Midterm - Lipids Flashcards
are lipids soluble or insoluble in organic solvents
soluble
how many different lipid species have been characterized
10,000
what do lipids provide
energy
major component of cell and organelle membranes
saturated lipids
max number of H atoms
single bonds
unsaturated lipids
missing H atoms
double bonds
cis or trans configurations
what are the 3 types of fatty acids
saturated
monounsaturated
polyunsaturated
essential fatty acid
linoleum acid (produced in plants)
why are these fatty acids essential
humans lack enzymes needed to insert double bonds beyond delta-9 position
eicosanoids
metabolites of 20-carbon fatty acids
what are eicosanoids produced by
most cells in the body
characteristics of eicosanoids
hormone-like but function locally
functions of eicosanoids
inflammation
platelet aggregation
blood pressure
implications for disease
what is the main dietary lipid
triglycerides
example of a major storage lipid
triglycerides
what processes are triglycerides critical in
lipogenesis
lipolysis
transported in lipoproteins
what are the 3 triglyceride structures
monoacylglycerol
diacylglycerol
triglyceride/triacylglycerol
what determines the physicochemical properties
fatty acid composition
are phospholipids or triglycerides more polar
phospholipids (hydrophilic phosphate head group)
primary functions of phospholipids
components of membranes
source of active fatty acids (eicosanoid synthesis)
anchors membrane proteins
intracellular signalling
what are sterols
steroid alcohols (monohydroxy)
structural features of sterols
free or esterified with a fatty acid
what are sources of cholesterol
meat, eggs, endogenous production
primary functions of sterols
essential component of membranes
what are sterols a precursor for
bile acid production
steroid sec hormone production
vitamin D synthesis
what are digested lipids emulsified by
conjugated bile acids
mixed micelles
small spherical complexes containing lipid digestion products plus bile salts
what can mixed micelles access
spaces between microvilli in intesitne
what are the 3 brush border enzymes in lipid absorption
pancreatic lipase
cholesterol esterase
phospholipase
what is lipoprotein classification determined by
1.ratio of lipid-to-protein (affects density)
2. specific apolipoprotein content (affects receptor interactions)
what do chylomicrons increase in
circulation after a meal - enter at a slow rate
when do chylomicrons peak
30min to 3h after eating
where is lipoprotein lipase located
surface of endothelial cells lining small blood vessels and capillaries
what is LPL expressed by
adipose and muscle
what is LPL activated by
ApoC in chylomicrons
what does LPL hydrolyze
the TAG in chylomicrons into 2-MAG + 2 fatty acids
when are chylomicrons referred to as a “chylomicron remnant)
when they become TAG depleted
what happens to chylomicron remnants
they are removed from circulation through ApoE-mediated interactions with a receptor in the liver
what percentage of blood cholesterol in LDL is in a fasting subject
60%
what is VLDL
the main transporter of newly synthesized hepatic TAG
what are the 3 fates of cholesterol in the liver
- converted into bile acids to replenish bile acid pool
- secreted “as is” directly with bile to be eliminated as faces
- packaged into VLDL and sent around the body
what does LDL do with cholesterol
delivers it for essential functions but can also deposit it in unwanted places
what do higher HDL levels mean`
more cholesterol returning to liver
where do lipids fit into gluconeogenesis
the glycerol backbone is glucogenic
where do lipids fit into the Krebs cycle
fat oxidation via acetyl CoA
what is the recommended caloric intake for men
2500kcal/day
what is the recommended caloric intake for women
2000kcal/day
what percentage should protein be of daily calories
10-35% (max of 218g)
what percentage should carbohydrates be of daily calories
45-65% (max of 406g)
what percentage should fats be of daily calories
20 - 35% (max of 97g)
for people with high blood cholesterol, what does decreasing dietary cholesterol do
decreases LDL
trans fats
unsaturated fatty acids with at least one double bond in the trans configuration
what are the 2 kinds of trans fats
industrial and natural
when are industrial trans fats produced
hydrogenation of vegetable oils
what does partial hydrogenation result in
double bonds being converted from cis to trans
what does complete hydrogenation result in
all double bonds becoming fully saturated
what is the relationship between hydrogenation and saturation
increase in the amount of hydrogenation, increases the degree of saturation
where are trans fats found naturally
ruminant fat
what percentage of trans fat does milk contain
4-8%
when are natural trans fats made
in the rumen through bacterial fermentation
what are affects of a high intake of industrial trans fatty acids
increase in: LDL cholesterol, total cholesterol, inflammation
decrease in: HDL cholesterol
what are trans fats linked to
CVD risk
