Gaaffii 1
Qormaata galuumsa kutaa 12ffaa Baayoloojii, bara 2005 A.L.I (2013)
Which one of the following is the main constituent of biological membranes?
- A.Phospholipids
- B.Glycoproteins
- C.Glycolipids
- D.Cholesterol
Deebii fi ibsa ilaalaa
Deebii: A Phospholipids
Maaliif
Every biological membrane is built as a double sheet of phospholipids. Each phospholipid has a water loving head and two water hating tails, so in water the molecules line up automatically with the tails facing inward and the heads facing out. That bilayer is the sheet itself, and everything else sits inside it. Cholesterol is tempting because animal membranes really do contain it, but it is a small amount tucked between the phospholipids to control how stiff the membrane is, not the material the membrane is made from.
