Question

The specialized functions of different membranes are largely determined by the proteins they contain. Membrane lipids are amphipathic molecules, composed of a hydrophilic portion and a hydrophobic portion. All cell membranes have the same lipid bilayer structure, with the _______ of the phospholipids facing into the interior of the membrane?

1) amphipathic
2) hydrophobic
3) phosphatidylserine
4) cholesterol
5) lipid bilayer
6) phospholipids
7) fatty acid tails
8) lipid monolayer proteins
9) glycolipids
10) lipids
11) sterols
12) hydrophilic head groups
13) phosphatidylcholine
14) sugars

Answer 1

The hydrophobic portions of phospholipids face the interior of the cell membrane. These amphipathic molecules are arranged in a bilayer, with hydrophilic heads contacting water and hydrophobic tails facing each other, forming the core of the membrane.

Step-by-step explanation:

All cell membranes have the same lipid bilayer structure, with the hydrophobic portions of the phospholipids facing into the interior of the membrane. This arrangement is due to the amphipathic nature of the membrane lipids which are composed of both a hydrophilic head and a hydrophobic tail. The hydrophilic heads are in contact with the aqueous environment, both inside and outside the cell, while the hydrophobic tails face each other away from the water, forming the interior of the membrane.

The phospholipid bilayer forms the fundamental structure of the cell membrane but includes various proteins like integral and peripheral proteins. Integral proteins are embedded within the membrane and can form channels that selectively allow materials to pass through. The lipid bilayer itself provides a barrier that separates the cell's internal fluid from the external environment.