Lipid Structures & Theory Flashcards
(47 cards)
Palmitic Acid
CH3–(CH2)14–COOH
most common saturated fatty acid in nature
Stearic Acid
CH3–(CH2)16–COOH
Palmitoleic Acid
9-C16:1
omega-7
Oleic Acid
- main constituent of olive oil
9-C18:1
omega-9
Linoleic Acid
9,12-C18:2
omega-6 polyunsaturated
Linolenic Acid
specifically alpha-linolenic, the omega-3 version
9,12,15-C18:3
Arachidonic Acid
importance?
5,8,11,14-C20:4
omega-6 polyunsaturated
- very important as a signaling molecule > creates prostaglandins, thromboxanes, and leukotrienes
In general, what is a lipid?
organic molecules containing fatty acids or a steroid nucleus
What are the 4 types of lipids that contain fatty acids?
- Waxes
- Triacylgycerols
- Glycerophospholipids
- Prostaglandins
Describe what can be assumed about a lipid structure from its name using eicosapentaenoic acid as an example.
**eicosa **- denotes 20 carbons total
penta-enoic - denotes 5 “-enes” or double bonds
- no information about the location of the double bonds is given here, but would be indicated with numbers preceding the name
How can double bonds’ locations be specified in a prefix of a fatty acid name?
(Δn)
so an FA with double bonds at carbons 5, 8, and 11 (starting from the COOH end) would contain the prefix:
(Δ5,8,11)
What is the general strucuture of a triglyceride?
- a glycerol with three fatty acids replacing the Hs of its 3 hydroxyl groups
- the H of the FAs carboxyl is also removed to bind with glycerol
- the binding of the FA carboxyl to the glycerol hydroxyl forms an ester bond
(an ester is a central carbon double bonded to an oxygen and single bonded to an R group and another oxygen with a second R group)
What is the general structure of a diglyceride (AKA diacylglycerol)?
Same as a triglyceride, but one of the glycerol’s hydroxyls remains unchanged
What is an ester bond?
- formed between COOH and OH groups
C double bonded to O, single bonded to R1 and OR2
What are prostaglandins?
- eicosanoic signaling lipids derived from arachidonic acid via COX enzymes
- regulate inflammation, among many other functions
- formed by creation of 5-C ring in middle of 20-C chain (on C-8 and 12)
- targeted by NSAIDs (COX inhibitors)
- include prostacyclins (prostaglandin I2) which inhibits platelet activation and vasodilates
What are thromboxanes?
- eicosanoid derivatives of prostaglandins
- 6C ring with ether (R-O-R’)
- vasoconstrictive, hypertensive platelet-aggregating agent
What are leukotrienes?
- eicosanoid inflammatory mediators
- first found in leukocytes, but produced in many immune cells
- trigger contractions in bronchiole smooth muscle, thus influence asthma and allergies
- contain no ring, but have epoxide (a 3 atom ring with O)
What are the 3 important eicosanoid groups to know?
- prostaglandins
- thromboxanes
- leukotrienes
if a fatty acid is named “omega-n”, what does this indicate?
- the n is a number which indicates how far from the methyl carbon (AKA omega carbon) a double bond is found
- this is determined by starting with the omega carbon as #1
example: omega-3 fatty acids have a double bond starting from the 3rd carbon
What are the functions of triacylglycerols?
- energy storage
- thermal insulation
- mechanical protection
(within adipocytes)
Where is the energy in triacylglycerols that is used metabolically to produce ATP?
- in the long chains of fatty acids containing many hydrogens
- hydrogens are “burned” with O2in mitochondria to form water and drive the process of oxidative phosphorylation
How much energy do fatty acids have in comparison to carbohydrates?
Why?
approx. 2x the energy per unit mass
b/C both Hs connected to a fatty acid chain are reduced
ex:
FA = H-C-H
but
Carb = H-C-OH
What are waxes?
How do their physical properties differ from other lipids?
Where are they in the body?
- simple esters of long fatty acids (-COOH) and long alcohols (-OH)
- have higher melting points
- make up hydrophobic coatings on skin and in ears, prevent maceration of fetus within womb
What are glycerophospholipids?
Why is the phosphate specifically located on a certain carbon of the backbone?
- main compononents of biological membranes
- glycerol with 2 FAs and phosphate on C3
- glycerol-3-phosphate not 1, because glycerol is prochiral
