Health
Health is defined by many as the sensation of well being, of feeling “sound in body and mind”. For others, health is merely the absence of disease. Each of these definitions is essentially correct as one’s health depends on the functioning of an array of chemical reactions, cellular processes, and biochemical interactions throughout the body. If all of these major bodily systems are functioning within a narrow set of parameters, homeostasis is maintained and we “feel healthy”. Homeostasis is the state in which bodily systems remain within a narrow set of parameters that are maintained through a complex series of negative and positive feedback loops. A variety of chemical reactions, organ systems, and biochemical processes maintain body temperature, pH range, calcium, glucose, phosphate levels, and water balance in our body. Major systems such as the nervous, endocrine, lymphatic and urinary systems maintain other critical processes within necessary values.
Bodily systems maintains homeostasis through the regulation of these various physiological and chemical processes while at the cellular – genetic level the orderly process of cell division through mitosis provides the mechanism for precise cell proliferation, processes in other cellular organelles support the body’s metabolic needs; while the orderly translation / transcription of DNA facilitates the synthesis of the proteins needed for life.
DNA Replication and Protein Synthesis
DNA encodes an organism’s genetic makeup (the genome). DNA is a double stranded helical molecule consisting of a ribose sugar, a phosphate backbone and four nitrogenous bases: (Adenine, Guanine, Cysteine, and Thymine). The strands are complementary to each other: which means that base pairs are held together by hydrogen bonds in the following order: Guanine – Cytosine, Adenine –Thymine: G-C and A-T). The sequence of base pairs encodes the information necessary to synthesize proteins used throughout the body. When a particular protein sequence is needed, the DNA molecule opens and the necessary sequence of bases is transcribed onto an RNA template. There is a slight variation in base pairing rules as there is no Thymine in RNA; thus A pairs with U in the RNA template. Once transcription is completed the DNA molecule closes and the RNA template moves to the Endoplasmic reticulum where ribosome translate the segment of RNA into a sequence of amino acids. The ribosome read the template in sets of three: as each trio of bases corresponds to a given amino acid. Once completed, the chain of amino acids will fold into a characteristic shape of the protein. Serious diseases and disorders can result if the sequence of base pairs is altered. Insertion or deletion of a base, a gene, or a chromosome lead to frame shifts in the RNA template that result in the synthesis of abnormal or defective proteins.
Alteration of DNA (or RNA) sequences is a mechanism that many pathogens use to alter their genetic characteristics. Such alterations allow some to evade immune responses, become resistant to medications, or continually evolve thus making it impossible to create a vaccine.
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