What is the function of a prepositional phrase?
to join two independent clauses
to join together ideas in a sentence
to join two dependent clauses
to join together phrases

To join together phrases

some attention getter quotes to support your thesis regarding brain work could be the following: :

a. storage capacity of your brain is virtually unlimited.

b. your brain produces sufficient electricity to light-up a small bulb.

c. different brain circuits are involved with reading aloud or silently.

d. your brain by itself does not feel pain.

e. reading allows your brain to download info directly.

f. brains of two musicians performing together can synchronize.

the krebs cycle and electron transport occur in the mitochondria, though other than that i would need to know more information.