Introduction In this assignment I am going to compare some areas of molecular revolution with genomics revolution.
Since the s the accumulation of spontaneous mutations in the DNA of organs and tissues has been hypothesized to underlie aging itself e. What are mutations, and why are they there?
DNA damage consists of chemical alterations in DNA structure, leading to a structure that can no longer serve as a substrate for faithful replication or transcription.
DNA damage cannot be copied to end up in daughter cells. DNA mutations are heritable changes in a DNA sequence of an organism, which can be part of a gene, a gene regulatory region, or some noncoding part of the genome. Mutations are usually introduced as a consequence of misreplication or misrepair, for example, due to the presence of DNA damage.
Hence, DNA damage can lead to mutations when it is not correctly repaired. Mutations can vary from point mutations, involving single or very few base pairs to large deletions, insertions, duplications, and inversions.
In organisms with multiple chromosomes, DNA from one chromosome can be joined to another and the actual chromosome number can be affected. Indeed, they fuel the survival of cells and organisms in times of stress. They are the substrate for evolution, which gave rise to different life forms.
In both prokaryotic and eukaryotic cells mutation rate can be greatly increased, causing many cells to die but also giving rise to cells with the necessary attributes to survive and expand. Cancer cells, for example, can undergo mutations in genes that control the mutation rate for example, genes involved in DNA repair.
Such "mutator phenotypes" allow them to accelerate the acquisition of novel attributes e. While in such cases mutations are detrimental for the host, they are beneficial for the cell.
In most cases, mutations will have adverse effects on both the host and the cell. In the somatic cells of multicellular organisms, however, mutations usually have adverse effects.
Gross chromosomal alterations The earliest and still the most popular way to look at mutations is by cytogenetic means. This necessarily precludes the detection of mutational events smaller than a few million base pairs and also limits the target tissue to cells in metaphase, usually white blood cells.
A noteworthy exception to this latter limitation is the original work of the late Howard Curtiswho with coworkers examined mouse liver parenchymal cell metaphase plates after partial hepatectomy and found considerably higher numbers of cells with abnormal chromosomes in old, compared with young, animals i.
Later, large structural changes in DNA were observed to increase with donor age in white blood cells of human individuals, from about 2—4 percent of the cells having chromosomal aberrations in young individuals to about six times higher in the elderly.
The recent use of more advanced methods, such as chromosome painting, have confirmed the increase in cytogenetic damage with age in both human and mouse.
In both human and mouse lymphocytes the increase in chromosome aberrations appeared to be exponential. Mutations detected in selectable marker genes With the development of tests based on selectable endogenous marker genes, it became possible to assess mutation frequencies at these loci in T-cells from human and animal donors for a review see Vijg, Using the hypoxanthine phosphoribosyl transferase HPRT locus test, investigators have shown that mutation frequencies at this locus increase with donor age.
In mice mutation frequencies have been reported from about 5 x in young animals to about 3 x in middle aged mice Dempsey et al. However, in both mice and humans these values could be underestimates, due to the loss of HPRT mutants in vivo or in vitro. Indeed, results from Grist et al.
Values higher than HPRT were also found with other assays involving selectable target genes. The discrepancy has been explained in terms of the inability of the HPRT test to detect mitotic recombination events HPRT is X-linked and a relatively strong in vivo selection against mutants.
In mice subjected to caloric restriction, the only intervention demonstrated to increase life span Masoro,HPRT mutation frequencies were found to increase with age at a significantly slower rate than in the animals that fed at will. They saw an age-associated accumulation of mutations in the mice that fed at will, but not in the mice that experienced calorie restriction.Free skeletal system papers, essays, and research papers.
Sex Linked Diseases. Albinism: Albinism is a congenital disorder in which there is little or completely no production of melanin in hair, skin and iris of the eyes. Hence albinos (people suffering from albinism) have light colored skin, hair and eyes.
Alzheimer’s Disease: Alzheimer’s disease is the most common form of dementia which. The cause of albinism is a mutation in one of several genes. Each gene provides the chemical code instruction for making one of the several proteins involved in the production of melanin.
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Barth Syndrome: A rare but serious sex linked genetic disorder, the Barth syndrome is caused due to mutations or alterations in the BTHS gene. The gene is located on the long arm of X chromosome. This disorder primarily affects the heart. The term political correctness (adjectivally: politically correct; commonly abbreviated to PC or P.C.) is used to describe language, policies, or measures that are intended to avoid offense or disadvantage to members of particular groups in society.
Since the late s, the term has come to refer to avoiding language or behavior that can be seen as excluding, marginalizing, or insulting.