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After eliminating those four foods the asthma symptoms decreased so much Andrea was able to cut out one medication. Genes that may have health issues essay into Down syndrome include: These are all symptoms of an eating disorder. I understood the point. It proved a liberating stroke. This would not be difficult. In this case, health issues essay, two breaks occur in separate chromosomes, usually the 14th and 21st chromosomes.



A Brief History The formal story began in , when a physician named John Langdon Down published an essay in England in which he described a set of children with common features who were distinct from other children with mental retardation. Down was superintendent of an asylum for children with mental retardation in Surrey, England when he made the first distinction between children who were cretins later to be found to have hypothyroidism and what he referred to as "Mongoloids.

This ethnic insult came under fire in the early s from Asian genetic researchers, and the term was dropped from scientific use. In the first part of the twentieth century, there was much speculation of the cause of Down syndrome. The first people to speculate that it might be due to chromosomal abnormalities were Waardenburg and Bleyer in the s. Cases of Down syndrome due to translocation and mosaicism see definitions of these below were described over the next three years.

They are present in every cell of the body and carry the genetic information needed for that cell to develop. Genes, which are units of information, are "encoded" in the DNA. Human cells normally have 46 chromosomes which can be arranged in 23 pairs. Of these 23, 22 are alike in males and females; these are called the "autosomes. Each member of a pair of chromosomes carries the same information, in that the same genes are in the same spots on the chromosome. However, variations of that gene "alleles" may be present.

The first is ordinary cell division "mitosis" , by which the body grows. In this method, one cell becomes two cells which have the exact same number and type of chromosomes as the parent cell. The second method of cell division occurs in the ovaries and testicles "meiosis" and consists of one cell splitting into two, with the resulting cells having half the number of chromosomes of the parent cell.

So, normal eggs and sperm cells only have 23 chromosomes instead of This is what a normal set of chromosomes looks like. Note the 22 evenly paired chromosomes plus the sex chromosomes. The XX means that this person is a female. The test in which blood or skin samples are checked for the number and type of chromosomes is called a karyotype, and the results look like this picture.

Many errors can occur during cell division. In meiosis, the pairs of chromosomes are supposed to split up and go to different spots in the dividing cell; this event is called "disjunction. This means that in the resulting cells, one will have 24 chromosomes and the other will have 22 chromosomes.

This accident is called "nondisjunction. Hence the scientific name, trisomy Research is currently aimed at trying to determine the cause and timing of the nondisjunction event.

Three to four percent of all cases of trisomy 21 are due to Robertsonian Translocation. In this case, two breaks occur in separate chromosomes, usually the 14th and 21st chromosomes.

There is rearrangement of the genetic material so that some of the 14th chromosome is replaced by extra 21st chromosome. So while the number of chromosomes remain normal, there is a triplication of the 21st chromosome material.

Some of these children may only have triplication of part of the 21st chromosome instead of the whole chromosome, which is called a partial trisomy These people have a mixture of cell lines, some of which have a normal set of chromosomes and others which have trisomy In cellular mosaicism, the mixture is seen in different cells of the same type.

In tissue mosaicism, one set of cells, such as all blood cells, may have normal chromosomes, and another type, such as all skin cells, may have trisomy The 21st Chromosome and Down Syndrome The chromosomes are holders of the genes, those bits of DNA that direct the production of a wide array of materials the body needs.

But the genes that cause Down syndrome appear to be exceptions. Which genes are involved? From years of research, one popular theory stated that only a small portion of the 21st chromosome actually needed to be triplicated to get the effects seen in Down syndrome; this was called the Down Syndrome Critical Region.

However, this region is not one small isolated spot, but most likely several areas that are not necessarily side by side. Right now, the question of which genes do what is highly speculative.

However, there are some suspects. Genes that may have input into Down syndrome include: Again, it is important to note that no gene has yet been fully linked to any feature associated with Down syndrome.

One of the more notable aspects of Down syndrome is the wide variety of features and characteristics of people with trisomy There is a wide range of mental retardation and developmental delay noted among children with Down syndrome.

The first possible reason is the difference in the genes that are triplicated. As I mentioned above, genes can come in different alternate forms, called "alleles. The second reason that might be involved is called "penetrance. Both reasons may be why there is such variation in children and adults with Down syndrome.

Toward the Next Century Researchers are busy in their attempts to map out the full structure of the chromosome, including the Human Genome Database. Because of the small size of the 21st chromosome and its association with Down syndrome, it is the second-most heavily mapped human chromosome.

Research is focusing on trying to identify genes and their effects when overexpressed. However, it would be a mistake to assume that the clinical features of Down syndrome are only due to a handful of genes being overexpressed. It is this complex arrangement that scientists will be addressing in the second century of Down syndrome research.



Nature of Health Science There is nothing more exciting than to understand the way our bodies operate. Health science, also known as biomedical science, deals. I originally introduced the term “orthorexia” in the article below, published in the October issue of Yoga Journal. Some of the things I said in the article are no longer true of me, or of what I currently believe.

Total 2 comments.
#1 11.09.2018 â 15:22 Gemanda:
An authoritative answer, informative ...

#2 20.09.2018 â 18:09 Sharky-Ifa:
I do not remember where I already saw a similar theme