1 Chronic bronchitis: A form of COPD characterized by a chronic productive cough. 2  Emphysema: Lung damage allows air to be trapped in the lungs in this form of COPD. 3  Difficulty blowing air out is its hallmark. 4  Acute bronchitis: A sudden infection of the airways, usually by a virus.
There are only 46 DNA molecules ( 23 pairs) in human somatic cell. There are about 22000 genes and close to 3.2 billion base pairs in total.
DNA molecules are composed of four nucleotides, and these nucleotides are linked together much like the words in a sentence. Together, all of the DNA sentences within a cell contain the instructions for building the proteins and other molecules that the cell needs to carry out its daily work.