In the last part, we learned that DNA is the substance that is inside the nucleus of your cells. You've probably heard about DNA in the newspaper, on television, and on the very Internet itself. This entire website is based on DNA. But what is DNA? What is so special about the substance. When was it discovered? What does it do? These are probably some of the questions that are probably floating around in your head right now. Let's take another look at DNA so we can finally answer some of these mindbodgling questions.
Simply put, DNA is an acid that contain instructions on how to build and construct a plant, animal, or any living thing. It is inside the nucleus of nearly every cell in your body. It's hard to believe everything about you is within an acid. If you ever drank Coco-cola, then you have basically drank an acid.
Let's begin by taking an up close of DNA. Here is DNA shown through the eyes of an electron microscope. An electron microscope is a powerful tool. However, it still is limited in telling us about DNA.
What an electron microscope cannot do is give us information on how DNA can hold the "instructions" that is used by your cells to physically build and construct a living organism. The reason is that currently no microscope has the ability to peer that deep into a substance. So scientists had to turn to other means to get the answers they needed. What scientists knew is that somehow the structure of DNA is what is used by DNA to hold the "instructions" used by your cells. Because an electron microscope cannot help much, scientists turned to a technique that is still used today. It's called X-ray diffraction. Let's check it out.
X-ray is a technique that is used to describe the structure of substances. The way it works is cool. First, DNA is crystalized. Because DNA is crystalized, the atoms that make it up are frozen in place. Next, a beam of X-rays are shot into the DNA.
The X-rays bounce off the atoms and then make a pattern. This pattern is fed to a computer which figures out the position that each individual atom had to be in. The pattern the computer uses looks something like this shown toward your left.
When scientists first used X-ray diffraction, they got a picture like the one shown right above this paragraph you are reading. But there was a problem. At the time, no one had a computer that could figure out the actual structure of DNA.
So scientists had to manually figure out DNA's structure. This task fell upon two gentleman, Francis Crick and James Watson who in 1953, published the first true model of DNA.
In the next section, we are going to study the structure of DNA in greater detail. For the first time we are going to unlock the secrets of DNA and see how this substance is able to hold it's important information. But before we do that, let's take a look at the brief history of DNA. When did scientists first discover it. How was it discovered? Who discovered it? You'll be surprised when you find out the answers to these questions!!!!
Miescher then extracted a substance from the nuclei. He named this substance nuclein. Unfortunately, Mr Miescher never during his lifetime never figured out what nuclein actually was.
Like most discoveries in science, the discovery of DNA was by
accident. This guy by the name of Friedrich Miescher was working with white blood cells. He then began gathering pus
from the bandages of patients from a local hosptial. After using a salt solution to wash the pus from the bandages, and using an alkaline solution, the nucleus from those white blood cells were obtained.
It would take almost 70 years for nuclein to be fully understood. Until then, scientists were clueless about the inherited similarites between parents and offspring. Shown above is a nice little animation to show you. Check it out!!!!. Let's now move on to the next page. We will begin the next page by looking at structure of DNA as Crick and Watson envisioned it. Their monumental work has earned them a Nobel Peace Prize as they have rightfully earned it, as well as place in history.
Friedrich Miescher (1844-1895)
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