The three-domain system is a biological classification introduced by Carl Woese et al.in 1977[1][2] that divides cellular life forms into archaea, bacteria, and eukaryote domains. In particular, it emphasizes the separation of prokaryotes into two groups, originally called Eubacteria (now Bacteria) and Archaebacteria(now Archaea). Woese argued that, on the basis of differences in 16S rRNA genes, these two groups and the eukaryotes each arose separately from an ancestor with poorly developed genetic machinery, often called a progenote. To reflect these primary lines of descent, he treated each as a domain, divided into several different kingdoms. Woese initially used the term "kingdom" to refer to the three primary phylogenic groupings, and this nomenclature was widely used until the term "domain" was adopted in 1990.[2]
Parts of the three-domain theory have been challenged by scientists such as Radhey Gupta, who argues that the primary division within prokaryotes should be between those surrounded by a single membrane, and those with two membranes.
X-rays and CT scans and MRIs
51% of young people feel deeply sad or hopeless every day for a prolonged period of time which leads to depression.
Why there is depression in young people:
- Exams, arguments with family or friends, switching schools, or moving homes are just a few examples of the life events that can make young people depressed and anxious.
- The young person may develop depression if the depressive emotions persist for several weeks or months and interfere with daily life.
- Feeling irritable, having problems sleeping, feeling unworthy or guilty, eating more or less than normal, and gaining or losing weight are all signs of depression in young adults.
- Depression can be brought on by a variety of variables, including life experiences, genetic predispositions, hormones, or any combination of those things.
Learn more about the Depression with the help of the following link:
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Emerging diseases are those whose incidence in humans has increased in the past 2 decades or threaten to increase in the near future. Re-emerging diseases are are diseases that reappear after they have been on a significant decline.