intro to lipids (10) Flashcards
carbons in TGs vs carbons in carbs, which ones have a lower oxidation state?
the carbons in triglycerides
how many kcal/gram in carbs?
4 kcal/g
how many kcal/gram in protein?
4 kcal/g
how many kcal/gram in fat?
9 kcal/g
how many kcal/gram in alcohol?
7 kcal/g
why do carbohydrates have twice the dry weight as TGs?
because TGs are stored in an anhydrous state whereas cabs are bound to water
describe the double bonds in polyunsaturated fatty acids
the bonds are neither adjacent nor conjugated
this allows the structure to not be as easily oxidized
also the double bonds are almost always separated by a methyl group
why type of fatty acid is the following describing?
“ highly flexible, energetically favorable”
saturated fatty acids
which will have a lower melting temperature?
a TG with side chains containing double bonds or without double bonds
a TG with double bonds with have a lower melting point (their double bonds interfere with packing)
what is the common name for C14?
myristic
what is the common name for C16 with no double bonds?
palmitic
what is the common name for C16 with 1 double bond?
palmitoleic
what is the common name for C18 with no double bonds?
stearic
what is the common name for C18 with 1 double bond?
oleic
what is the common name for C18 with 2 double bonds?
linoleic
what is the common name for C18 with 3 double bonds?
linolenic
what is the common name for C20 with 4 double bonds?
arachidonic
list the 3 components of bile
bile acids
phosphatidyl choline
cholesterol
what is required for pancreatic lipase activation?
requires the formation of a complex with colipase & a droplet of emulsified lipid which will stabilize the “open” confirmation and allow access to substrate while shielding against bile salts (which would inactivate the enzyme)
where are most TGs hydrolyzed? what enzyme does this?
pancreatic lipase in the duodenum and proximal jejunum
what is colipase?
a protein that is secreted as the an inactive precursor by the pancrease and activated in the duodenum by trypsin. it is necessary for lipase to have access to lipid substrates
what are the two main products after TG has been hydrolyzed by pancreatic lipase?
2-MAG
NEFA
what is the major FA transporter in enterocytes?
FATP5 from the fatty acid transport protein family
what aquaporin mediates glycerol transport?
AQP3
list the 3 main causes of steatorrhea
- failure of bile production of blockage of bile flow
- exocrine pancrease dysfunction or obstruction of pancreatic duct
- failure of uptake into intestinal mucosal cells
for long chain fatty acids, answer the following:
requires pancreatic lipase?
requires micelle formation?
present in feces?
requires pancreatic lipase? yes
requires micelle formation? yes
present in feces? minimal
for medium chain fatty acids, answer the following:
requires pancreatic lipase?
requires micelle formation?
present in feces?
requires pancreatic lipase? no
requires micelle formation? no
present in feces? no
for short chain fatty acids, answer the following:
requires pancreatic lipase?
requires micelle formation?
present in feces?
requires pancreatic lipase? no
requires micelle formation? no
present in feces? substantial
where is the primary site of absorption for:
LCFA
MCFA
SCFA
LCFA: small intestine
MCFA: small intestine
SCFA: colon
what is the origin for the following:
LCFA
MCFA
SCFA
LCFA: in the diet as TGs
MCFA: in the diet as TGs
SCFA: bacterial conversion of nonabsorbed CHO
what is the requirement for TGs to be able to be transported through the lymph and blood?
they must be packaged into a lipoprotein particle: chylomicrons
what is the name of the principal protein component of nascent chylomicrons as they are produced in the intestinal mucosa?
Apo-B48
what does the metabolism of lipoproteins depend on?
upon molecular recognition between various enzymes (or receptors) and the apoproteins on the surfaces of the various lipoprotein particles
