逆转录酶

• 辶(go; step)RADICAL
• 屰(reverse; opposite)PHONETIC

Going against the direction of others is the meaning of the character 逆.

• 車(vehicle; cart; car)RADICAL
• 專(specialize in; concentrate on)PHONO-SEMANTIC

A wheel keeps spinning in one direction, so it's called rotating or turning.

• 彐(hand holding brush (pictographic))ASSOCIATIVE
• 氺(water; flow)ASSOCIATIVE

A hand holding a pen writes flowing lines of characters like water – that is recording and registering.