A virus is basically a shell of DNA. It floats around until it finds a cell to latch onto. It then tricks the cell into absorbing the virus and the virus unleashes the DNA its carrying telling the cell to quit doing its job, and make more of the virus. <span />
There are 4 nucleotides. Guanine (G), Cytosine (C), Thymine (G) and Adenine (A).
C and T are called pyrimidines, and are longer than G and A.
G and C connect using 3 hydrogen bonds, but A and T bond using only 2.
Nitrogen fixation- atmospheric nitrogen is assimilated into organic compounds especially by certain microorganisms as part of the nitrogen cycle.