There are three types of DNA Mutations: base substitutions, deletions and insertions. Single base substitutions are called point mutations, recall the point mutation Glu -----> Val which causes sickle-cell disease.
Epipelagic Zone (top zone of the ocean). The sunlight zone Mesopelagic Zone (middle of the ocean). The twilight or mid water zone Bathypelagic Zone (from Greek “bathýs” for deep) The midnight or dark zone