Scientists Discover Secret Of Heredity

Press, Volume CI, Issue 29994, 1 December 1962, Page 8

Scientists Discover Secret Of Heredity

[By a Science Correspondent]

LONDON, November 20. rpHE human body is made up of some billions of cells, each one too small to be seen by the naked eye. They are differentiated into fantastically different structures to perform different functions in different parts of the body, hut at heart every cell in any one person is much the same. It is a complex chemical machine with a controlling centre, the nucleus.

Within this controlling centre every cell carries chromosomes. What they are like while the ceU is performing its job we do not yet know, but when a cell divides in two in the process of growth, these arbiters assume a shape which is common to every cell, appearing as 46 tiny threads. These threads not only control the day-to-day organisation of the cell, its breathing, feeding and replacing of worn-out components, but they also account for the subtle differences which exist between, say, two sons of different families.

Quite recently scientists have begun to discover the letters of the alphabet in which the instructions for a child's heredity are written. They have found that these letters are represented by the different ways in which a few chemical groupings are arranged down the length of molecules. shaped like spiral springs, which make up the chromosomes. Dr. James Watson and Dr. Francis Crick, of the Cavendish Unit of Molecular Biology at the University of Cambridge, were the first to work out the structure of these spiral molecules, which are made of the now famous substance deoxyribonucleic acid—DNA. A few different chemical groupings are arranged in an irregular sequ-

ence down the length of each spiral strand of DNA, and it is the order in which these are arranged which seems to determine the particular instruction which that particular piece of DNA gives to the developing cell. The chemical groupings stick out sideways from the chromosome like the ragged edges of keys, looking for locks, and just as a lock fits a key, so specially-shaped chemicals grow round these specially-shaped keys, then travel out into the cell, carrying by their structure the message of heredity that was laid down in the chromosomes.