions. Got a burning question about science that you’d like answered? Just email it to us, and Jonathan will answer what he can. Today: How is the information in a gene used by a cell?

By Jonathan Crowe

In my last two posts I’ve introduced the notion that DNA acts as a store of biological information; this information is stored in a series of chromosomes, each of which are divided into a number of genes. Each gene in turn contains one ‘snippet’ of biological information. But how are these genes actually used? How is the information stored in these genes actually extracted to do something useful (if ‘useful’ isn’t too flippant a term for something that the very continuation of life depends upon).

Many (but not all) genes act as recipes for a family of biological molecules called proteins: they literally tell the cell what the ingredients for a particular protein are, and how they should be combined to create the protein itself. (Proteins have a range of essential roles in the human body. Some act as building materials for different components of the body, such as the keratin we find in our hair and nails. Others act as molecular transporters: haemoglobin, which is found in our red blood cells, carries oxygen from our lungs to other parts of the body. A family of proteins called the enzymes are arguably the most important, however. Enzymes cajole different chemicals in our body into reacting with one another. Without enzymes, our bodies would be unable to generate energy from the food we eat (and you’d not be reading this blog post).)

So, somehow, the information stored in a DNA molecule is deciphered by the cell and used as the recipe for a protein. But how?

To answer this question, let’s take a journey inside the cell. We can imagine a cell to be like a factory, but one that has been divided into a series of physically separated compartments. Unlike a factory filled with air, a cell is filled with a jelly-like fluid called the cytoplasm, which surrounds the various compartments enclosed within it. In an earlier post I likened a genome to a biological library. And, inside the cell, this library is stored within a particular compartment called the nucleus.

I mentioned earlier that genes often act as recipes for proteins. But here comes a bit of a quandary: chromosomes – and the genes they contain – are locked away inside the cell’s nucleus. By contrast, proteins are manufactured by the cell in the cytoplasm, outside of the nucleus. So, for the genetic information to be used, it has to get out of nucleus and into the cytoplasm. How does this happen? Well, if we’re in a library with a book that contains information we really need, but we’re unable to take the book out of the library, we might make a photocopy of the page that holds the information we’re after. To get the information it needs out of the nucleus and into the cytoplasm the cell does something remarkably similar. The chromosome containing the gene of interest has to stay inside the nucleus, so the cell makes a copy of the gene – and that copy is then transported to where it is to be used: out of the nucleus and into the cytoplasm.

The copy of the gene generated during this cellular photocopying is made not of DNA but of a close cousin called RNA. RNA is made of three of the same building blocks as DNA – A, C and G. Instead of the T found in DNA, however, RNA uses a different block represented by the letter U (for ‘uracil’). Despite this

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This is the second post in our latest regular OUPblog column: SciWhys. Every month OUP editor and author Jonathan Crowe will be answering your science questions. Got a burning question about science that you’d like answered? Just email it to us, and Jonathan will answer what he can. Today: What are genes and genomes?

By Jonathan Crowe

I described in my last blog post how DNA acts as a store of biological information – information that serves as a set of instructions that direct our growth and function. Indeed, we could consider DNA to be the biological equivalent of a library – another repository of information with which we’re all probably much more familiar. The information we find in a library isn’t present in one huge tome, however. Rather, it is divided into discrete packages of information – namely books. And so it is with DNA: the biological information it stores isn’t captured in a single, huge molecule, but is divided into separate entities called chromosomes – the biological equivalent of individual books in a library.

I commented previously that DNA is composed of a long chain of four building blocks, A, C, G, and T. Rather than existing as an extended chain (like a stretched out length of rope), the DNA in a chromosome is tightly packaged. In fact, if stretched out (like our piece of rope), the DNA in a single chromosome would be around 2-8 cm long. Yet a typical chromosome is just 0.00002–0.002 cm long: that’s between 1000 and 100,000 times shorter than the unpackaged DNA would be. This packaging is quite the feat of space-saving efficiency.

Let’s return to our imaginary library of books. The information in a book isn’t presented as one long uninterrupted sequence of words. Rather, the information is divided into chapters. When we want to find out something from a book – to extract some specific information from it – we don’t read the whole thing cover-to-cover. Instead, we may just read a single chapter. In a fortuitous extension of our analogy, the same is true of information retrieval from chromosomes. The information captured in a single chromosome is stored in discrete ‘chunks’ (just as a book is divided into chapters), and these chunks can be read separately from one another. These ‘chunks’ – these discrete units of information – are what we call ‘genes’. In essence, one gene contains one snippet of biological information.

I’ve just likened chromosomes to books in a library. But is there a biological equivalent of the library itself? Well, yes, there is. Virtually every cell in the human body (with specific exceptions) contains 46 chromosomes – 23 from each of its parents. All of the genes found in this ‘library’ of chromosomes are collectively termed the ‘genome’. Put another way, a genome is a collection of all the genes found in a particular organism.

Different organisms have different-sized genomes. For example, the human genome comprises around 20,000-25,000 genes; the mouse genome, with 40 chromosomes, comprises a similar number of individual genes. However, the bacterium H. influenzae has just a single chromosome, containing around 1700 genes.

It is not just the number of genes (and chromosomes) in the genome that varies between organisms: the long stretches of DNA making up the genomes of different organisms have different sequences (and so store different information). These differences make sense, particularly if we imagine the genome of an organism to represent the ‘recipe’ for that organism: a human is quite a different organism from a mouse, so we would expect the instructions that direct the growth and function of the two organisms to differ.

B

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Today we’d like to introduce our latest regular OUPblog column: SciWhys. Every month OUP editor and author Jonathan Crowe will be answering your science questions. Got a burning question about science that you’d like answered? Just email it to us, and Jonathan will answer what he can. Kicking us off: What is DNA and what does it do?

By Jonathan Crowe

We’ve all heard of DNA, and probably know that it’s ‘something to do with our genes’. But what actually is DNA, and what does it do? At the level of chemistry, DNA – or deoxyribonucleic acid, to give it its full name – is a collection of carbon, hydrogen, oxygen, nitrogen and phosphorus atoms, joined together to form a large molecule. There is nothing that special about the atoms found in a molecule of DNA: they are no different from the atoms found in the thousands of other molecules from which the human body is made. What makes DNA special, though, is its biological role: DNA stores information – specifically, the information needed by a living organism to direct its correct growth and function.

But how does DNA, simply a collection of just a few different types of atom, actually store information? To answer this question, we need to consider the structure of DNA in a little more detail. DNA is like a long, thin chain – a chain that is constructed from a series of building blocks joined end-to-end. (In fact, a molecule of DNA features two chains, which line up side-by-side. But we only need to focus on one of these chains to be able to understand how DNA stores its information.)

There are only four different building blocks; these are represented by the letters A, C, G and T. (Each building block has three component parts; one of these parts is made up of one of four molecules: adenine, cytosine, guanine or thymine. It is these names that give rise to letters used to represent the four complete building blocks themselves.) A single DNA molecule is composed of a mixture of these four building blocks, joined together one by one to form a long chain – and it is the order in which the four building blocks are joined together along the DNA chain that lies at the heart of DNA’s information-storing capability.

The order in which the four building blocks appear along a DNA molecule determines what we call its ‘sequence’; this sequence is represented using the single-letter shorthand mentioned above. If we imagine that we had a very small DNA molecule that is composed of just eight building blocks, and these blocks were joined together in the order cytosine-adenine-cytosine-guanine-guanine-thymine-adenine-cytosine, the sequence of this DNA molecule would be CACGGTAC.

The biological information stored in a DNA molecule depends upon the order of its building blocks – that is, its sequence. If a DNA sequence changes, so too does the information it contains. On reflection, this concept – that the order in which a selection of items appears in a linear sequence affects the information stored in that sequence – may not be as alien to us as it might first seem. Indeed, it is the concept on which written communication is based: each sentence in this blog post is composed of a selection of items – the letters of the alphabet – appearing in different sequences. These different sequences of letters spell out different words, which convey different information to the reader.

And so it is with the sequence of DNA: as the sequence of the four building blocks of DNA varies, so too does the information being conveyed. (You may well be asking how the information stored in DNA is actually interpreted – how it actually determines how an organism develops and functions – but that’s a topic for a different blog post.)

You may be wondering how on earth ju

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By Jonathan Crowe

It began with the sound of a tyre rim grinding on the surface of the cycle path I’d been travelling along, and a sudden sensation of being on a bike that was moving through treacle rather than through air. My rear tyre had punctured and, not for the first time of late, I found myself resenting the seeming futility of life: of having the bad luck to get the puncture, of having to spend time and effort buying and fitting a new inner tube – of my life being enriched not one iota by the whole experience.

As I trudged home that evening, wheeling the now-useless bike beside me, I reflected on the many situations we encounter that mirror this experience – when we find ourselves having to invest energy, only to be no further forward, in real terms, having done so.

Why is it that we have to invest energy merely to maintain the status quo? Why do we find ourselves running, effectively only to stand still? The answer lies in an intrinsic property of all matter, a universal truth so fundamental to our existence that it is captured by its own law: the Second Law of Thermodynamics. This law tells us, in a nutshell, that we are living in a perpetual downward spiral, in which things just get worse. A cheery outlook on life, if ever there was one. But it is an outlook from which there is no escape: the universe, and everything in it, is gradually crumbling into a state of ever-increasing disorder.

This property of all matter – this collapse into disorder – is given a name: entropy. Things that are disordered have greater entropy than things that are relatively more organized. A glass of water, in which the molecules of water itself can move around relatively freely, is more disorganized – has greater entropy – than a block of ice, in which the molecules of water are trapped into a rigid, organized array.

A process that increases disorder, with its associated increase in entropy, is a spontaneous one: one that happens without having to do work to bring it about. This fact has one important corollary: a decrease in entropy – a move towards a more organized state – requires us doing work to bring it about. This is arguably why housework feels like a chore: a living room doesn’t spontaneously tidy itself. We need to invest effort to reverse the spread of disorder, and bring order to whatever degree of chaos had befallen our living space since we last made the effort to tidy up. We are essentially swimming against the natural tide of entropy, with disorder setting in the moment we take our foot off the pedal.

When we look at life at the scale of the molecules and cells of our bodies we continue to see an ongoing battle with entropy: a tussle between order and disorder. Consider proteins, the molecular machines that carry out many important functions in the cell. As they are first being manufactured (or ‘synthesised’) in the cell, proteins exist as elongated chains of conjoined amino acid subunits, much like links of sausages as they are extruded from a sausage-making machine. However, these elongated protein chains must fold into specific three-dimensional shapes to function correctly. This folding represents an increase in order, and hence a decrease in entropy. As we note above, though, swimming against the tide of entropy comes at a cost: the cell must do work to drive such a process forward.

This battle against entropy is essentially why we must eat on a regular basis: to give the cells of our body the energy they need to drive forward those processes that won’t happen spontaneously.

Even the very continuation of life is a battle against disorder. Successful reproduction relies on the passing of biological information from one generation to the next. Every time a cell divides, it must pass on a copy of its