Imagine you are walking down a dark alley in the middle of New York City late at night. From the other end of the alley walks an unsavory looking character. You pause and focus. You quickly survey your surroundings and notice that if trouble is at hand you have only one of two options – turn around and flee or physically defend yourself.
The mysterious man approaches, slightly nods his head at you as he passes and walks on his way. As you turn around to watch him leave you notice that your heart is beating faster and that you are sweating. “Funny”, you think to your self, “how my body seems to have a mind of its own. It’s as if my heart and sweat glands also knew that danger was at bay”.
With that thought in mind you continue on your way home as quickly as you can.
A Mind of Its Own
Have you ever wondered how your body ‘knows’ how to appropriately respond to various types of situations? Take, for instance, our fictitious nighttime encounter. Why did the man’s heart start to beat faster and why did he start to sweat. This wasn’t a conscious action, but rather a natural reaction. Somehow or other it is programmed into us to respond in this way.
The answer, it seems, is communication. As the following video demonstrates, there is a lot of communication going on inside of us – not just between our brains and the outside world, but internally between various cells and organs. As we shall see in a moment, this communication is a key aspect in how the body knows which proteins to build and when to build them.
But first, let’s watch see why our fictitious traveler’s body reacts when danger approached so that we can get a good introduction as to how cellular communication works.
The Cellular Wide Web
As you can see – the cell is a pretty impressive communication system. Cellular signals, however, do a lot more than let us know if we need to fight or flee – they help regulate a whole number of processes, including the creation of the right proteins at the right time – as the following videos show:
So the simple answer to our question is that the cell has various mechanisms by which it can send a signal that a particular protein is needed at a particular time. When that signal is sent then a process is started whereby the appropriate gene (i.e, that section of DNA which codes for that particular protein) is then ‘expressed’ – i.e., it is translated and transcripted into the needed protein.
Ready to Go
Well, for now we are done with our introduction to DNA. Of course, there is more to learn about DNA and we may have cause to revisit this series in the future. But for now I think we are ready to take on some other issues such as the origin of life, the neo-Darwinian Theory of Evolution and Irreducible Complexity.
See you in the next series.