Welcome to my blog, in which I'll attempt to explain how things work! As someone with a fairly broad field of interest, I intend to cover a large amount of subjects - from genetics and cycling, to ocean waves and selling cars. However, as a trained scientist I predict that I'll post a bit more about science-related stuff. My goal is to try and make complicated things a lot easier to understand.
So, without further ado:
Paternity testing
Every person has DNA in the cells of his or her body. Half of your DNA comes from your father, and the other half comes from your mother. Scientists have developed techniques to compare the DNA of a child with that of their parents.
In particular, small bits of DNA that we know are often different between individuals, are copied thousands of times so we can discriminate these important bits from unimportant DNA. These bits of DNA differ in size between different people, so scientists just need to separate the DNA bits (fragments) to compare their sizes. DNA is separated in a slab of gel which works like a series of sieves where the biggest DNA fragments get stuck towards the top, while smaller fragments move towards the bottom where they get stuck. Each person's DNA is analysed separately.
This is a gel being loaded with DNA. The DNA is suspended in a coloured dye before the fragments are separated. The DNA is separated with an electric current.
After the DNA fragments are separated, you can stain the DNA with a dye that is visible under UV light, and this will show you where the DNA fragments are in the gel. This is how it might look:
In column 1 there is a "ruler" that you can use to compare the size of DNA. Next to column 1 you can see DNA sizes. "bp" stands for "base pair", a unit in which DNA is measured. As you can see the largest fragments (23130 bp) are at the top, while the small fragments (564 bp) are at the bottom. Columns 2, 3, and 4 contain DNA samples from different sources.
Say we get DNA from Jane, her baby, and two men who claim to be the father. Who do you think is the father?
The baby shares one DNA fragment with Jane (second from the top). The baby also shares two DNA fragments with Man 2, but none with Man 1. Therefore Man 2 must be the baby's father!
This sort of technique is also used by scientists to identify contamination in foodstuffs (for example, if canned meat is contaminated with other meats that aren't supposed to be in the can), to identify plant and animal species, and to identify bacteria, viruses, and fungi - especially when they are causing disease.
So, without further ado:
Paternity testing
Every person has DNA in the cells of his or her body. Half of your DNA comes from your father, and the other half comes from your mother. Scientists have developed techniques to compare the DNA of a child with that of their parents.
In particular, small bits of DNA that we know are often different between individuals, are copied thousands of times so we can discriminate these important bits from unimportant DNA. These bits of DNA differ in size between different people, so scientists just need to separate the DNA bits (fragments) to compare their sizes. DNA is separated in a slab of gel which works like a series of sieves where the biggest DNA fragments get stuck towards the top, while smaller fragments move towards the bottom where they get stuck. Each person's DNA is analysed separately.
This is a gel being loaded with DNA. The DNA is suspended in a coloured dye before the fragments are separated. The DNA is separated with an electric current.
After the DNA fragments are separated, you can stain the DNA with a dye that is visible under UV light, and this will show you where the DNA fragments are in the gel. This is how it might look:
In column 1 there is a "ruler" that you can use to compare the size of DNA. Next to column 1 you can see DNA sizes. "bp" stands for "base pair", a unit in which DNA is measured. As you can see the largest fragments (23130 bp) are at the top, while the small fragments (564 bp) are at the bottom. Columns 2, 3, and 4 contain DNA samples from different sources.
Say we get DNA from Jane, her baby, and two men who claim to be the father. Who do you think is the father?
The baby shares one DNA fragment with Jane (second from the top). The baby also shares two DNA fragments with Man 2, but none with Man 1. Therefore Man 2 must be the baby's father!This sort of technique is also used by scientists to identify contamination in foodstuffs (for example, if canned meat is contaminated with other meats that aren't supposed to be in the can), to identify plant and animal species, and to identify bacteria, viruses, and fungi - especially when they are causing disease.
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