1. What are the main classes of lipids?
2. Where are they found in the cell?
3. Where did they come from?
LIPIDS
hydrophobic or amphipathic small molecules
ribosome
mitochondrion
Rough endoplasmic
reticulum (ER)
cell membrane
cytoplasm
cytosol
lysosome
peroxisome
peroxisome
nucleus
smooth
endoplasmic
reticulum
free ribosome
Golgi complex
lipid droplet
monolayer
PL, C
CE
TAG
Fatty acids
• Free (toxic unless esterified)
• Esterifed in glycerophospholipids,
sphingolipids, glycerol lipids and
sterol lipids
Lipids Classes
1. What are the main classes of lipids?
2. Where are they found in the cell?
3. Where did they come from?
LIPIDS
hydrophobic or amphipathic small molecules
ribosome
mitochondrion
Rough endoplasmic
reticulum (ER)
cell membrane
cytoplasm
cytosol
lysosome
peroxisome
peroxisome
peroxisome
nucleus
smooth
endoplasmic
reticulum
free ribosome
Golgi complex
lipid droplet
CE
TAG
In membranes
In cell membrane and
lipid droplets
In lipid droplets
Fatty acids
• Free (toxic unless esterified)
• Esterifed in glycerophospholipids,
sphingolipids, glycerol lipids and
sterol lipids
Lipids Classes
1. What are the main classes of lipids ?
LIPIDS
2. Where are they found in the cell?
3. Where did they come from? Import /Export and Synthesis/Trafficking
ribosome
mitochondrion
Rough endo.
reticulum
cell membrane
cytoplasm
cytosol
lysosome
import
Circulating
FA C, GP
Lipoprotein
CE
GL
• LDL from liver
• Chylomicrons
lipoprotein from intestines
not to scale
nucleus
peroxisome
peroxisome
peroxisome
lipoprotein
smooth
endoplasmic
reticulum
free ribosome
FA
Golgi complex
not to scale
lipid droplet
FA
Exported FA from fat cells (adipocyte)
bind to serum albumin
lipoprotein
for transport to tissue
CE
GL
Circulating FA (grey
spacefill) imported
from adipoctyes bound to
protein: serum albumin;
FA to mitochondria for
oxidation/ATP prod.
not to scale
Circulating Lipoprotein
• VLDL exported from liver
(synthesized) lipids
• Chylomicrons exported from
intestines (ingested lipids)
IMPORT/EXPORT
1. What are the main classes of lipids?
2. Where are they found in the cell?
3. Where did they come from? Import and Synthesis/Trafficking
LIPIDS
synthesized in cytoplasm
Mostly in liver, mammary tissue
Rough
endo.
reticulum
ribosome
mitochondrion
cell membrane
cytoplasm
cytosol
FA
elongation
FA
lysosome
elongation,
desaturation
FA
elongation
PM
FA
GP
GL
GP1
peroxisome
C
ST
PM 2
SP
ER (smooth)
main site of
lipid synthesis
GP
SP
C
Golgi: sorts lipids
smooth
endoplasmic
reticulum
Golgi complex
lipid droplet
C
PM
CE
ST
GP
GP1
Cardiolipin and phosphatidyl glycerol
(2 lipids also found in bacteria, are
made in the mitochondrion
GL
SP2
Ceramide, a precursor of SP,
is made in mitochondria.