Cell Membrane Structure
Membrane lipids have: Polar/hydrophilic heads and nonpolar/hydrophobic fatty acid tails
● Phospholipids are the most abundant group of membrane lipids - they will always have a polar
head that contains a phosphate group and other hydrophilic atoms such as nitrogen. Hydrophilic
literally means “water-loving”. There are a huge variety of phospholipids, each with critical roles in
the overall functioning of the membrane - compositions vary between organs, between tissues
within organs, and even within a single cell, with the top (or apical) membrane of the cell very
different than the bottom (or basal) membrane.
● Glycolipids: are sugar-bound lipids - these sugars make their heads polar , too.
● Cholesterol makes up about 20% of the membrane lipids. It decreases membrane permeability by
packing in between other lipids. This important shield prevents substances from entering or leaving
without permission.
○ A popular area of research right now is learning how cholesterol organizes where the
protein components - channels and receptors - are located within the membrane.
Fatty acids of membrane
lipids :
● Unlike triglycerides, membrane lipids usually only have two fatty acid tails. These long carbon
chains are nonpolar and hydrophobic (hydrophobic literally means “water-fearing”).
● Fatty acid tails are saturated or unsaturated, and these differences provide even more fine-tuning
and adjustment for membrane functioning.
● More saturated fatty acids will provide greater stability , whereas more polyunsaturated fatty acids
provide for more flexibility in the membrane.
● The unsaturated fatty acids are also crucially involved with sending signals from the membrane
down deeper into the cytoplasm of the cell.
Membrane lipids have: Polar/hydrophilic heads and nonpolar/hydrophobic fatty acid tails
● Phospholipids are the most abundant group of membrane lipids - they will always have a polar
head that contains a phosphate group and other hydrophilic atoms such as nitrogen. Hydrophilic
literally means “water-loving”. There are a huge variety of phospholipids, each with critical roles in
the overall functioning of the membrane - compositions vary between organs, between tissues
within organs, and even within a single cell, with the top (or apical) membrane of the cell very
different than the bottom (or basal) membrane.
● Glycolipids: are sugar-bound lipids - these sugars make their heads polar , too.
● Cholesterol makes up about 20% of the membrane lipids. It decreases membrane permeability by
packing in between other lipids. This important shield prevents substances from entering or leaving
without permission.
○ A popular area of research right now is learning how cholesterol organizes where the
protein components - channels and receptors - are located within the membrane.
Fatty acids of membrane
lipids :
● Unlike triglycerides, membrane lipids usually only have two fatty acid tails. These long carbon
chains are nonpolar and hydrophobic (hydrophobic literally means “water-fearing”).
● Fatty acid tails are saturated or unsaturated, and these differences provide even more fine-tuning
and adjustment for membrane functioning.
● More saturated fatty acids will provide greater stability , whereas more polyunsaturated fatty acids
provide for more flexibility in the membrane.
● The unsaturated fatty acids are also crucially involved with sending signals from the membrane
down deeper into the cytoplasm of the cell.
