GHOST WRITING

HOW YOUR PARENTS BESTOWED THEIR INHERITANCE

In keeping with the classical approach, the next obvious question now was ‘how’ exactly are the traits or physical features that define an organism, inherited or passed on. It was a well‐known fact that life propagated (or continued) itself, with parents creating offspring that bore an uncanny resemblance to themselves. So too it was obvious that there were ‘some types of information’ being passed on from parents to offspring and done so in some type of mechanism. You can imagine how you’re not an exact replica of either your father or mother and might have heard comments like, “you have your father’s chin” or “you have your mother’s smile.”

Gregor Mendel, the father of genetics, did some basic experiments on pea plants to determine how traits are passed on from one generation to the next – and led to Mendel’s Laws of Inheritance. It was a stunning explanation – a mathematical one at that – to why traits from two parents are passed on without any sort of ‘blending,’ the reigning concept till then where an offspring was an ‘average’ of its parents. Mendel’s observations with pea plants saw that certain traits were dominant and passed on with greater frequency, which others were recessive and were expressed with greater rarity.

Experiment:

Imagine two parents, each carrying two versions (called alleles) of the same gene – one dominant and one recessive. The laws of inheritance state that each child of the parents will receive one version from each parent. At this point, it is an exercise in probability. So let’s imagine the parents have four children – Child 1 has 1 dominant allele from Father & 1 dominant allele from Mother; Child 2 has 1 dominant allele from Father & 1 recessive allele from Mother; Child 3 has 1 recessive allele from Father & 1 dominant allele from Mother; and Child 4 has 1 recessive allele from Father & 1 recessive allele from Mother.

Children 1, 2, and 3 will invariably only display the dominant trait, even though two of them carry the recessive trait as well. Child 4, however, will only display the recessive trait since he/she did not inherit the dominant one at all.

Mendel’s Laws of Inheritance: Alternative versions of genes account for variations in inherited characteristics; for each characteristic, an organism inherits two alleles – one from each parents; the two alleles for each characteristic segregate during reproduction; and the inheritance pattern of

This was a triumph for classical biology since here was another ‘beautifully’ simple explanation for how offspring were entirely a product of their parents. One trait from father, one trait from mother – for any number of traits like eye color, size, intelligence, strength, and so on, was the way life continued the unbroken chain of reproduction that started millions of years ago. The connection was made and now biologists could examine the exact biological mechanism with which the parents passed on their traits.

Mendel’s discovery was not immediately accepted until another scientist, Thomas Hunt Morgan, who was responsible for studying the physiological properties of genetic inheritance, proved the laws of Mendelian inheritance in fruit flies and demonstrated that genes are carried on chromosomes inside each cell. Then, James Watson and Francis Crick, drawing upon the work of Rosalind Franklin, formulated the first accurate model of DNA – deoxyribonucleic acid – the chemical that contains the genetic instructions for an organism’s development and functioning.

(Continued in the Book)