Once scientists understood how DNA is put together and how it's code works, research began to focus on methods for analyzing DNA. Our current methods of DNA analysis allow us to modify plant and animal DNA to create GMOs. These same techniques allow scientists to find genetic disorders and may lead to cures for diseases.

One very useful form of DNA analysis, called restriction fragment length polymorphism (RFLP), can be used to determine paternity. That means the in cases where an animal's father is unknown, we can compare the DNA of all possible fathers and determine which is the offspring's father. This begins by collecting DNA samples for the mother, offspring, and all possible fathers. In animals, DNA can be extracted from cells found in blood or saliva. Hair follicles (the cells at the base of the hair shaft) can also be used. The hair itself doesn't actually contain any DNA.
Once the DNA is extracted, it is cut with special enzymes, called restriction enzymes. These enzymes cut DNA at specific sequences, producing fragments of different sizes. Since each organism got its unique genetic code from its parents, its DNA will cut in the same places as its mother and father's DNA. Since half of the DNA was inherited from each parent, half of an offspring's DNA fragments will be the same size as its mothers, and half will be the same size as its father's.
Unfortunately, DNA fragments when cut are too hard to see. In order to spread out the fragments, another technique, gel electrophoresis is used. We'll go into detail about how this works in the next lesson, but when DNA is loaded into a block of gel and an electric current is applied, the DNA fragments spread out so that each fragment is visible. The pattern of DNA fragments that results is called a DNA fingerprint because it is unique to the person, just like a fingerprint. Because each DNA sample is loaded into the gel next to the others, it's easy to compare them. You can see which fragments in an offspring organism match those of the mother. The rest of the offspring's fragments will exactly match those of the father. The picture on this slide shows what DNA fragments in a gel look like.
Similar analysis can be done with plants after obtaining cell tissue samples from different plant parts.

Sometimes, we want to analyze DNA, but we don't have a large enough sample to cut and run on a gel for that analysis. This is often the case when we find the remains of an organism, like a mummy or a wooly mammoth buried in ice. There is a procedure called polymerase chain reaction, or PCR, that will allow us to mass-produce copies of DNA. This is called DNA sample amplification and involves a machine that can rapidly cycle through heat and cold temperatures, which stimulates fast replication. Once the sample is amplified, it can be analyzed.
In addition to PCR, another advanced analysis technique, amniocentesis has lots of agriscience applications. During this process, cells from a mammal before it is born can be removed from the mother's uterus. DNA from these cells can then be sequenced to determine if the baby has any genetic disorders. In recent years, this has been used extensively in high-expense breeding operations, like race-horse breeding stables.

This is just the tip of the iceberg as far as DNA analysis is concerned. Scientists use a technique called sequencing to read the code on the DNA molecule to find mutations and even make maps of where certain genes are located on chromosomes!
In the next lesson, you'll take a closer look at some of these DNA analysis techniques and even get to try them for yourself.