DNA Extraction

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DNA extraction refers to the process that scientists use to break down a piece of evidence, such as a piece of hair or a drop of blood, in order to determine the individual's DNA, which is unique to each person. Understand the process of DNA extraction with information from a biology teacher in this free video on science.

Part of the Video Series: DNA Structure & Testing
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Video Transcript

Have you ever watched one of those old detective movies and watch them dust for fingerprints? They consider that to be the best evidence they could come by. Well now forward to the modern day detective shows like CSI and what are they after this time? A human hair. Well the prize that they're actually looking for lies inside that hair and that prize is DNA. Hi I'm Janice Crenetti. I've been teaching science and biology in high school for over 20 years and I'm here to talk to you today about how DNA is actually extracted. Well DNA is the genetic material, it's the blueprints that makes us, us. And so let's say that a scientist or a detective wants to prove that someone is actually guilty of a crime. They can create something that's called a DNA fingerprint that's going to be unique from one person to the next. Well to create that DNA fingerprint, they've got to get after the DNA which means it has to be extracted. You see a DNA molecule like this actually lies inside the nucleus of a cell. So they have to get into the cell and then into the nucleus of the cell to get after this material. There's a several stage process that they go through. First of all, they're going to have to breakup the cell wall if it's a plant cell or get into the cell membrane. So to breakup a cell wall, they might use a pulverizing implement like let's say a common blender. Then they're going to use a soap material, either regular household detergent to dissolve the cell membrane that they need to get inside the cell and then inside the nucleus. Once they're in there, they're going to apply some alcohol which is going to cause the DNA molecules to clump together and precipitate, that means fall to the bottom of the container. Well now they've got the actual DNA. They can take that, if they need to, they can replicate it to produce more and they can take that DNA and put into a fingerprint. They can run that DNA and see whether this person's DNA matches for instance a hair sample that's been collected at the scene of the crime. It's a lot to go through, but DNA is absolutely the best way to tell that you've got your man. I'm Janice Crenetti and this is DNA extraction.


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