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.
A type of virus that has RNA instead of DNA as its genetic material. It uses an enzyme called reverse transcriptase to become part of the host cells' DNA. This allows many copies of the virus to be made in the host cells. The virus that causes AIDS, the human immunodeficiency virus (HIV), is a type of retrovirus.hen a retrovirus infects a cell, it makes a DNA copy of its genome that is inserted into the DNA of the host cell. There are a variety of different retroviruses that cause human diseases, including the common cold, some forms of cancer, and AIDS.