hydrophobic

MIT Biology Hypertextbook: Chemistry Review

1.5 Hydrophobic Interactions Nonpolar molecules cannot form H-bonds with H2O, and are therefore insoluble in H2O. These molecules are known as hydrophobic (water hating), as opposed to water loving hydrophilic molecules which can form H-bonds with H2O. Hydrophobic molecules tend to aggregate together in avoidance of H2O molecules; hydrophobic interactions are clearly demonstrated when you put an oil drop on water. This attraction/repulsion is known as the hydrophobic (fear of water) force. To understand the energetics driving this interaction, visualize the H2O molecules surrounding a "dissolved" molecule attempting to form the greatest number of hydrogen bonds with each other. The best energetic solution involves forcing all of the nonpolar molecules together, thus reducing the total surface area that breaks up the H2O H-bond matrix.

1.1 Membrane Structure and Composition

hydrophobic hydrocarbon chains of the phospholipid. The tails of the

phospholipids orient towards each other creating a hydrophobic environment

to enter the hydrophobic interior of the membrane bilayer.

of the phospholipid to pass fully through the highly hydrophobic interior of

the membrane, and for the hydrophobic tails to be exposed to the aqueous

Membrane Transport Problem Answers

The intramembranous portion of the protein is highly hydrophobic, and it

unfavorable for them to pass through the hydrophobic interior of the

Lipids

The lipids we'll be studying are phospholipids, the primary components of cellular membranes. Phospholipids are amphipathic; that is, they are both hydrophilic and hydrophobic. The "head" of a lipid moleule is negatively charged phosphate group and the two

"tails" are highly hydrophobic hydrocarbon chains.

Phospholipid tails will congregate together to form a local hydrophobic environment. This leaves the charged

Membrane Proteins

hydrophobic inner layers of the plasma membrane?

hydrophilic and one hydrophobic . A hydrophilic domain (consisting of

extracellular medium, a hydrophobic domain in the middle of the amino

amino acids having hydrophobic side chains, exists comfortably in the

hydrophobic inner layers of the plasma membrane. Because these

acids) alternate with hydrophobic domains. The protein chain as a whole

hundreds of serpentine transmembrane proteins involves 7 hydrophobic

Receptors

the plasma membrane via their hydrophobic transmembrane domains, are

3.4 Primary through Quartenary structure

A-helices are most commonly made up of hydrophobic amino acids, because