How do the DNA modules tell the cell what to do?


closed as too broad by jonsca, jarlemag, kmm Apr 30 '14 at 0:56

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    $\begingroup$ Since this is pretty broad, have you tried looking it up in the Wikipedia and then ask some more specific questions? This stuff fills a few pages in biology books and probably no one wants to write this down here... $\endgroup$ – Chris Apr 29 '14 at 20:27

This question is too broad (and also a bit poorly defined). I will try to give few concepts to help you in your exploration of wikipedia articles. If then you have more specific question, we'll be delighted to help you answering them.

In very short...

The genetic information contained in DNA in coded through codons, which are series of three base pairs, there are 4 different base pairs, namely, A,T,C,G. Therefore, there are $4^4 = 64$ but these 64 codons codes for only 20 amino acids (in most species). By analogy you may consider a base pair as a letter, a codon as a word (all words are made of 3 letters) and genes are sentences. But many words are synonymous. The genetic code is said to be redundant.

DNA is a double stranded molecule, which splits in two around a coding region so that a RNA molecule can be created by copying the DNA template. This process is called transcription. This RNA is called pre mRNA. It is then spliced to become a mRNA (messenger RNA). The mRNA exit the nucleus. Two rRNA (ribosomial) RNA (which forms the so called ribosome) attach to the mRNA and tRNA (transfer RNA) will recognize the RNA sequence and paste amino-acids the ones to the others according to RNA sequence. This process is called translation. The molecule that is constructed is a polypetpide (a protein).

The quantity of proteins that are produced can be regulated by various mechanisms at different "moments": pre-transcription, pre-translation, post-translation.

  • $\begingroup$ Great answer Remi. Along these lines, I wanted to impart an important concept to understand as you read. Most proteins become either enzymes or structural components in the body. The key to conceptualizing the DNA-->RNA-->protein process is this: shape determines function. A strand of DNA is a template for which the Amino Acid (AA) subunits will be strung together in a chain. That chain will fold into a complex shape. The shape is determined by the interactions between the different amino acids. Each AA has unique effects, causing the chain to twist, bend, loop, link together, etc. $\endgroup$ – DoctorWhom Apr 30 '14 at 7:26
  • $\begingroup$ Once the AA chain is done bending, it's a shape that is pretty much unique to that protein. For enzymes: the shape of the enzyme determines what it can do, how it interacts with molecules, and where it can go in the body. Shape is everything. For structural components, shape is everything too. Think of an engine - the shape of each component is critical to its ability to function. Because the order of Amino Acids in the chain causes it to form a specific shape, that is why the DNA sequence is a template for the protein's shape - and ultimately, its function. $\endgroup$ – DoctorWhom Apr 30 '14 at 7:30

I agree with Chris that this is way too broad a question. But if you want a very broad answer...

DNA is a long molecule consisting of a sequence of 4 different subunits. The sequence of those subunits determines the shape of the DNA, and its shape determined how it interacts with other molecules, based on their shapes.

Computer code doesn't work like that at all, so I think you need to really strongly question your premise that knowing anything about computers is going to tell you much about biology.


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