may even have "holes" in it - empty spaces into which other smaller molecules can wander like ships entering a harbor bounded on two sides by moun- tains. Depending on its particular shape it can bind and hold other molecules of different kinds and by binding them in specific posi- tions those other two molecules are allowed to "react" with each other either to combine to make a new type of molecule or to transfer small portions of one of them to the other, to combine with water or other small mole- cules available in the vicinity. When these changes have occur- red the modified molecules ei- ther don't fit as well into the spaces as the original ones did or their energetic characteristics have changed so that the large protein molecule can no longer bind them or for other reasons. In any case they are released into the surrounding medium and the protein is back to its original state and ready to bind some more of the same kind of mole- cules. This is a process called ca- talysis in which the protein helps other molecules to react without itself being changed in the pro- cess. This is what metabolism is all about.

Now it needs to noted that the shape the protein chain folds up into determines what it can do as a catalyst but in turn that shape is determined by the specific kind and arrangement of the ami- no acids of which it is composed There are 20 different amino acids involved and proteins can contain thousands of such acids so it is easy to see that the num- ber of kinds of protein molecules possible is almost astronomical. So since this specificity is essent- ial to the function of the protein

it should be obvious that if some slight accident occured during the formation of the DNA chain that it would change the code for a given amino acid at one point in the chain so that when the DNA was synthesizing the pro- tein (thru a series of steps to complicated to go into here) that change in the DNA will also re- sult in a different amino acid being inserted into the protein chain during synthesis. If this oc- curs the protein may not be able to fold and twist itself into the shape it was supposed to attain and therefore it would not be able to bind and allow the same small molecules to react and thus it would'nt work correctly. It is the small changes in the DNA that are called mutations and they don't in and of themselves do anything except in turn to change the kind or order of ami- no acids going into the synthesis of a protein which in turn then cannot do what it is supposed to do. A protein that helps a reac- tion to take place is called an enzyme. Now enzymes are invol- ved in the conversion of starch and sugar into ethylalcohol in the fermentation process of mak- ing wine. When the right en- zymes are present, the wine con- tains the right percent of alcohol and various other substances that are formed during the fermenta- tions, one has good wine. But acetic acid is a very close relative of alcohol. If the protein which is the enzyme that ferments su- gar to alcolhol would have been synthesized from a mutated gene it might be that the shape such a modified protein assumed would be unable to bring about the for- mation of ethyl alcohol but would cause the formation of a- cetic acid instead. In the first

case you get wine, in the second case you get vinegar. Note that there is not "a gene for good wine" in the yeast plant. No gene by itself makes a complex finished product whether it be wine or red hair. All the gene does is to control the synthesis of a protein strand that winds up into a particular conformation which is capable of enzymatic action to bring about some spe- cific chemical reaction under some specific circumstances.

Let us consider hair color. We have blonde hair with no pig- ment, brown hair with some pig- ment, black hair with a lot of

pigment and red hair is a chemi- cal called Melanin. There will be a gene which makes an enzyme which controls the synthesis of Melanin under special conditions. Melanin doesn't just color hair. It is responsible for the "tan" you get on exposure to the sun. The conditions in the skin are such that when acted on by ultra vio- let light the enzyme which synthesizes melanin is activated and the pigment is produced and you get a "tan". The point is that caucasians are not born with a tan. The enzyme is there all the time but it becomes active only under certain conditions. Black people have an enzyme which works even in the womb so that black babies are born black. On the other hand there are people called albinos who have no pig- ment and cannot produce any and whose skin and hair is white and who get seriously burned by the ultra violet rays in sunlight because they have no ability to produce pigment to protect them They have to use arteficial sun screen chemicals to place a film between the skin and the sun to

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