Kaplan Biochemistry: Chapter 11 Lipid and AA Metabolism Flashcards
four components that make up a micelle
free fatty acids, cholesterol and 2 monoglycerol and bile salts
bile salts are actively reabsorbed in the ____
ileum
before being absorbed, fats in the lumen of the intestine must be
emulsified, by the help of bile salts, pigements, and cholesterol.
micelles of fat diffuse to the brush boarder where they are ______ to formed ___ and ___ ____, to form ____
micelles of fat diffuse to the brush boarder where they are REESTERFIED to formed TRIACYGLYCEROLS and CHOLESTEROL ESTERS, to form CHYLOMICRONS
once the micelle becomes a chylomicron in the villi, the chylomicron leaves the intestine via ____, and re-enter the blood stream via the ___ ___
once the micelle becomes a chylomicron in the villi, the chylomicron leaves the intestine via LACTEALS, and re-enter the blood stream via the THORACIC DUCT.
fall of insulin levels activate ___-__ ___ that hydrolyzes triacylglycerols
hormone-sensitive lipase
in addition to insulin, what other chemical can activate hormone-sensitive lipase?
epinephrine.
where can you find hormone-sensitive lipase
in adipose tissue.
cortisol effects on hormone-sensitive lipase
activates hormone sensitive lipase to hydrolyze triacyl glycerols into glycerol and fatty acids.
when being transported in the blood, fatty acids are bound to
albumin
what organ does beta oxidation take place
liver
most triacylglycerols are SYNTHESIZED by the ___ and transported as _____ to ____ ___ for storage.
most triacylglycerols are SYNTHESIZED by the LIVER and transported as VLDL to ADIPOSE TISSUE for storage.
VLDL (very low density lipoprotein)
____ transport dietary TGAs and cholesterol from intestine to tissues. its assembly occurs in the intestinal lining
chylomicrons
____ transports TGAs from liver to tissues. Where are htey made?
VLDL. made in the liver cells.
____ delivers cholesterol into cells
LDL
___ picks up cholesterol accumulating in blood vessels and delivers cholesterol to liver and steroidgenic tissuesH
HDL
where does de novo cholesterol synthesis occur
in the liver
___ promotes cholesterol synthesis
insulin
main enyzme in cholesterol synthesis? what does it do
lecithin cholesterol acyltransferase. found in the blood stream and activated by HDL apoproteins.
adds a fatty acid to cholesterol, which produces a soluble cholesterylester such as those in HDL.
where does fatty acid synthesis occur
in the liver. then they are stored in adipose tissue. the fatty acids are moved from the liver to the adipose tissue via VLDL
primary end product of fatty acid synthesis
palmitic acid
acetyl coa accumulate in the ___ ___ and is moved to the ____ for fatty acid biosynthesis. How does it do this?
acetyl coa accumulate in the MITOCHONDRIAL MATRIX and is moved to the CYTOSOL for fatty acid biosynthesis.
Moved to the cytosol by first combining with OAA to form citrate, which can freely move across the mitochondrial membrane. in the cytosol, citrate lyase splits citrate back into acetyl coA and OAA.
rate limiting step of fatty acid synthesis.
acetylcoA + CO2 –> malonyl coA via acetyl-coA carbozylase.
this occurs in the cytoplasm.
main reducing agent in fatty acid synthesis
NADPH
beta oxidation occurs in the ___, fatty acid synthesis occurs in the ___
beta oxidation occurs in the MITOCHONDRIA, fatty acid synthesis occurs in the CYTOSOL.
WHAT shuttle is emplyed to bring fatty acids into the mitochondrial matrix for oxidation?
carnitine shuttle. fatty acyl-coA are transported using carnitine shuttle.
what are the products of ONE cycle of beta oxidation
1) acetyl coA - goes to krebs
2) NADH - to ETC
3) FADH - to ETC
FAD, in its fully oxidized form, or quinone form, accepts ____ electrons and ____ protons to become FADH2
FAD, in its fully oxidized form, or quinone form, accepts two electrons and two protons to become FADH2
NAD+, in its fully oxidized form, accepts ___ electrons and ___ to become NADH
a charged hydrogen molecule (H+) and next, two electrons.
4 steps of beta oxidation
1) oxidation of fatty acid to form DB at alpha-beta site. produces FADH
2) hydration of DB to form OH group on beta
3) oxidation of OH gorup to form C=O, forms NADH
4) splitting of betaketoacid into a shorter acyl-coA and acetyl coA. the C=O on the previous beta carbon is now the acyl group of the fatty acid.
for beta oxidation of odd-numbered fatty acids, the last cycle yields ___ acetyl coA and ____ ____ rather than 2 acetyl coA molecules.
for beta oxidation of odd-numbered fatty acids, the last cycle yields ONE acetyl coA and PROPRIONYL-COA rather than 2 acetyl coA molecules.
T/F: ketogenesis can only occur in the liver
FALSE. ketogenesis primarily occurs in the liver, but it cannot be used by the liver.
Though it is the source of ketone bodies, the liver itself cannot use them for energy because it lacks the enzyme thiophorase
where in the cell does ketogenesis occur
mitochondria
name three pancreatic proteases
trypsin, chymptrypsin, caboxypeptidase
is a dipeptidase synthesized in the pancreas?
false. it is a brushboarder enzyme found in the duodenum
how are amino acids and small peptides absorbed in the small intestine
accomplished by secondary active transport linked to sodium. amino acids and sodium in the lumen of the small intestine move into the epithelial cells/brushboarder cells via secondary active transport. in the brushboarder cell, any remaining peptides are broken down into amino acids. at the basal membrane, simple and facilitated diffused transports amino acids into the blood stream.
name the ketogenic amino acids
leucine and lysine. everything else are glucogenic and can be converted to glucose via gluconeogenesis rather than ketone bodies or acetyl coA.
