How do they extract DNA from super old bones?

Question

very confused as to what DNA is, and have no technical expertise to understand detailed articles! Is DNA something you can look at under a microscope or what?

In: 8

Answer 1

DNA is a molecule that’s a really long chain made up of smaller units called nucleotides. It’s like a string of pearls with four colors (for different nucleotides). The sequence is used as a template to build all the proteins of the body, and guide the development of a single cell into a fully formed mature living thing.

You can’t see DNA under a normal microscope. Sometimes you can see chromosomes where DNA is wrapped around nuggets of protein, but DNA itself is too thin to see without a special type of electron microscope.

To get DNA from old bones, you scrape out some of the bone marrow and soak it in clean water. Then you mix some chemicals in that makes it break free from other crud that might be there. Then you have bits of DNA floating in the water (which you can’t see).

Once you have a bit of DNA, you can make copies of it. All cells have enzymes that can make copies of DNA, and you can now buy those from chemical suppliers. So, you use enzymes to make many copies.

Then, you “sequence” the DNA. It’s a chain of pearls with different colored pearls and there’s all sorts of ways of chemically figuring out what that sequence is, either by plucking one base at a time off, or adding one on. We “see” the base that’s plucked off using specially designed machines that can “read” the chemical signatures (there are many different ways).

You sequence lots of small pieces many times, so you have lots of sequence fragments. We represent their sequences as strings of the letters A, C, G, and T representing the four nucleotides forming the DNA chain (adenine, cytosine, guanine, and thymine). Then, you use computers to line up the fragments (which overlap each other) and stitch them together like a puzzle to reconstruct the larger original sequence. We can even recognize if the sequences come from contamination like bacteria.

Given the sequence, we can identify diseases, traits, compare it to different people groups to identify ancestry, link it to descendants, detect many diseases, etc.