Lipid Metabolism Flashcards
What is the structure of a saturated fatty acid?
No double bonds (palmitic or stearic acid) and
What does an omega carbon mean?
last carbon of the chain (furthest from the carboxyl group)
What is the structure of a unsaturated fatty acid, a monosaturated fatty acid and a polysaccharide fatty acid?
unsaturated has double bond
mono= one double bond
poly= 2+ double bond
What does the first number and the numbers in the super script after the delta in a fatty acid chain mean?
first: how many carbons
after delta: where double bonds are
What are the essential fatty acids?
linoleic acid
l-linolenic acid
arachidonic acid
insufficient amounts of the essential fatty acids can lead to
skin and kidney damage, cataracts, increased membrane permeability to water
virtually all the naturally occurring double bonds are
in cis configuration
w-6 20:4 is what fatty acid?
arachidonic
what is the major precursor to eicosanoids?
essential fatty acids, arachidonic acid
linoleic acid
l-linolenic acid
What is thromboxane’s needed for?
platelet aggregation
what is an eicosanoid?
prostaglandins, thromboxanes, and leukotrienes
What does eicosanoids regulate?
inflammatory response
– muscle contraction
– blood pressure
– bronchodilation
– bronchoconstriction
– water/sodium excretion
what does phosspholipase A2 do?
cleaves ester bond in second fatty acid
Where can trans fatty acids be found in the diet?
in processed foods
How are trans fatty acids formed?
induced to foods by hydrogenation (adding H to a double bond making it go from cis to trans, giving it a more liquid like structure)
Trans fatty acids increase ____
serum LDL cholesterol, triacylglycerol’s, platelet aggregation
What are cis double bonds role in the lipid bilayer?
make the membrane loosely packed which is important for proper fluidity and function of receptors and membrane proteins to function)
What does a trans double bond do to the lipid bilayer?
make the packing much tighter (decreases fluidity which can impair the function of membrane proteins and receptors)
What does trans fatty acids decease?
HDL cholesterol
What can trans fatty acids lead to? (due to the things they increase and decrease)
growth halt in new borns
What food is rich in omega 3 FA and what positve effect do these FA have?
fish oils and eggs
they decrease cardiovascular mortality
Where are acylglycerols stored?
adipose tissue
What are abundant lipids in mammalian cell membranes?
phosphoacylglycerols, sphingolipids, and cholesterol
What is the structure of a Phosphoacylglycerols?
● Glycerol backbone
● Fatty acids are linked to
C1 and C2 of the glycerol
backbone.
● The fatty acyl chains have
varying numbers of carbons
and double bonds.
● All of them have a
phosphate moiety (P) linking
to C3 of the glycerol
backbone and then a head group can bond to that
If only a phosphate group is attached to C3 of the glycerol
backbone, the lipid is called ______.
phosphatidic acid (PA)
If a choline group is attached to the phosphate, the compound is
called ________
phosphatidylcholine (PC)
What is the importance of the charge of the amine group of phosphatidylcholine and the phosphate group?
gives a local negative charge (these are important at the surface of membranes)
Phosphatidylcholine is also called _______
lecithin
Phosphatidylethanolamine (PE) has what head group?
2C and1 N
What is lysolecithin?
FA with one FA chain associated
Phosphatidylinositol 4,5-
bisphosphate (PIP2) is important for what?
signal transduction (some can have neg charge, some no charge)
What role does phosphoacylglycerol play in the lungs?
surfactant
What are some key functions of Phosphoacylglycerols?
– key components of cell membranes
– playing a pivotal role in signal transduction and
metabolic pathways
– a major determinant of cell membrane fluidity and
membrane lateral organization, thus regulating cell
membrane functions
What is the structure of sphingolipids?
–Sphingosine backbone (18 carbons) of sphingolipids.
–Sphingosine is part of ceramide.
–The first C on sphingosine is linked to a phosphate (for sphingomyelin) or a sugar (for sphingoglycolipid) moiety.
–The second C (C2) is linked to an amino group.
–C3 is linked to a hydrocarbon chain
What are the two groups of sphingolipids?
sphingomyelin and sphingoglycolipid
What is the difference between a sphingomyelin and sphingoglycolipid?
Sphingomyelin: first C on phosphate
Sphingoglycolipid: first C on sugar
All sphingolipids are derivatives of _______
ceramide
When galactose is linked to –OH
on C1 oh a ceramide, it is
galactocerebroside
When phosphorylcholine is linked to –OH on C1 of ceramide, the compound is called
______
sphingomyelin
When an oligosaccharide is
linked to –OH on C1 on a ceramide, it is called
ganglioside
NANA = ______________;
GalNAc = _______________
N-acetylneuraminic acid
N-acetylgalactosamine
What is sphingolipids role biologically?
– key components of cell membranes (particularly abundant in nerve cell membranes)
– regulators in cell death/survival, toxin binding, and cell-cell recognition
Cholesterol structure:
* Cholesterol is very _________and contains a tatracyclic ring
* Humans do not have
____ to degrade this ring
structure.
non-polar (not soluble in water)
enzymes
Cholesterol is a major component in cell membranes, but________ are not
embedded in the membranes. They are located inside the cell as part of oily droplets or they are located in blood lipoprotein particles
cholesterol esters
What is Sphingosine 1-phosphate (S1P)?
Sphingosine 1-phosphate (S1P): an intracellular second
messenger and an extracellular mediator. It plays an
important role in signaling pathways. It stimulates cell
proliferation and survival, and regulates cell motility and
cytoskeletal reorganization
Ceraminde is also a regulator of:
cell death
Free cholesterol can be converted to
cholesterol esters
does cholesterol make lipid bilayers?
no but it can insert itself into bilayers formed by sphingolipids and phosphoacylglycerols
What is the key takeaway of sphingolipid metabolites?
degradations products are important in signaling and cell functions
in the cell membrane carbohydrate moieties residing in the ________ side
extracellular
Dietary TGs can be digested by
______ produced by glands
in the tongue and soft palate
lingual lipase
Dietary TGs can also be digested
by _____ produced in the
stomach
gastric lipase
The function of the co-lipase is to:
attract and anchor
the pancreatic lipase to
the surface of the emulsion particles
90% of dietary lipids are ____
Triacylglycerols
What is the difference between bile acids and bile salts?
bile acids are protonated
the deprotonated form is what has detergent properties and is needed for lipid emulsion
What is the structure of a emulsion particle and mixed micelle?
non polar core lipids (TGs)
polar surface lipids
Digestion of dietaryTGs in the small intestine requires:
Pancreatic lipase
Bile salts
Co-lipase
Bicarbonate
Bile ____ is more common at physiological pH
salt (anionic form)
Bile Salts are used to make ____
emulsion particles
What is bicarbonates role in lipid absorption in the small intestine
raise pH to increase number of anionic species which drives lipid digestion and absorption
How are the 2MG and FA taken up by intestinal epithelial cells?
they are hydrophobic so they need to be take up by a micelle (once taken up its a mixed micelle) to be transported out of the lumen of SI
In the small intestine, dietary TGs are hydrolyzed to what products?
2-monoacylglycerol
(2-MG) and fatty acids (FA)
Bicarbonates effect in enzymes is…
changes the pH making the enzymes as active as possible
What happens once the mixed micelle crosses the epithelium of the SI?
the 2MG and FA are release from the micelle and can reform the TG
What can happen once the TGs are reformed in the epithelium?
combine with other
lipid-soluble materials and apo-proteins to form chylomicrons and can be taken to lymph then blood (fat soluble vitamins and essential fatty acids can be taken up same way)
What is lipid malabsorption?
Inability to digest triacylglycerols (TGs) due to pancreatic lipase or bile acid deficiencies
Lipid malabsorption causes
steatorrhea
What can steatorrhea lead to?
leading to a loss of important energy fuels, severe weight loss, and vitamin (fat-soluble vitamins, A, D, E, and K) as well as essential fatty acid and caloric deficiencies
If you have a problem secreting bile salts what health issue could occur?
deficiency of essential fatty acids, fat soluble vitamins and TGs
Acyl Co A has ____ carbons in the fatty acyl chain
2
What is the starting material for fatty acid synthesis?
acetyl coA
What is the most abundant FA in the body?
palmitate
Why do you have to go through the mitochondria to make acetyl co A
because you need pyruvate dehydrogenase which is in the mitochondria
the rxn catalyzed by pyruvate dehydrogenase has what properties?
large negitive delta G
makes it irreversible
Can you make acetyl co A from pyruvate?
no
Describe the structure of acetyl coA, what effect does its structure have?
big and very negative (4 negative charges), it cant pass through the mitochondria, must be converted to citrate, then it can pass
