"junk DNA" a useful term or not?

An attempt to repsond to Faiths questions in Message 96 On junk DNA: It's the same basic stuff as normal DNA (chains of adenine, thymine, cytosine and guanine, the four bases). IIRC pure DNA's a sort of white slime, although you need a lot to be visible. If it is really junk, than that's right, although a lot of sequences get labled as junk just because we don't know what they do do. Pseudogenes are the remains of genes that once did something useful, but don't any more. If a gene is no longer needed (because it codes for an emzyne that is no longer needed, for instance, or simply got duplicated and is a spare) it may mutate into somthing that looks like a gene, but is gibberish. Definatly junk... Introns act a bit like the spaces in a sentence: The really useful information is in the Exons (words), but if you shoved them all together in wouldn't be very readable. They may also have some functions in replicating/checking the rest of the code, but that's a bit deep for me... I hope you mean for Introns... Try this... I think most evo's would agree that for a lot of it, the function is just unknown. I think the Human Genome Project succesfully identified the code sequences for every protien in the body. It was the other 99% that was a problem.I await one of our resident biologists to tell me this is all completely wrong...

A quick thanks to everyone for for the corrections & clarifications...

I stumbled across this earlier, and reminded me of Faiths "What does it look like?" question. I haven't tried it myself yet.You will need:
Water
Salt
Washing-up liquid
Some strong booze (ie Gin)
Two glassesMethod:
Put the booze in the freezer until it's ice cold.
Put a teaspoon of washing-up liquid in one of the glasses, and add 3 teaspoons of water.
Mix up some salt water in the other glass.
Rinse your mouth with the salt water for 30 seconds. This will collect some cells from your mouth.
Spit it into the washing-up liquid glass and stir fow a few minutes. The detergent will break up the cell walls and release the DNA.
CAREFULLY pour a couple of teaspoons of gin down the side of the glass: It should form a seperate layer on top of the mix.
After a few minutes, you should see white clumps appear in the gin. That's your DNA.(Copied from New Scientist's "101 things to do before you die" book. Sadly, all I have in at the moment is Guinness, so it will have to wait 'til tommorow...)Enjoy...This message has been edited by Dead Parrot, 05-23-2005 07:47 PM