BS: Lipids 2 Flashcards
How can lipids be classified?
- according to the presence of an ester bond.
- according to their components
What are the 2 types of lipids under ester classification?
- ester lipids
- non-ester lipids
What are the properties of ester lipids?
- saponifiable lipids
- 1+ ester bond(s)
- undergo hydrolysis
How are ester lipids formed?
they are formed from fatty acids & alcohols combined by an ester linkage.
How can ester lipids be hydrolyzed?
they can be hydrolyzed into smaller lipids via:
- acids
- bases
- enzymes
Can non-ester lipids be hydrolyzed using acids/bases/enzymes?
No, they cannot undergo hydrolysis.
What are the properties of non-ester lipids?
- Non-saponifiable lipids
- No ester bonds
- Don’t undergo hydrolysis
What are examples of ester lipids?
- triacylglycerols
- wax
- phospholipids
- glycolipids
- sphingolipids
What are examples of non-ester lipids?
- free cholestrol
- steroid hormones
- bile acids
- prostaglandins
How are lipids classified according to their components?
- simple lipids
- compound lipids
- derived lipids
What are the components of each type of lipid?
- simple: fatty acid + alcohol only
- compound: fatty acid + alcohol + another component
- derived: formed by hydrolysis of simple or compound lipids
What sets lipids apart from other macromolecules?
unlike proteins, polysaccharides, & nucleic acids, lipids are not polymers.
- they are non-polymeric macromolecules
Types of simple lipids
- TAG
- wax
Types of compound lipids
- phospholipids
- glycolipids
- sulfolipids
- aminolipids
- lipoprotein
types of derived lipids:
steroids
What are fats?
They are one type of lipids that are also called triglycerides.
Define simple lipids
esters of fatty acids with various alcohols
polarity of simple lipids
very non-polar
What are the 2 types of simple lipids?
- TAG
- Wax
properties of TAG
- the alcohol is lower trihydric glycerol
- contains 3 fatty acids
- esters of 3 FAs with glycerol
- found in diet
- found in both solid (fat) & liquid (oil) forms at room temp.
What are examples of TAG?
- butter
- olive oil
What are properties of wax
- alcohol is higher monohydric (ex. cetyl)
- 1 FA
- ester of 1 FA with a higher monohydric alcohol
- cannot be found in diet
- found as solid only at room temp.
What is an example of wax?
bee wax
What are the names/ abbreviations for TAG?
- triacylglycerols (TAG)
- triglyceride (TG)
- neutral fat, uncharged
How are the FAs labelled in TAGs?
they are called R1, R2, & R3.
- they may or may not be the same.
What determines the physical properties (mp) of TAGs?
the fatty acid components
How do the FA components of TAG affect their mp?
- TAG rich in sat, FA are semisolid/solid & called fats. (sat. = fats)
- TAG rich in unsat. FA are liquid & called oils. (unsat. = oils)
What is an example of saturated FA in TAG?
butter; it is solid because it is composed of saturated FA: palmitic & stearic acid.
- butter has a mp of 35.C
Is butter considered healthy & why?
No, it is less healthy becuase it raises levels of cholestrol & TAG in blood.
What is an example of a TAG with unsat. FAs?
olive oil, which is composed of the MUFA, oleic acid.
- mp of 13.C
Is olive oil considered healthy & why?
yes because it lowers the risk of cardiovascular disease & inflammation
What are the functions of TAG?
- most abundant lipid in diet
- most abundant lipid in the body
- storage form of lipids
- source of energy
What are esters of 1 FA with glycerol called?
MAG
What is DAG?
esters of 2 FAs with glycerol
What is wax?
it is aka biological wax
What is the alcohol in wax?
- higher weight
- long-chain (C16-C30)
- monohydric alcohols
what are examples of alcohols in wax?
- cetyl
- triacontanol
What are the fatty acids in wax?
- also long-chain (C14-C36)
- can be SFA or UFA
What are the physical properties (mp) of wax?
they are solids, since their FA chain is so long
What is beeswax?
- solid
- composed of triacontanoylpalmitate.
- beeswax has a high mp of about 60 to 100.C
- it is used in honeycomb construction
What are compound lipids?
aka complex lipids, are essentially a simple lipid with another group.
they are also known as membrane lipids since they are found in the cell membrane
What are the 5 examples of compound lipids?
recall!
- phospholipids
- glycolipids
- sulfolipids
- aminolipids
- lipoproteins
What are some membrane lipids and their properties?
- phospholipids
- glycolipids
- sterol
these lipids are all amphipathic.
What is the composition of phospholipids?
- Fatty acids + alcohol + phosphoric acid
- simple lipid & phosphate (anion)
- phospholipids contain a phosphoric acid residue
What is the solubility of phospholipids?
amphipathic: polar head & 2 nonpolar tails.
- phosphate attaches the hydrophobic region to the polar group.
What is the function of phospholipids?
- they are the main lipid constituent of membranes
- polar heads on outer surfaces
- nonpolar tails in between bilayer.
What are the 2 types of phospholipids?
- glycerophospholipids
- sphingophospholipids
these are classified according to the alcohol.
What are the properties of glycerophospholipids?
- aka glycerophosphatides
- phosphoglycerides
- alcohol/backbone is glycerol
- FA + glycerol + phosphate + alcohol
What are the properties of sphingophospholipids?
- sphingophosphatides
- phosphosphingosides
- alcohol/ backbone is sphingosine
- FA + sphingosine + phosphate
What is an example of sphingophospholipids?
Sphingomyelin
type of phospholipids
What are glycerophospholipids?
- a major lipid component of biological membranes
- amphiphilic molecules
- nonpolar aliphatic tails
- polar phosphoryl-X heads
- have 2 FAs attached via ester linkage to C1 & C2 of glycerol
- have a highly polar/ charged group attached by phosphodiester to C3
- are/ contain derivatives from phosphatidic acid (PA)
What is phosphatidic acid?
Glycerol + 2 FA + Phosphate (phosphomonoester)
What is the full systematic name of phosphatidic acid?
1,2-diacyl-sn glycero-3-phosphate
How is it composed?
It is a glycerol backbone with esterified FAs at sn-1 & sn-2, the phosphate head esterified at sn-3.
So i.e. what are the components of phosphatidic acid?
DAG with phosphate on C3
polar head (x): H
Is there an alcohol in the head of phosphatidic acid?
The phosphate head of phosphatidic acid contains OH, which would be classified as the alcohol. However, the other more complex glycerophospholipids would contain larger alcohol groups as they are derivates of phosphatidic acid where the H is replaced by an alcohol.
What is the function of phosphatidic acid (PA)?
- the simplest glycerophospholipid
- the precursor parent (backbone) of glycerophospholipids
- an intermediate in the biosynthesis of triglycerides & other phospho-glycerides
What are all the examples of ester-linked glycerophospholipids mentioned?
- phosphatidic acid
- phosphatidyl serine
- phosphatidyl ethanolamine (cephalin)
- phosphatidyl choline (lecithin)
- phosphatidyl inositol (lipositol)
- phosphatidyl glycerol
- diphosphatidyl glycerol (cardiolipins)
What are some common membrane lipids?
- phosphatidic acid
- phosphatidyl-choline
- phosphatidyl-ethanolamine
- phosphatidyl- serine
What are all the examples of ether-linked glycerophospholipids mentioned?
- plasmalogen
- platelet-activating factor
What is plasmalogen?
- ether-linked alkene
- an enol from ether-linked fatty alcohol in C1
- polar head X group is either ethanolamine or choline, but is often ethanolamine.
- this ether-linked glycerophospholipid is commonly found in the cardiovascular system & nervous system
What disease is plasmalogen often associated with?
reduced levels of plasmolagen in brain tissue is associated with Alzheimer’s Disease
What is platelet-activating factor?
- X group is choline
- an compound that is released from leukocytes (basophils)
What functions does PAF have?
- stimulates platelet aggregation
- stimulates release of serotonin
How prevalent are plasmalogens in heart tissue?
around 50% of phospholipids in the heart are plasmalogens.
Which ether-linked phosphoglyceride is an unsaturated alkene?
plasmalogen
Which ether-linked phosphoglyceride is a saturated alkyl?
PAF; it is a plasmalogen but with an ether-linked alkane.
What are the components of sphingomyelin?
sphingosine + 1 FA + phosphate + choline/ethanolamine
(phosphorylcholine head)
sphingosine & 1 FA = ceramide
What is sphingomyelin?
- aka sphingol/sphingoid base
- an amphoteric lipid that contains phosphocholine or phosphoethanolamine at the polar group
- long unsaturated alcohol amine that contains OH & NH2
- 18 carbon amino alcohol with a trans double bond
- it is the backbone of all sphingolipids
- sphingolipids can either be be sphingophospholipids or sphingoglycolipids
- all sphingolipids have a polar head & non-polar tail & are major membrane components.
- sphingosine is chemically 2-amino-4-trans-octadecene-1,3-diol
N-acyl fatty acid derivatives of sphingosine are known as ceramides.
- parent compounds of sphingolipids
- if X is H, then compound is ceramide.
What type of FA is connected to sphingosine in ceramides?
Either saturated FAs or mono-unsat. FAs.
What are the components of ceramide?
sphingosine + fatty acid
- F.A. is anywhere from 14 to 26 carbon long (long)
What if the ceramide is longer than 26 carbons?
This is a ceramide that is commonly found on the surface of special skin.
What is the function of sphingomyelin?
- most abundant complex sphingolipid in human cells
- found in the myelin sheets of N.S
What are the components of glycolipids?
Fatty acids + sphingosine + sugar (carbohydrate)
so it is:
ceramide & sugar; monosaccharide or oligosaccharide
- they are sphingolipids with a carbohydrate attached to sphingoid backbone by a glycosidic bond.
What is the solubility of glycolipids?
- amphipathic; polar head & non-polar tail
- the polar group is a sugar
What is the function of glycolipids?
- maintains cell membrane stability & facilitate cell recognition
- critical for immune response & communications that allow cells to connect to each other to form tissues.
Where are glycolipids found?
- found on the surface of all eukaryotic cell membranes
- only 5% of lipids in cell membranes are glycolipids
- occur in outer layer of cell membrane & extend from PL bilayer into extracellular part.
What are the 2 types of glycolipids?
- simple glycolipids
- complex glycolipids
What are the properties of simple glycolipids?
with examples
- neutral; don’t contain acid group
- FA + sphingosine + sugar only
- simple glycolipids: cerebroside & globoside
What are the properties of complex glycolipids?
- charged; contain an acid group
- FA + sphingosine + sugar + acid
- examples: gangliosides & sulfitide
What are cerebrosides?
- they are the simplest glycolipid
- ceramide + monosaccharide
- contains a single sugar residue linked to ceramide
- the monosaccharide is joined to the OH of ceramide at C1 by a glycosidic bond
- includes: glucosylcerebroside & galactosylcerebroside
Where are cerebrosides found & what is its function?
- primarily in the brain & P.N.S. tissue
- insulator & protective coat to nerve cells
- forms outer layer of plasma membrane
- in neural tissue: galactose is present in plasma membrane due to it
- non-neuronal tissue: glucose is in plasma membrane [liver, lung, spleen]
What are globosides?
- cerebrocides with di, tri, or tetrasaccharide
- includes lactosylcerebroside
complex glycolipids
What are gangliosides?
- negatively charged at pH 7.0
- contains sialic acid [NANA]
- the most complex glycolipid
- ceramide + oligosaccharide + NANA
- contains a number of sugar residues linked to ceramide & salic acid
- complex oligosaccharide is joined to OH of ceramide at C1 via a glycosidic bond
What complex oligosaccharides are found in gangliosides?
- glucose
- galactose
- NAGLA
Where are gangliosides found?
- main component of animal cell membrane
- found in plasma membrane of neuron
- found in ganglion cells of PNS tissue
- present in spleen & RBC
Define lipoprotein
round particle made of lipids & proteins that travel in the bloodstream to cells.
What are the components of lipoproteins?
- Lipid + Protein
- TAG & cholestrol are the 2 types of lipids in lipoprotein
- cholestrol moves throughout the body carried by lipoproteins in the blood
What are the 5 types of lipoproteins?
- chylomicron (CM)
- very low density lipoprotein (vLDL)
- intermediate density lipoprotein (IDL)
- low density lipoprotein (LDL)
- high density lipoprotein (HDL)
What is the function of chylomicrons (CM)?
transports exogenous TAG from intestine to tissue
What is the function of vLDL?
transports endogenous TAG from liver to tissue
What is the function of LDL?
transports cholestrol from liver to tissue
- this cholestrol is considered BAD
what is the function of HDL?
reverse transports cholestrol from tissue to liver
this is considered good cholestrol
