Track 16

Unit 11

biology

DNA testing

Pages 106 and 107

Listen for main ideas and listen for details.

Hello, today I’d like us to concentrate on DNA. will focus on DNA testing and specifically on DNA testing of people, before I explain how it’s done. I want to review a bit from the reading.

That you’ll recall that cells comprise every part of our body are DNA is in every cell.

DNA contains genetic information like eye color, hair color, height, and many other traits passed down from a mother and a father to their child.

So, each of us has our own DNA our own combination of genetic information from our parents.

For example, a brother and a sister may end up with the same color of eyes and hair. However, other genetic information received from the parents will be different, which is why they look different.

For example, maybe the brother is short like the mother and the sister is tall like the father keep in mind that DNA is in every cell in the body and that all of these cells contain the same genetic information.

Now, let’s look at how DNA testing is used to identify people, scientists create a DNA profile also called a DNA fingerprint. To do this, they need DNA from the person, they take samples from different parts of the body like hair, blood, skin, fingernails and body fluids.

Next, they extract the DNA from the cells in the samples, then they read the DNA with the computer.

They use the data to create the DNA fingerprint statistically is very unlikely that any two people will have identical fingerprints.

Now let’s ask how is DNA testing used. Well, there are many ways. For example, to identify an unknown accident victim or to find out who the father of the child is not.

Here’s an interesting one. In 1999 scientist used DNA testing to prove that the son of the French King Louis XVI and Marie Antoinette.

In fact, died in prison, he didn’t escape as some people had believed DNA testing identified the son’s body.

People have been arguing about this more than two centuries. Another use of DNA testing is by police to solve crimes.

For example, say there’s a murder. The police have a suspect they think did it. In the crime lab scientists use DNA samples from the suspect and DNA samples from the evidence of the crime scene.

Then they design what’s called probes when the probes are put in with the DNA samples from the suspect and the DNA samples from the evidence.

The probes show the two sets of samples match. DNA identification is very effective, but not 100% foolproof.

For example, suppose the only evidence at the crime scene is blood from the suspect. If there’s a match between a sample of the crime scene blood in the suspect’s blood.

This will help the police. However, a single match from just blood. In this case isn’t very strong evidence.

In contrast, let’s say the crime lab has four samples from the crime scene and four samples from the suspect, hair blood, fingernails, and skin samples.

They design for probes, one for each sample and they get four matches bingo. The police can now feel more confident that they have the right suspect why?

Remember I said, DNA is in every cell in our body and each cell contains all of our unique genetic information.

Now, let’s turn to how DNA testing is used in the medical field here. Let’s consider how genetics is being used to diagnose diseases. With diseases most DNA tests are given for one of two reasons either to find out if someone has a certain disease or to see if the person is at risk for developing it.

Researchers have found more than 6000 genetic disorders a genetic disorder means something isn’t normal in the person’s genes.

A mutation, a change in one gene can cause a disease and a DNA test can show if someone has a mutation in a gene that puts them at risk of the disease.

Notice I’m not saying that a change in one gene will cause a disease, only that the risk is higher.

We’re learning more and more every day about genetic diseases. For example, it now appears that the disease Alzheimer’s which damages memory in older people is linked to our genes.

So, we have to ask one of the pros and cons of DNA testing in medicine. On the positive side testing might save lives if a doctor can diagnose the disease in its early stages, the patient can get treated earlier, or if a couple wants to have a baby.

They can use DNA testing to find out beforehand if any risks for problems or diseases exist on the negative side there’s the issue of fairness.

What happens if DNA testing reveals that we have a genetic disorder that could cause a disease and that information becomes known.

This brings us to some concerns about privacy a DNA profile contains a lot of personal information, so I’d like you to think about the following questions.

1) Who should own the DNA fingerprint once it’s made?

2) Who should have access to it?

3) How should genetic information be used and for would you want people, especially people who don’t know to have access to your DNA fingerprint. These are some of the ethical questions we face about how to use the scientific knowledge we have.

So, please give these questions some thought. As you review the lecture. That’s all for now.