Answer 1:
DNA is basically what makes live possible. It is the set of recipes for making an individual, whether that individual is a person, a mushroom, a pine tree, or a bacteria. We call the recipes genes. They are arranged on chromosomes.
We all start off as one cell--a fertilized egg. That cell keeps on dividing as we develop. Cells become more and more specialized, but they all keep the entire set of DNA. They only use the part they need to do their jobs. The only cells in your body that do not have the complete set of DNA are mature red blood cells and gametes.
Gametes are the egg cells that females make and the sperm cells that males make. If you take a cell from your skin, kidney, or anywhere else in your body (except the ones I just mentioned), you would find the same DNA.
DNA has to be copied before cells can divide. Sometimes mistakes are made during the copying. These are called mutations. Some mutation happens even in the best of circumstances, but some things can speed up mutation. There are some chemicals that can cause mutation. High-energy waves, like X-rays and the UV rays of sunlight can also cause mutations. That's why medical workers are very careful with X-ray machines and why we should be careful about getting too much sun. Being outside is great, but it's important to use sunscreen, especially if your skin is light. I don't know of any way to strengthen DNA.
The only DNA that gets passed from one generation to the next is the DNA in gametes.
Mutation in an egg or sperm cell can get passed to the next generation. Mutations in any other cell (skin, organs, muscles, etc.) will not get passed to the next generation.
By looking at one individual's DNA, you can tell something about other individuals. For example, we get half our DNA from our mom and half from our dad. If you have a child, they will get half their DNA from you. The closer a relative is, the more DNA you will share with them.
There are a number of different tests that can be done with DNA. Law enforcement might test things like blood at a crime scene to identify who the blood came from. Doctors might test for particular genes to find out whether a person has inherited a certain disease. They might test cancer cells to figure out what mutation caused the cancer. This helps them identify the best treatment. People also send their DNA to companies in order to find out about their ancestors and other relatives.
There is an exciting new technology for fixing DNA. It's called CRISPR cas-9. It's pretty complicated, but it allows doctors to inject a "corrected" gene into an area where cells can't do their job because of a mutation. I predict that you will see this being used more and more in your lifetime.
DNA does change over time due to mutations and natural selection. Mutations aren't all bad. Whether they are good, bad, or neutral may on the environment. If an individual passes on a mutation that gives an advantage to some of their offspring, those offspring are more likely to survive and reproduce. The mutation will become more common. Evolution means a change in the frequency of a gene over time.
This site shows a couple of different ways that people draw DNA: . We really can't see it at this level, our microscopes are not powerful enough.
If you could study one thing about DNA, what would it be?
Click Here to return to the search form.
| 
