Class A (type D) CpG ODNs (CpG-A ODNs) contain a central palindromic phosphodiester (PO) CpG sequence and a PS-modified 3â poly-G tail. The poly G tails form intermolecular tetrads that result in high molecular weight ordered structures.
Why does a tornado form when cold and hot air meet? The collision of warm and cold air is not the direct cause of a tornado, nor is it absolutely necessary. When a cold air mass pushes into a warm air mass (this is called a câ¦old front) the warmer, less dense air is forced upwards.
Best Answer: the central US is the world hot spot for them but not the only place. The majority of tornadoes occur in agricultural areas. Tornadoes need moisture to feed their parent thunderstorms and the instability associated with spring and summer warming. Crops need moisture to grow and the temperature variation associated with changing seasons.