But Social Security was never meant to be the only source. of income for people when they retire. Social Security. replaces about 40 percent of an average wage earnerâs income. after retiring, and most financial advisors say retirees will. need 70 percent or more of pre-retirement earnings to live. comfortably.
DNA viruses. Originally viruses were grouped and named according to the disease they cause, even if they are not closely related. For example Hepatitis A is an RNA virus and Hepatitis B is a DNA virus, but they both cause liver disease.Nowadays, however, viruses are grouped by their shared characteristics in much the same way as plants and animals are. All but one of the DNA virus families use double stranded DNA as their infectious 'code'.riginally viruses were grouped and named according to the disease they cause, even if they are not closely related. For example Hepatitis A is an RNA virus and Hepatitis B is a DNA virus, but they both cause liver disease.
When RNA viruses invade the human organism, they inject their RNA into the cytoplasm of the host cell. Once they are inside the cytoplasm, RNA can be used to synthesize proteins, and, eventually, to form replica viruses. There is a special category of RNA viruses, which is called retroviruses. These viral agents contain protein known in biology as reverse transcriptase. Once the retrovirus injects its RNA into the cell, reverse transcriptase transcribes the RNA into DNA (the operation that is the reverse of normal transcription).