Expert: Walter Hintz - 2/24/2010

Question
Hello,

I am trying to make a model of a brain in computer and I just thought that the way DNA works might inspire me somehow. But I don't know biology or genetic.

Now, I know that gene are molecules of A-T or G-C pairs. The length of pairs can be long or short. And each length (is it chromosome?) is designed for specific function. For example, a chromosome controls how a leave grow or how a fruit's skin looks. I have seen letters on leaves or fruit skin by genetic modification.

Could you tell me how these pair do what they do? How the system of A-T G-C code works?

Thanks you

Answer
Hi Frans
There are some problems with definitions here. Lets go there first
A gene is a packet of DNA
Chromosomes are made up of genes
DNA is a nucleic acid made up of a nitrogen compound, a 5 carbon sugar and phosphate molecules
DNA consists of a double strand of 4 different nucleotides, Adenine,Thymine,Cytosine,and Guanine(A,T,G,C) The strand are connected A to T and G to C

DNA not only replicates itself but guides the formation of RNA and RNA guides the synthesis of proteins. What type of protein is determined by the sequence of the nitrogen compounds. The code is the sequence and the sequence is established by the base pairing rule that A can only connect with T and C can only connect with G.
 For example you mentioned  fruit skin.
The color of an apple depends upon protein enzymes
 sequence AATCGGCTA could code for red skin
          ATTCGGCTT could code for yellow skin

Heredity is quite involved and I could only give you basics here