MMT: Lipids I and II Flashcards
Define the term lipid in terms of their basic properties
molecules that are insoluble in aqueous solutions and soluble in nonpolar solvents
State the major roles of biological lipids
storage form of energy (triacylglycerols), structural component of membranes, serve as vitamins and hormones, serve as cofactors
List the five common types of lipids
- fatty acids
- acylglycerols
- phosphoacylglycerols
- shingolipids
- steroids
Describe the common features of fatty acids
- hydrocarbon chains with a carboxylic acid group at one end (negative charge at physiological pH).
- in animals, the carbon chains are unbranched.
- double bonds are in cis configuration
- double bonds are unconjugated, aka separated by methylene groups
Explain the difference between saturated and unsaturated fatty acids
saturated: fully saturated with hydrogens; no double bonds. short chains (8C) are liquid at room temperature, while longer chains are solid at room temperature. most of the saturated chains are longer, so they’re usually solid at room temperature and increase rigidity.
unsaturated: not saturated with hydrogens, so double bonds are seen. the double bonds lower the melting point and allow for more fluidity
describe the nomenclature sytems for unsaturated fatty acids
- systematic nomenclature system: carbon #1 at the carboxyl. number of carbons: number of sites of unsaturation. anoic acid means no double bonds, enoic acid means one double bond, dienoic acid means two double bonds. ex: octadecadienoic acid (C18:2) means 18 carbons and 2 double bonds
- deltaX system: systematic nomenclature with the addition of the location of the double bond. starting from c1 at the carboxyl, count until reaching the bond. formate is Cy:z deltaX, with y being number of carbons, z being number of double bonds, and x being the carbon number where the double bond begins. name all double bonds in the structure.
- omega nomenclature: deltaX system with the addition of omega counting. counting from the terminal methyl group (omega carbon) to the first carbon in the double bond. format is Cy:z omegaW deltaX, with y being number of carbons, z being number of double bonds, x being the carbon number where the double bond begins counting from the carboxyl, and W being the carbon number where the double bond begins counting from the omega carbon. for omega, only count the first encountered bond if there’s more than one.
describe the nomenclature system for saturated fatty acids
systematic nomenclature system: carbon #1 at the carboxyl, terminal methyl group is the omega carbon. number of carbons: number of sites of unsaturation. ex: Octanoic acid C8:0 has 8 carbons and no double bonds
Distinguish between cis- and trans- double bonds in unsaturated fatty acids
cis bonds tend to occur more in nature. these bonds create a kink, while trans look like a traditional hydrocarbon chain. unsaturated fatty acids with cis configuration tend to be liquid at room temperature.
the trans unsaturated fatty acids are created by partial hydrogenation of cis fatty acids and tend to be used in the restaurant industry to increase shelf life; they’re solid at room temperature.
List the four unsaturated fatty acid families and indicate which ones are essential
- palmitoleic
- oleic
- linoleic (essential)
- alpha-linoleic (essential)
why are trans unsaturated fatty acids an issue?
since our bodies are euipped to deal with primarily cis unsaturated fatty acids, trans unsaturated fatty acids in large amounts obtained from food pose an issue as our body does not have a good way to break them down. as such, they accumulate in our system and lead to things like heart disease.
State several major benefits of including long-chain omega-3 fatty acids in the diet.
preventing arythmia, atheroscleorisis, alzheimers. help with blood clotting and immune regulation.
State the general outcomes of essential fatty acid deficiency
lowered immune system and lowered health in general!
Describe the common features of acylglycerols and phosphoacylglycerols
both have a glycerol backbone and fatty acids attached, but acylglycerols have 3 fatty acids attached while phosphoacylglycerols have 2 fatty acids and one phosphate group
List different types of phosphoacyglycerols
PS, PE, PC, PI, PA
connection: PC and PS are common outside membrane, PA, PI, PE inside!
Describe the role of dipalmitoyl phosphatidylcholine in respiratory distress syndrome (RDS)
dipalmitoyl phosphatidylcholine is a major component of lung surfactant, which is required to help keep the lungs inflated by decreasing surface tension. premature babies don’t create dipalmitoyl phosphatidylcholine, reducing secretion of lung surfactant and leading to the potential collapse of the lungs
name key signs of respiratory distress syndrome
- retraction of the chest
- nasal flaring
- tachypnea (RR>60)
- tachycardia (HR>160)
- grunting
- cyanosis
how do we treat RDS
lung surfactant from cow lungs; their protein components are similar to ours so their surfactant works well
Describe the common features of sphingolipids
they contain a sphingosine backbone made from palmitoyl CoA and serine, and a reactive hydroxyl and amino group at the polar end
ceramide: structural and functional features
sphingosine (palmitoyl CoA and serine) with the addition of a fatty acyl CoA via amide linkage.
sphingomyelin: structural and functional features
sphingosine backbone, fatty acid, and phosphocholine. component of myelin sheaths
cerebroside: structural and functional features
a glycosphingolipid with sphingosine, fatty acid, and glucose or galactose. primarily found in the brain
globoside: structural and functional features
a glycosphingolipid with sphingosine, fatty acid, and more than one sugar unit. important in the nervous system
sulfatide: structural and functional features
a glycosphingolipid with sphingosine, fatty acid, and galactose linked to sulfate. important in the nervous system
ganglioside: structural and functional features
a glycosphingolipid with sphingosine, fatty acid, and an oligosaccharide chain containing saliac acid (negative charge). important in the nervous system
Describe the functional roles of sphingosine, S1P, ceramide and C1P
- ceramide: makes other sphingolipids; can be activated and lead to signaling processes
Distinguish between a ganglioside and a neutral (non-charged) glycosphingolipid
gangliosides have a negative charge due to sialic acid (NANA) residues. as a result, they can interact with hormone receptors and form ionic interactions on the surface of the plasma membrane.
Define gangliosidoses
lysosomal storage diseases associated with defective enzymes that process gangliosides. this causes the accumulation of gangliosides and causes cell damage.
Tay-Sachs disease: cause/enzyme involved and symptoms
a gangliosidosis condition in which GM2 accumulates due to deficient hexosaminidase. symptoms include mental delays, cherry red spots on retina, and psychomotor dysfunction.
steroid molecules: basic structure, what they’re synthesized from, and what they’re invovled in
contain a four-ring structure called the steroid nucleus and are synthesized from acetyl-CoA. they stabilize cell membranes, are a component of bile salts, and are a precurser to steroid hormones
Specify the functional roles and derivatives of cholesterol
Contrast free and esterified cholesterol
esterified cholesterol occurs when cholesterol reacts with a fatty acyl chain, and the two are connected by an ester linkage. they’re extremely hydrophobic and are found in lipoprotein particles. free cholesterol has a hydrophilic portion, but the hydrophilic region is used to link the cholesterol to the fatty acyl, taking it out of commission.
give the structure for palmitic acid
C16:0 hexadeconate
give the structure for linoleic aid
C18:2 omega6 (delta 9,12- octadecadienoate)
give the structure for a-linoleic acid
C18:3 omega3 (delta 9,12,15- octadecatrienoate)
arachidonic acid is derived from ___ via…
linoleic acid by modifying the fatty acid chain closest to the carboxyl group, less than delta 9
give the general structure of acylglycerols
glycerol backbone that can link 1-3 fatty acids via ester linkage. theyre water soluble and are a large storage form of energy (triacylglycerols)
give the general structure of phosphoacylglycerols
contain a glycerol backbone, two fatty acids linked, and a phosphate group linked. they are a major component of our membranes, as they are amphipathic!
