Lipids & Lipoproteins Flashcards
they are a rich source of energy and an efficient way for
the body to store excess calories.
Lipids
also precursors for the steroid
hormones, prostaglandins, leukotrienes, and lipoxins.
Lipids
found as a constituent of triglycerides or
phospholipids
Fatty acids
No double bonds
saturated
One double bond
monounsaturated
two or more double bonds
polyunsaturated
The major dietary trans fatty acid is _______, an 18-
carbon fatty acid with one double bond.
elaidic acid
essential fatty acids.
linoleic and
linolenic acids
omega-3, omega-6, and
omega-9 families,
polyunsaturated fatty acids
are precursors for the synthesis of eicosanoids that include prostaglandins,
thromboxanes, prostacyclins, and leukotrienes.
polyunsaturated fatty acids
contain three fatty acid
molecules attached to one molecule of glycerol by ester bonds in one of three
stereochemically distinct bonding positions
triglycerides
Because it is uncharged, triglyceride
is classified as a _____ lipid.
neutral
has a choline head group and is the most common phospholipid found on
lipoproteins and in cell membranes.
Phosphatidylcholine (often referred as lecithin)
the most abundant phospholipids in the body.
phosphatidylcholine and
phosphatidylethanolamine
unsaturated steroid alcohol containing four rings (A, B, C, and
D), and it has a single C–H side chain tail similar to a fatty acid in its physical
properties
Cholesterol
classified as a neutral lipid and are not found on the
surface of lipid layers but instead are located in the center of intracellular lipid
droplets or in the hydrophobic core of lipoproteins, along with triglycerides.
cholesteryl ester
Cholesterol is almost exclusively synthesized by animals, but plants do
contain other sterols (called ______)
phytosterols
Bile acids that promote fat absorption
in the intestine by acting as detergents.
cholic acid and chenodeoxycholic acid,
TRUE/FALSE: The size
of the lipoprotein particle correlates with its core neutral lipid content.
TRUE
Apolipoproteins contain
a structural motif called an _________, which accounts for the
ability of these proteins to bind to lipids.
amphipathic alpha helix
They are the major carriers of endogenous (hepatic-derived)
triglycerides and transfer triglycerides from the liver to peripheral tissue mostly
during the fasting state for energy utilization and storage.
Very-Low-Density Lipoproteins
the delivery of dietary lipids to hepatic and
peripheral cells.
Chylomicrons
referred to as VLDL remnants,
normally only exist transiently during the conversion of VLDL to LDL.
Intermediate-Density Lipoproteins
Macrophages that take
up too much lipid become filled with intracellular lipid drops and turn into _______, which is the predominant cell type of fatty streaks, an early precursor of
atherosclerotic plaques.
foam
cells
They form as a consequence of the
lipolysis of VLDL.
Low-Density Lipoproteins
are LDL-like particles that contain one molecule of apo (a) linked
to apo B-100 by a single disulfide bond.
Lp(a)
TRUE/FALSE: Elevated levels of Lp(a) (>30 mg/dL) are now known to increase the risk of
premature CHD and stroke.
TRUE
Lp(a) particles are heterogeneous in
both size and density, as a result of a differing number of repeating peptide
sequences, called
kringles
can exist as either disk-shaped particles
or, more commonly, spherical particles.
HDL
believed to represent nascent or
newly secreted HDL and is the most active form in removing excess cholesterol
from peripheral cells.
Discoidal HDL
abnormal lipoprotein present in patients with biliary
cirrhosis or cholestasis and in patients with mutations in lecithin–cholesterol
acyltransferase (LCAT), the enzyme that esterifies cholesterol.
Lipoprotein X
a rate-limiting enzyme
in cholesterol biosynthesis.
HMG-CoA reductase
at high doses (~2 to 6 g/d) is also a potent drug for
reducing LDL-C levels (by 5% to 25%) and is the only effective drug at this time
for significantly raising HDL-C levels (by 15% to 35%).
Niacin or nicotinic acid
is a new drug that inhibits the absorption of cholesterol by
inhibiting the Niemann-Pick C1-like 1 (NPC1-L1) transporter in the intestine
without impacting the absorption of fat-soluble nutrients.
Ezetimibe
the lipid abnormality most closely linked to heart
disease.
Hypercholesterolemia
associated with genetic
abnormalities that predispose affected individuals to elevated cholesterol levels,
is called
FH.
The principal route of clearance of circulating LDL-C from the blood is
__________, a process mediated by binding of LDL-C to LDL-R on
the hepatocyte cell membrane.
hepatocyte endocytosis
