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).
The monomers of DNA are called nucleotides, and the polymer is a polynucleotide. There are four different nucleotides in DNA called A, T, G, and C for the nitrogenous base sidegroup (adenine, thymine, guanine, and cytosine respectively) attached to the sugar-phosphate backbone (deoxyribose-phosphate) of a nucleotide. DNA is a nucleic acid. Nucleic acids are polymers of nucleotides (also called mononucleotides).   The nucleotides in DNA are deoxyribonucleotides.   Each nucleotid â¦ e consists of a pentose (5-carbon) sugar, a nitrogen-containing base and a phosphate group.