Heat shock proteins (HSPs) are in a class of proteins called molecular chaperones. (Kiang, J.; G, Tsokos. 1998). They are present in both eukaryotes and prokaryotes, in the cytosol, mitochondria, endoplasmic reticulum and the nucleus. In humans they have a relatively long half-life of about 2 days (Baneyx, F. 2008). HSP70 are a specific type which are normally found in very low amounts within a cell, they can be expressed in response to external stimuli. This external stimuli can be sub lethal heat shock (SLHS) hence the name heat shock proteins (Baneyx, F. 2008), this stimulus causes more of the proteins to be produced (Pugsley, A. 1989). In addition to being expressed due to SLHS they can also be expressed in response to amino acid analogs, heavy metals …show more content…
According to this theory the mitochondria would have once been an aerobic bacteria that has been engulfed by a larger cell, but wasn’t destroyed as a mutually beneficial relationship was formed. It is widely accepted that some if not all modern eukaryotic cells originated in this form. This theory also explains why the mitochondria contains its own ribosomes (Bolsover, S., Hyams, J., Jones, S., Shephard, E. and White, H. 1997) and circular genome very similar to that of a bacterial genome (Allison, L. 2007) also why the mouse mitochondrial DNA was shown as more closely related to the prokaryotic sequences than to the house mouse