All eukaryotic cells have within them a variety of different structures called organelles. Organelles are small and function much like organs function in a large organism. Some organelles are responsible for gathering cell energy, others for controlling cell activities.Note-although this organelle is also found animal cells, the vacuoles from plant cells are drastically bigger and play a much more important role in the processes of the cell.
HIV crossed from chimps to humans in the 1920's in what is now the Democratic Republic of Congo. This was probably as a result of chimps carrying the Simian Immunodeficiency Virus (SIV), a virus closely related to HIV, being hunted and eaten by people living in the area.
Untreated, HIV reduces the number of CD4 cells (T cells) in the body. This damage to the immune system makes it harder and harder for the body to fight off infections and some other diseases. Opportunistic infections or cancers take advantage of a very weak immune system and signal that the person has AIDS. Learn more about the stages of HIV and how to know whether youâre infected. What Is HIV? HIV stands for human immunodeficiency virus. It is the virus that can lead to acquired immunodeficiency syndrome, or AIDS, if not treated. Unlike some other viruses, the human body canât get rid of HIV completely, even with treatment.