Explain it to me like I'm 50

Explain it to me like I'm 50...
This is what my forensics teach asked us to do: to explain DNA analysis to a 50 year old with a 5th grade education.
It was a good time for the question. All this labor day weekend, while on our anniversary trip, I talked through running gels with my husband.
He is not 50 but he is an IT guy not a biologist.
This is how I answered.

Imagine that you are standing on an unpaved road near a beach. The road is mostly sand and seashells.

Imagine you are standing on an unpaved road near a quarry. The road is mostly gavel and clay.

Imagine you are standing on an unpaved road in the mountings. The road is mostly earth and sticks with a few rocks in it.

  These roads although they serve the same purpose and may even be the same size are very different. They each contain particle elements that are quite distinct from each other. They are all influenced by their environments, by the traffic they experience and by the weather they are exposed to.

 These elements represent the DNA of the roads.

 Each person is made up of small parts that are as unique as the road components above.

DNA analysis is the process by which these parts are identified and presented.

 The process of analysis takes place using gel electrophoresis.

The gel part is very much like clear Jello.

 It looks like a flat wallet sized and shaped ‘plate’. Each gel plate has some very small wells in it, near the top in the middle and near the bottom. DNA samples with some dye in them, to make them more visible, are put into the wells.

 The electrophoresis part is a small container, just big enough to hold the plate and filled with buffer (basically salt water). The container has terminals just like a car battery. When the DNA loaded gel is in the container. The terminals are hooked up and electricity is applied.

 The electric current in the buffer is enough to push the DNA from its wells through the gel. The current is mild and only going in one direction. The bigger heavy proteins (like the rocks and shells above) move very slowly. The smaller and lighter proteins (like the sand or clay) move more quickly. It is easier for small things to move through Jello than it is for large things to move through Jello.

 After about 20 minutes the electricity is turned off and the gel is taken out to be photographed and/or analyzed.

 Each person has a different amount of big and small bits to their DNA, just as each road has different amounts of big and small bit.

 Each persons gel will necessarily display their unique make up of big and small bits and it is the job of scientist analyzing their DNA to produce a picture (literally) of what that looks like.

 I am attaching a picture of some gel plates that I made last week so you can see what they look like. The white things are molds for the wells as these gels are not set yet.

 Also NOAA has a nice picture of the DNA sample being loaded into a gel here.

http://oceanexplorer.noaa.gov/explorations/03bio/background/molecular/media/gel_plate.html

I should have said something about amplification.

I should have said something about sample size and condition and source.

I should have said something about purification too but overall I loved the question.

I was told in a math class once that if I couldn't explain something clearly that I really didn't understand it well enough.

I think that is not true for some people.

It might very well be true for me.

I am going to try to apply the question or at least the principle of the question to what I am learning here.

That should assure my assessment of my own comprehension at least a bit.