Metabolism of Lipids
They are 4 types of macromolecules in our body:
1. Carbohydrates 2. Nucleic acids 3. Proteins 4. Lipids
The first three types are polymers (composed of repeating subunits). However, lipids
ar
Lipids are organic macromolecules, heterogeneous, hydrophobic, compartmentalized
(because of their insolubility) in 1. Membranes 2. as droplets of triacylglycerol (TAG)
3. Transported in the blood in association of protein like lipoprotein (LP) particles or
albumin
NP
LDL
Heterogenous: they are not polymers + similarities among lipids are few (the main one
they are hydrophobic)
Functions: Energy, structures (membranes that permits partitioning of the aqueous
contents and subcellular structures), molecular precursors (ex. fat-soluble vitamins,
signaling molecule (inositol), steroid hormones, eicosanoids)
GENERAL VIEW:
There are many forms of lipids. They can be found as fatty acids (FA) which can be
saturated or monounsaturated (cis vs trans) or polyunsaturated. Also, they can be found
as glycerolipids (ex. diglyceride & triglyceride (also known as triacylglyceride TAG)),
glycerophospolipids (PL) (glycerol with 2 fatty acids and phosphate group with small
hydrophilic group (ex. Choline, serine, inositol, ethanolamine), sphingolipids (SL) which
has sphingosine backbone which is attached to a fatty acid and another group
(phosphorylcholine in sphingomyelin, monosaccharide in cerebrosides, cluster of sugars
in ganglioside). Also, they can be found as steroids such as cholesterol (CH) and
cholesterol ester (CE).
Page: 1
, Fatty acids can be classified based on multiple criteria
Most abundant fatty acids 16-18 carbon
Even chains are dominant (more common than odd ones)
Saturated means there is no double bonds while unsaturated means they have double
bonds and unsaturated could be mono or poly
Unsaturated could be cis which will result in a kink or trans (no kinks)
Branched and hydroxy are not important in this course
Essential means we must get them from diet while non-essential means we can
synthesize them in our bodies
Double bonds in FA are always spaced at three-carbon intervals.
Ex. Arachidonic acid 20:4
(20 carbon with 4 double bonds, )
The addition of double bonds decreases the melting temperature (Tm) of a fatty acid.
However, increasing the chain length increases the Tm.
Membrane lipids typically contain unsaturated long chain fatty acid (LCFA) to maintain
fluidity with cis orientation which will result in a kink (more space between FAs)
18:0
16:0
Essential and
18:1 precursors for the
14:0
longer fatty acids
12:0
,15 18:2
18:3
20:5 5,8,11,14,17
18:3
22:6 4,7,10,13,16,19
20:4
Page: 2
They are 4 types of macromolecules in our body:
1. Carbohydrates 2. Nucleic acids 3. Proteins 4. Lipids
The first three types are polymers (composed of repeating subunits). However, lipids
ar
Lipids are organic macromolecules, heterogeneous, hydrophobic, compartmentalized
(because of their insolubility) in 1. Membranes 2. as droplets of triacylglycerol (TAG)
3. Transported in the blood in association of protein like lipoprotein (LP) particles or
albumin
NP
LDL
Heterogenous: they are not polymers + similarities among lipids are few (the main one
they are hydrophobic)
Functions: Energy, structures (membranes that permits partitioning of the aqueous
contents and subcellular structures), molecular precursors (ex. fat-soluble vitamins,
signaling molecule (inositol), steroid hormones, eicosanoids)
GENERAL VIEW:
There are many forms of lipids. They can be found as fatty acids (FA) which can be
saturated or monounsaturated (cis vs trans) or polyunsaturated. Also, they can be found
as glycerolipids (ex. diglyceride & triglyceride (also known as triacylglyceride TAG)),
glycerophospolipids (PL) (glycerol with 2 fatty acids and phosphate group with small
hydrophilic group (ex. Choline, serine, inositol, ethanolamine), sphingolipids (SL) which
has sphingosine backbone which is attached to a fatty acid and another group
(phosphorylcholine in sphingomyelin, monosaccharide in cerebrosides, cluster of sugars
in ganglioside). Also, they can be found as steroids such as cholesterol (CH) and
cholesterol ester (CE).
Page: 1
, Fatty acids can be classified based on multiple criteria
Most abundant fatty acids 16-18 carbon
Even chains are dominant (more common than odd ones)
Saturated means there is no double bonds while unsaturated means they have double
bonds and unsaturated could be mono or poly
Unsaturated could be cis which will result in a kink or trans (no kinks)
Branched and hydroxy are not important in this course
Essential means we must get them from diet while non-essential means we can
synthesize them in our bodies
Double bonds in FA are always spaced at three-carbon intervals.
Ex. Arachidonic acid 20:4
(20 carbon with 4 double bonds, )
The addition of double bonds decreases the melting temperature (Tm) of a fatty acid.
However, increasing the chain length increases the Tm.
Membrane lipids typically contain unsaturated long chain fatty acid (LCFA) to maintain
fluidity with cis orientation which will result in a kink (more space between FAs)
18:0
16:0
Essential and
18:1 precursors for the
14:0
longer fatty acids
12:0
,15 18:2
18:3
20:5 5,8,11,14,17
18:3
22:6 4,7,10,13,16,19
20:4
Page: 2
