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).
A nucleotide consists of three components:   1. A 5-carbon sugar (deoxyribose for DNA or ribose for RNA)   2. A nitrogenous base (adenine, cytosine guanine and thymine (â¦ or uracil in RNA)   3.A phosphate group.he three components that create a DNA nucleotide are a phosphate group, a nitrogenous base [this will be either Adenine, Guanine, Cytosine, or Thymine], and a Sugar [deoxyrib â¦ ose, which is how we get the D in DNA]. 5 people found this useful. Rhonda Pittman.