D
Deficiency is described as a condition arising from a lack of one or more of the essential nutrients. This occurs most often because of a primary *- dietary inadequacy, or a secondary *- conditional inadequacy. The condition is progressive if untreated, eventually leading to a depletion of body nutrient reserves. Biochemical changes occur in selected tissues or in the body as a whole, eventually resulting in functional body changes. If allowed to continue, anatomical changes develop, as well as such gross clinical signs and symptoms as skin lesions, cracked lips, clubbed fingers, etc.
Thus, the development of diseases occurs in five stages: 1) nutritional inadequacy, 2) tissue depletion, 3) biochemical changes, 4) functional changes, and 5) anatomical changes.
*Primary is the failure to ingest adequate amounts of essential nutrients to meet the needs of the body. This may be as a result of poor eating habits, poverty, ignorance, lack of food, or an excess consumption of highly refined foods.
*Secondary is called conditional because it can result as a failure to absorb or utilize an essential nutritional factor.
These conditions can be placed within 6 categories: 1) interference with ingestion, 2) interference with absorption, 3) interference with utilization, 4) increased nutrient requirements, and 5) increased nutritional destruction and 6) increased nutritional excretion.
DNA (deoxyribonucleic acid) was discovered by Watson and Crick in 1953. It is a single molecule, found in the chromosomes within the nucleus of a cell, consisting of strands held together by hydrogen bonding between nitrogenous bases and its sugar, deoxyribose.
It is found in the nuclei of cells as part of the chromosome structure and consists of phosphoric acid, purines (adenine and guanine), pyrimidines (cytosine and thymine), and the sugar deoxyribose. The structure is envisioned as a double helix in which the purine and pyrimidine bases are inside the helix and the sugar and phosphate backbone are outside the helix. The chains are held together by hydrogen bonding.
This information storage system is known as the genetic code and is the root that controls all of life's processes. The genetic code is called a triplet code because of a sequence of three nitrogenous bases that can specify the identity of a single amino acid. Each gene consists of all the triplets needed to produce a specific protein. Because one triplet controls a single amino acid, the number of triplets, as well as the size of the gene, varies depending on the length of the protein that will be produced. Each gene also contains special segments responsible for regulating its own activity. In effect, these triplets are constantly relaying messages saying to read (or not to read) this message or the message starts (or ends) here.
Other than identical twins, the probability of two people having the same DNA patterns is less than one in 9 billion. DNA identification can be made from skin scrapings, blood, semen, hair, or other tissue sources. Each molecule of DNA contains thousands of genes and, therefore, holds the information required to synthesize thousands of proteins. Before a specific gene can be activated, enzymes must temporarily break the weak bonds between nitrogenous bases and detach it from the associated histones. The process of protein synthesis is divided into transcription (the production of RNA from a single strand of DNA) and translation (the assembling of a protein by ribosomes, using the information carried by the RNA molecule). Transcription takes place within the nucleus, and translation occurs in the cytoplasm.
