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.
A: Tornadoes happen when warm, moist air masses and cold, dry air masses collide to cause large thunderstorms. Not all thunderstorms produce tornadoes, and scientists are not certain which factors are directly responsible for their formation. They do know that in many cases, horizontal spinning movements in the air can be lifted vertically.