Our bodies are constructed of million of cells, living, dying, changing all the time. Some cells live for a few months, others for years. The female egg cells, for example, can live fro fortyfive to fifty years. All these body cells contain chromosomes, which are long threadlike structures that operate in pairs and look something like two arms. The genes, containing the DNA code that imprints physical characteristics, such as the color of our hair and eyes, our blood type, and even our personalities, are in hundreds of miniscule dots on the chromosomes.
Unlike the genes, the chromosomes are distinguishable under the microscope. Back in 1880s, it was discovered that these thredlike structures can absorb a special kind of dye and so become visible. (Their name derives from the Greek words, chroma, meaning color, and soma, meaning body.) Although we now use highly sophisticated techniques, the basis remains the same. The chromosomes are stained and investigated under magnification. The pairs are assessed for the right number, the proper structure, and the possible of damage to individual ones.
Each of us has 46 chromosomes in every cell. Twenty-three of your chromosomes were inherited from your mother and the other 23from your father, including one sex chromosome from each parent. If you inherited 1 x and 1 y chromosome, you became male; two x’s and you became female.
So each individual has 22 pairs, known as autosomes, plus its two sex chromosomes (the x’s or y’s) adding up to the requisite 46. as mentioned previously, during the process of meiosis, which occurs just before the moment of conception, each cell has only 22 autosomes plus 1 sex chromosome, so that when the sperm and egg lock sides, they will create one complete whole. When romantics write of falling in love, meaning you have found the “other half” to your whole, they are indeed quite right!
Random selection decides which two cells, with particular genes attached to the chromosomes, will meet and mate, which is also why we are all so uniquely different. Genetic diseases therefore, are set in motion from that moment of fertilization when the different genes meet and match.
The other important process of cell division is mitosis, which takes place within the twelve to twenty-four hours after the egg and sperm have met. This process marks the beginning of rampant cell multiplication as the conceptus begins to grow. At this stage some chromosomes can be lost or broken, or if there is an extra one present, it may lead to deformities. These kinds of abnormalities are usually miscarried early, and as I have emphasized before, they usually do not occur again, depending on the exact chromosomal configuration.
