When you think about DNA, you might picture the double helix, or perhaps you think about genes and inherent traits. But what is DNA really, and how does it work? DNA is short for deoxyribonucleic acid, and it’s the molecule that contains the genetic instructions of a living organism. Those instructions are stored inside each cell, encoded in the DNA.
DNA is made of two long strands that wind around each other like a spiral staircase. Those two strands are held together by smaller molecules called nucleotides, which are arranged in a specific order. That order contains the instructions for making proteins, which do most of the work in our cells.
The DNA molecule is so small that it can only be seen with a powerful microscope. But inside each of our cells, there are about 2 meters (6.5 feet) of DNA! If you stretched out all the DNA in your body, it would reach from the earth to the sun and back – about 100 times!
The instructions stored in DNA are used to make proteins. But proteins are not just responsible for our physical traits, like the color of our eyes or hair. Proteins also perform many important tasks in our cells, like helping to break down food, repair damaged cells, and fight infection.
The History of DNA
The discovery of the structure of DNA is one of the most important scientific breakthroughs in history. It all started with a simple observation by a Swiss doctor named Friedrich Miescher in 1869. Miescher was studying cells from the pus of surgical wounds, and he noticed a substance inside the cells that didn’t seem to be like the other cell parts. Miescher named that substance nucleic because it was found in the nucleus of cells.
From the history of DNA, four scientists stand out: Johann Friedrich Miescher, Gregor Mendel, Frederick Griffith, and James Watson. Miescher was the first to discover DNA in 1869, but he didn’t know what it was or what it did.
In 1865, Gregor Mendel discovered the laws of inheritance, which explained how traits are passed down from parents to their children. But Mendel didn’t know what carried those instructions.
In 1928, Frederick Griffith was trying to figure out how a deadly disease called pneumonia was passed from one generation of mice to the next. He discovered that something in the blood of sick mice could make healthy mice sick.
Types of DNA
There are two types of DNA: nuclear DNA and mitochondrial DNA.
Nuclear DNA is the type of DNA that contains the instructions for making proteins. It’s found in the nucleus of cells, where most of the cell’s activity occurs.
Mitochondrial DNA is a type found in mitochondria, which are organelles that provide energy for the cell. Mitochondrial DNA is different from nuclear DNA in a few ways. First, it’s much shorter. Second, it’s not passed down from parents to their children in the same way that nuclear DNA is. Instead, mitochondrial DNA is passed down from mothers to their children.
When it comes to DNA is responsible for the physical traits of a living organism, and it is passed down from parents to their children. The history of DNA stands with Johann Friedrich Miescher, Gregor Mendel, Frederick Griffith, and James Watson as the most important scientists in its discovery.