How to explain DNA to 8 year olds...

[suppleasthewind]

We watched Nova last night and the boys were really into it. I kept struggling to explain DNA to them and I guess I don't really understand it myself.

 

Can anyone recommend resources?

[Catherine]

Any good science encyclopedia written for grammar or logic stage should have some info.

 

Basically, DNA is a long chain of molecules. Each molecule, link, in the chain, is one of four varieties, A,T,G, or C. But it is like a zipper, with actually two chains linked together in the middle: A's link to T's, G's to C's. RNA can unzip this double chain and generate another chain by matching to the DNA links. This RNA chain then goes into a different part of the cell where protein "links" (there are 22, called amino acids) match to the RNA links, forming a long chain protein molecule. In this way, the "code" for each protein is stored in the sequence of DNA base pairs, and the amount of protein created is controlled by the rate of DNA replication.

 

Clear as mud?

[Bang!Zoom!]

Here's a Bill Nye video:

 

[suppleasthewind]

I love Bill Nye! I will show that to the boys.

 

Catherine, I was wondering if every cell in your body has the same DNA, but your tissue cells only express tissue info, and muscle cells only express muscle info.

[Stuart]

Check studyjams too. They are great science videos. There is one on heredity that might be good. I haven't watched that one yet. My 8 year old loves them.

[ChrissySC]

DNA Educational Center

[Momling]

Brainpop has a nice little video on it... and it's free! http://www.brainpop.com/science/cellularlifeandgenetics/dna/

[Catherine]

But yes, as you say, the DNA in different tissues has different rates and sites of replication. The "turning on" and "turning off" of DNA expression is one hot area of current scientific inquiry. Disordered control of "gene expression" (activation of DNA) is thought to play a role in autoimmune disease and cancer.

[NittanyJen]

You got a good response already; if you child is at all at sea with it and you want to oversimplify a bit:

 

DNA is like the instruction book that tells the cells in your body how to take the proteins and molecules it has available, and tells them how and when to assemble and use them, kind of like the instruction book that comes with your lego kits. In different cells, chemical signals are sent to tell the DNA which instructions to follow at different times so that immune cells carry out immune responses and bone cells can become big strong bones or create red blood cells, just like in a big Lego kit you might have different sets of instructions to build different types of vehicles from the same kit.

 

By the way, there is a Science Wiz kit (about $20) for DNA that lets you build a small model of a DNA helix, extract DNA from a piece of fruit in a simple experiment (no microscope needed; you can see the extracted DNA salts with the naked eye as a long white string), carry out a karyotype (match up the numbered chromosomes and the XX, XY, or XXY chromosomes to match your child; sorry, I don't believe the kit has XXX or XYY or other SCA variations, or trisomy 15 or 21).

 

Jen