Keep It Simple Students: How You Were Copied

In the latest in the Keep It Simple Students series, 18-tear-old biochemistry student Henry Laney walks us through the deceptively simple way we are copied from DNA.

DNA is EZ. It's a single molecule that holds the blueprint for all of us. Two sets were randomly halved, and then combined with each other. And from this, you were copied into existence. Simple enough, right? Biochemistry is easy! Wait, don't leave! Hear me out. Although biochemistry may look impenetrable at the start, if you understand the simple processes, the more complex ones start to fall out as well. Soon after, a whole world of wonder opens up before you, and before you know it, you're in a dingy flat with no money in your pockets, or memory of the last time you ate something other than instant noodles, and you realise that you are now a postgraduate.

So, the basics.

DNA replication is merely the interaction of the molecule itself and some proteins. If that still sounds incredibly dull to you, think about it this way. Each cell in your body carries your entire genome-all your genes. Bits of the genome are turned on or off in each cell to give it a different function, so the cells in your eye are different from the cells in your teeth, which is why teeth don't tend to grow in your eye, which is generally agreed to be a good thing.

To go from instruction to construction, your body needs new cells. New cells need new DNA, and this genetic code is literally who you are. This is the case for every human, animal and plant on Earth. And if that doesn't interest you, nothing will.

DNA is, as most of you probably know, a double helix structure made of two strands, joined in the middle. Pay attention here: it's the bit in the middle that important! Those coloured lines represent the four bases Adenine (A), Cytosine (C), Guanine (G), and Thymine (surprisingly, T). Each base is attached to another one, making a base pair. But like couples at a house party, each base will only attach to its partner. C will only pair with G, and A will only pair with T. They're in exclusive relationships, if you will.

Each strand of the DNA molecule has a special sequence of bases, for example, AGCTATCGA. Now, because of pairing, the other strand will have to be as shown below.

AGCTATCGA

TCGATAGCT

"That's neat, but what does it have to do with me?" I hear you cry. Well, remember that the DNA in your genome is who you are. The information in the genetic code corresponds to everything that happens in your body, but it has to be read. The workhorses who turn information into reality are proteins. They help muscles to move, they help you to think, me to write, and pretty much everything else in between. The information in the genes is a code used to make proteins.

The building blocks of protein are called amino acids, and the "primary sequence" of a protein is a big long chain of amino acids. This sequence folds in a specific way (because of attractions between the different amino acids) to give each protein a unique structure. This structure (or shape) is directly related to the function (or job) of the protein. DNA is linked to proteins, because in the genetic code, three base pairs correspond to a single amino acid in the protein.

So, a strand of the DNA is read (by a protein), the information relayed to another part of the cell (by another protein), and a sequence of amino acids is made (in a process which, you may be shocked to hear, involves some more proteins), which finally folds into a protein. The constructed proteins then go on to do their DNA-determined jobs.

That's it. Those are the basics. And replicating DNA itself is actually fairly simple. Another protein unzips a gene to expose two naked sequences of DNA base pairs that the cell wants copied. Then, new bases are added according to the base pairing rules explained above. This requires two proteins, a single "loader" which supplies new bases, and two "assemblers" -one for each strand-which attaches them.

As a result two new, identical strands of DNA are formed. And that's it! Easy, informative and fun!

I don't know about you, but when I first learned about it, the process seemed like it would be rather slow. NOPE.

That video shows happenings in real time throughout your body. Without any effort on your part whatsoever, a fascinating and intricate process is copying an entire library of information about you billions of times over. And, even more amazingly, this wasn't designed. It evolved in a massive feedback loop going back billions of years. Simple.

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Henry Lloyd Laney is an 18-year-old student currently taking a year out before applying to university for biochemistry and working in the molecular genetics department of his local hospital. Don't try and talk to him about biochemistry. You won't escape. Ever.