LIPIDS Flashcards
what are lipids composed of?
carbon, hydrogen, oxygen
what are the major functions of lipids? (rodriguez)
- primary sources of fuel
- provide stability to cell membrane
- sources of hormones
what organ is involved in digestion?
stomach
what organ is involved in absorption?
intestine
what is an example of lipid soluble substance?
vitamins A,D,E,K
lipids can be used to synthesize hormones, for example, steroid hormones. give examples of these steroid hormones
PETA
-progesterone
-estrogen
-testosterone
-androgen
lipids are insoluble in water but soluble in?
organic or nonpolar solvents such as chloroform and ether
lipids, in order to circulate in the blood require special transport mechanism known as?
lipoproteins
give the major lipids in plasma arranges according to its abundance (rodriguez)
PCTFF
1. phospholipids
2. cholesterol
3. triglycerides
4. fatty acids
5. fat soluble vitamins (ADEK)
a lipid consisting of 3 fatty acid molecules joined together with a single glycerol molecule
triglycerides
other term for triglycerides?
triacyl glycerol
this is a lipid that is attached to a phosphate group
phospholipid
a carbon ring structure with functional group alcohol
cholesterol
linear chains of C-H bonds that terminate with a carboxyl group
fatty acids
2 classification of fatty acids
as to chain
as to the number of carbon-to-carbon double bond
classification of fatty acids as to chain
short chain: 4-6 carbon atoms
medium chain: 8-12 carbon atoms
long chain: >12 carbon atoms
classification of fatty acids as to the number of carbon-to-carbon double bond
- saturated f.a
- unsaturated f.a
they provide the substance for conversion to glucose (gluconeogenesis)
fatty acids
saturated fatty acid
no carbon-to-carbon double bond
unsaturated fatty acid
has carbon-to-carbon double bond
one carbon-to-carbon double bond
monounsaturated
two carbon-to-carbon double bond
polyunsaturated
it is a “neutral fat” or “neutral lipid”
triglycerides
why is triglyceride a neutral fat/lipid?
because it does not contain charged groups or polar hydrophilic groups
it is the most common type of fat and main storage lipid in man (adipose tissue)
triglycerides
function of TAG:
when TAG are metabolized, their fatty acids are released into the cells and converted to energy - provides excellent insulation
these facilitates the breakdown of TAG
LEC
- lipoprotein lipase (LPL)
- epinephrine
- cortisol
it allows the body to compactly store long carbon chains for energy that can be used during fasting states and between meals
TAG
TAG from plant sources
polyunsaturated fatty acids and are oils
TAG from animal sources
saturated fatty acids and solid at RT
they are similar in structure with triglycerides except that they only contain 2 fatty acids
phospholipids
3 types/forms of phospholipid
- lecithin / phosphatidylcholine
- sphingomyelin
- cephalin
3 types of cephalin
a. phosphatidyl ethanolamine
b. phosphatidyl serine
c. lysolecithin + inositol phosphatide
-it is the only phospholipid in the membrane that is not derived from glycerol
-it is essential component of cell membrane (RBC and nerve sheath)
sphingomyelin
where is sphingomyelin derived from?
sphingosine (an amino alcohol)
indicator of Niemann-Pick Disease
accumulation of sphingomyelin in liver and spleen
can be used as assessment if infant/fetus can be delivered already
lysolecithin + inositol phosphatide
to where in the forms of phospholipids is normal function of lung correlates strongly?
lecithin:sphingomyelin (L:S) ratio
[>/equal to 2]
- it is an unsaturated steroid cholesterol containing 4 rings (A,B,C,D)
- an amphipathic lipid, found in surface of lipid layers along w/ phospholipids
cholesterol
2 forms of cholesterol
- free cholesterol (unesterified) - 30%
- cholesteryl ester (esterified) - 70%
cholesterol is synthesized in the _____ and is found on the _____
liver ; surface layer of lipoproteins
hormone that promotes transport and excretion of cholesterol?
estrogen
increased cholesterol in the blood
hypercholesterolemia
non-selective increase of fats inside the circulation
hyperlipidemia
true or false
cholesterol serve as a source of fuel
false
it is not readily absorbed by cell, thus, it does not serve as a source of fuel
cholesterol can be converted in the liver to primary bile acids. what are these bile acids?
cholic acid
chenodeoxycholic acid
cholesterol can be converted to steroid hormones. what are these steroid hormones?
glucocorticoids = cortisol
mineralocorticoids = aldosterone, estrogen
cholesterol can be converted to what vitamin?
vitamin D, particularly D3
an active form of vitamin that promotes bone growth esp. in childen
vit. D3
a disease characterized by deficiency of vit. d
rickets
explain how cholesterol is converted to vit. D?
cholesterol -> 7-dehydrocholesterol -> vit. d (by irradation from sunlight)
- it is a form of cholesterol found in plasma & serum
- bound to fatty acid
- undergoes esterification by LCAT
- inactive form; has “protective” property and are stored in cells
cholesteryl ester
- it is a form of cholesterol found in plasma, serum, & RBCs
- a polar non-esterified alcohol
- ACTIVE form of cholesterol w/ CYTOTOXIC PROPERTY
free cholesterol (FC)
a “detoxification step” to reduce the accumulation of free cholesterol
cholesterol esterification
is an enzyme that catalyzes the esterification of cholesterol by promoting transfer of fatty acids from lecithin to cholesterol w/c results in the formation of lysolecithin and cholesterol ester
lecithin-cholesterol acyltransferase (LCAT)
where is LCAT synthesized?
liver
the activator of LCAT?
Apo A-1
it is the removal of ester bond from cholesterol making it a free cholesterol
saponification
lipids in circulation are organized into ____
large lipoprotein particles
what is lipoprotein composed of?
apolipoproteins (proteins and amino acids)
what is found on the surface of lipoprotein?
cholesterol and phospholipid
surface: c,p
what is found on the core of lipoprotein?
cholesteryl ester and TAG
core: c,t
what is the main role of lipoprotein?
delivery of fuel to peripheral cells
what are the major sites for ß-lipoprotein synthesis?
hepatocytes and enterocytes
they deliver lipids to tissues for storage or energy production
beta lipoproteins
what are the major human lipoproteins
-VLDL
-LDL
-HDL
-Chylomicrons
lightest lipoprotein
HDL
heaviest lipoprotein
chylomicrons
most dense lipoprotein
HDL
least dense lipoprotein
chylomicrons
these are large macromolecular complexes of lipids w/ specialized proteins known as apolipoproteins
lipoproteins
lipoprotein that the vit. E depends upon for absorption
chylomicrons
lipoprotein that the vit. E depends upon for delivery to tissues
VLDL & HDL
main purpose of lipoprotein
- to transport TAG and cholesterol to sites of energy storage and utilization
ratio: because these two (tag&chol) travel in plasma not as free-floating molecules but as part of water-soluble complexes called lipoproteins
- help maintain the structural integrity of lipoproteins
- aids in the solubilization of lipids and their transfer from GIT to liver
- present on surface of lpp particles
- serves as ligands for cells receptors
apolipoproteins
apolipoprotein contain this structural motif which shows the ability of proteins to bind to lipids
amphiphatic helix
what are the major apolipoproteins?
Apo A-1
Apo B-48
Apo B-100
- destroys structure of lipoprotein
- catalyzes lysis of lipids bond or covalent bonds that involve lipid
lipoprotein lipase (LPL)
where is the production of chylomicrons
in the intestines from dietary fat
- it is the largest and least dense lipoprotein
- reflect light and account for the turbidity of postprandial plasma
chylomicrons
principal role of chylomicrons
delivery of dietary lipids to hepatic and peripheral cells
major apolipoprotein of chylomicrons?
Apo B-48
what is the hallmark for the presence of chylomicrons in the plasma?
(+) creamy top layer of plasma
VLDL is also known as
pre-beta lipoprotein
where is VLDL produced?
liver
major apolipoprotein of VLDL
Apo B-100 (also contains apo c and e)
- major carriers of endogenous (hepatic-derived) TAGs and transfer TAG from liver to peripheral tissue
- also reflect light and accounts for most of the turbidity observed in fasting hyperlipidimic plasma
VLDL
what causes elevated TAG in the VLDL particles?
prolonged consumption of high fat diet
(-) creamy top layer of plasma
VLDL
ratio: though it also reflects light, they are smaller and less buoyant than chylomicrons = (-) creamy top layer
LDLs are also known as
bad cholesterol
major apolipoprotein of LDL
Apo B-100
where is LDL sythesized?
liver
how is LDL being formed?
they form as a consequence of lipolysis of VLDL
- because they are small, they can infiltrate into the extracellular space of the vessel wall and is taken up by macrophages
HDL
- when macrophages take up too much lipid, they 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
electrophoretic mobility pattern of HDL
alpha lipoprotein
- are the smallest and most dense lipoprotein particle
- exist as either disk-shaped particles or spherical particles
HDL
where is HDL produced/synthesized?
liver and intestine
major apolipoprotein of HDL
Apo A-1
- it is the ability of HDL to remove cholesterol from cells
- is also responsible for the anti-atherogenic property of HDL
reverse cholesterol transport
forms of HDL?
HDL 1, HDL 2, HDL 3
hdl 2 and 3 -> major types
among the major types/forms of HDL, which is
- transports lipids effectively to the liver and is more cardioprotective?
- larger in size and richer in lipid
HDL2
- “sinking pre-beta lipoprotein” bc it has the electrophoretic mobility same as VLDL but density like LDL
- LDL-like particle that contains 1 molecule of apo (a) linked to Apo B-100
- ↑ levels = ↑ risk of premature coronary heart dse and stroke
Lipoprotein (a)
- major end product from the catabolism of VLDL
- constitute about 50% of total LPP in the plasma
- the most cholesterol-rich of the LPP and MOST ATHEROGENIC
- important in assessing px w/ or w/out CHD
- in fasting plasma samples, it contains cholesterol not present in HDL or VLDL
LDL or Beta lipoprotein
- is rich in lipids, primarily free cholesterol and phospholipids
- found in obstructive jaundice and LCAT deficiency
- a specific and sensitive indicator of cholestasis
- contains ApoC and albumin
lipoprotein X (LpX)
- aka “abnormally migrating B-VLDL”
- it has the density of VLDL by ultracentrifugation but migrates w/ LDL in the ß region durIng electrophoresis
- floating beta lipoprotein
- accumulates in type 3 hyperlipoproteinemia or dysbetalipoproteinemia
- also aka “VLDL rich in cholesterol” due to the defective catabolism of VLDL
beta-VLDL
apolipoproteins that are considered differential factors for atherosclerotic disease
ApoA-I and Apo B
apolipoprotein that relates to insulin resistance and increased body fat
ApoA-II
-it is a nonexchangeable apoLPP
-found in VLDL and LDL = may be a predictor of risk to artery dse
ApoB
it is commonly considered as dysfunctional HDL because native HDL is protective of atherosclerosis
oxidized HDL
what are examples of abnormal lipoproteins?
- Lipoprotein X
- ß-VLDL (Floating ß Lipoprotein)
- Oxidized HDL
what are examples of minor lipoproteins?
- intermediate density lipoprotein (IDL)
- lipoprotein (a) / Lp (a)
distinct feature of Lp a
Apo (a), a carbohydrate-rich protein, attached to ApoB-100
- reference method for quantification of lipoproteins
- is based on the CHON and TAG contents of lpp
ultracentrifugation method
most commonly used support medium for electrophoresis
agarose gel
color of lpp in oil red O
red
- Uses polyanions such as heparin sulfate, dextran sulfate, phosphotungstate which react with positive lipoproteins in the presence of divalent cations such as Ca++, Mg++ and Mn++.
POLYANION PRECIPITATION METHODS
Value of HDL that is cardio protective
> 60mg/dl
arrangement of lpp in ultracentrifugation method
Chylomicrons
VLDL (pre-ß-lipoproteins)
LDL (ß-lipoproteins)
HDL (a-lipoproteins))
arrangement of lpp in electrophoresis
from point of origin (-) towards the anode (+):
- Chylomicrons
- LDL (ß-lipoproteins)
- VLDL (pre-ß-lipoproteins)
- HDL (a-lipoproteins)
