Gram-negative bacteria transparent becuse of hydrolipids not dyes used for this kind of graph. Periplasmic space between the inner and outer membranes. Inner membrane typical biological membrane composed of phospholipids primarily: fatty acid chain facing each other to form bilayer structure, hydrophilic head region forms outside, energetically most stable structure. Small molecules like water can be transported but prevent transport of charged molecules, like iron. Proteins in cytoplasmic membrane including transport system. Site of proton motive force or proton gradient: outside of membrane, higher concentration of protons which creates gradient, important for generating energy. Gram-positive bacteria has only peptidoglycan outside the inner membrane, no additional membrane. No periplasmic space in gram positive bacteria. Same number of hte molecule ions er volume. Many proteins including enzymes that can modify. Nucleases degrade incoming dna molecules, bacteria do not take up genetic material, might harm cells. P binding proteins taking up nutrients from environments part of abc transport.