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.
If a sequence of bases on one strand of DNA is CTGCTA, then the other DNA strand will be GACGAT. The Structure of DNA, RNA, and DNA's Arrangement in Cells DNA is Composed of Four Types of Nucleotides Since the 1920's, scientists have known that the DNA molecule is a very long polymer, or string of repeating units. The small units, or monomers that make up DNA are called nucleotides. Nucleotides Each nucleotide in DNA consists of three parts.