Optic components: cornea, lens, vitreous body, and the aqueous body b. Not an optic component of the eye: retina 87. Glaucoma is a state of elevated pressure within the eye that occurs when ___ is obstructed so that the _____ is not reabsorbed as fast as it is secreted. a. Occurs when the scleral venous sinus is obstructed so the aqueous humor is not reabsorbed as fast as it is secreted.
Substitution mutation. Definition. A type of point mutation in which a single nucleotide is substituted with (or exchanged for) a different nucleotide that may result in an altered sequence of amino acid during translation, which may render the newly synthesized protein ineffective. Supplement.
A substitution is a mutation that exchanges one base for another (i.e., a change in a single chemical letter such as switching an A to a G). Such a substitution could: 1  change a codon to one that encodes a different amino acid and cause a small change in the protein produced.2  For example, sickle cell anemia is caused by a substitution in the beta-hemoglobin gene, which alters a single amino acid in the protein produced. For example, sickle cell anemia is caused by a substitution in the beta-hemoglobin gene, which alters a single amino acid in the protein produced. 2  change a codon to one that encodes the same amino acid and causes no change in the protein produced. 3  These are called silent mutations.