26. Prokaryotes

Gram-negative bacteria have __________ peptidoglycan than gram-positive cells, and their cell walls are __________ complex structurally.

A gram-negative cell wall consists of __________.

Bacteria that __________ tend to have abundant internal membranes.

Bacterial flagella have a very complex structure composed of 42 distinct proteins. What is the most likely explanation for the evolution of these complex structures?