Deoxyribonucleic acid duplication

DNA (deoxyribonucleic acid) is well known as the molecule that bears all of the genetic information necessary to construct and operate a living organism. The cell nuclei of all eucaryotic organisms contain DNA and each cell contains all the genetic code needed to assemble the entire organism - a remarkable duplication of information. The amount of information involved requires the individual DNA... 

Deoxyribonucleic acid (DNA) replication The process by which DNA is dnplicated in the cell. This process takes place during the S-phase of the cell cycle. DNA is duplicated in a semiconservative manner that is, each new DNA donble-strand contains one of the original strands (parent strands) and one of the newly synthesized strands (daughter strands). 

A few years ago it was discovered that some diseases are molecular diseases, diseases of protein molecules. A gene, a molecule of deoxyribonucleic acid, may be damaged by coanic radiation or some other mutagenic agent in such a way that a few atoms are out of place. This gene dien duplicates itself in its new, mutated, form. Moreover, when it... 

The nucleus is responsible for the direction of the metabolic activity of the cell. The key to this activity lies in the chromosomes, threadlike bodies containing a nucleic acid, deoxyribonucleic acid (DNA), and, more specifically, in the genes which are incorporated in the chromosomes. The great majority of human cells, the somatic cells, contain 23 pairs of chromosomes. The only exceptions are the gametes (sperm cells and ova), involved in reproduction, which contain only half this number. The combination of a sperm and ovum in the fertilization process produces a new cell (the zygote) with the required 23 pairs of chromosomes, which forms the basis for the new individual. Further development takes place by mitosis, or cell division, a process in which each chromosome duplicates itself prior to the cell splitting into two new cells, each of which emerges with an identical set of 23 chromosome pairs. 

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