degeneration. deterioration; change from a higher to a lower form, especially change of tissue to a lower or less functionally active form. When there is chemical change of the tissue itself it is true degeneration; when the change consists in the deposit of abnormal matter in the tissues, it is infiltration.apetoretinal degeneration degeneration of the pigmented layer of the retina. transneuronal degeneration atrophy of certain neurons after interruption of afferent axons or death of other neurons to which they send their efferent output.
There are four different DNA nucleotides, each defined by a specific nitrogenous base: adenine (often abbreviated A in science writing), thymine (abbreviated T), guanine (abbreviated G), and cytosine (abbreviated C) (Figure 2).
Split and merge into it. Answer by Mike754. Confidence votes 1.1K. A nucleotide unit is a single nucleotide within a nucleic acid polymer (DNA, RNA, etc). Each nucleotide unit is made of a sugar, phosphate group and nitrogen base.The nitrogen base of each unit is used to identify it. nucleotide is a monomer of a nucleic acid consisting of 3 parts.  These 3 parts include a pentose sugar, a phosphate  group, and a nitrogenous base. The nitrogenous bases â¦  include purines (adenine and guanine) and pyrimidines (cytosine and  thymine).