Lipids Flashcards
Phospholipids Components
Fatty acid units, Amino alcohol unit, Phosphoric acid unit, Glycerol Unit
Simplest Phosphoglyceride
phosphotidate
Complex Phosphoglyceride
phosphoryl group + hydrophobic molecules, ie chloine/ ethanolamine
Melting of fatty acids
- increases with increasing chain length because long hydrocarbon chains interact more strongly than short ones
- lowered with increasing unsaturation, fatty acids with trans double bonds pack more tightly
Lipids polarity
non-polar
Types of lipids
Simple, complex & derived
Simple lipids
ester-containing lipids with only 2 types of components: alcohol & =>1 fatty acids
Complex lipids
ester-containing lipids with >2 types of components: alcohol, fatty acids & other components
Derived lipids (non-saponifiable)
formed by metabolic transformation of fatty acids, derived from simple and complex lipids via hydrolysis
Lipids definition
lipids are esters formed via the combination of fatty acids with an alcohol called glycerol
Fatty acids
straight-chain organic acids consisting of hydrocarbon (CH) chain with a terminal carboxyl (-COOH) group
Glycerol Definition
A triol. Is an alcohol containing 3 hydroxyl (-OH) groups (alcohol), each of which can be esterified with a fatty acid.
What are neutral acylglycerols
ester of glycogen and fatty acids that occur naturally as fats and oils
Glycerol components
A trihydric alcohol, containing primary and secondary alcohol groups
Types of acylglycerols
- Monoacylglycerol
- Diacylglycerol
- Triacylglycerol (aka Triglyceride)
Monoacylglycerol components
1 fatty acids and 2 hydroxyls (OH)
Diacylglycerol components
2 fatty acids and 1 hydroxyl
Triacylglycerol components
3 Fatty acids
Fatty acids in simple lipids (pt. 1)
- long-chain carboxyl acids
- fat characteristics determined by kinds and proportions of fatty acids found in acylglycerols (non-polar), and arrangement on the glycerol molecule
Fatty acids in simple lipids (pt. 2)
- found in natural fats contains even no. of C atoms
- free FA are rare in nature
Fatty acid structure
- Long-chain monocarboxylic acids
- CH3(CH2)nCOOH
- Size range: C4-C36. In nature, C12-C24
- Always even no. of C
Amphiphilic molecule (fatty acids)
- hydrophilic and hydrophobic
- hydrocarbon (CH) group (non-polar)
- COOH group (polar)
Saturated & Unsaturated
Saturated: no double bonds
Unsaturated: one or more double bonds
Saturated fatty acid general formula
CH3(CH2)nCOOH
Saturated fatty acid general formula
CH3(CH2)nCOOH
Unsaturated fatty acid general formula
CH3(CH2)nCH=CH(CH2)nCOOH
Type of unsaturated double bond
- mono-unsaturated
- poly-unsaturated
- conjugated and non-conjugated
Types of essential fatty acids
- Linoleic and Linolenic (Omega 3 and Omega 6)
- found in plants and fish oils
- produce hormone-like substances to regulate body functions (etc. blood pressure & blood clotting)
Saturated Fatty Acid reactions
- esterification
- hydrolysis
- acid-base (neutralization)
Unsaturated Fatty Acid Reactions
- esterification
- hydrolysis
- acid-base (neutralization)
- addition (hydrogenation)
Esterification of Fatty Acid
- 1 Glycerol + 1 FA = monoglyceride + water
- 1 Monoglyceride + 1 FA = Diglyceride + water
- 1 Diglyceride + 1 FA = triglyceride + water
Formation of triglyceride
- esterification of glycerol and fatty acids (same as lipids)
- simple triglyceride is formed in complete esterification when only one fatty acid used
- =>2 fatty acids = mixed triglyceride
- simple triglycerides are rare, and can form optical isomers
Complex phospholipids
- cellular membranes are primarily made of complex lipids
- Two categories of complex lipids: phospholipids and glycolipids
- Two major components of phospholipids found in cell membranes are phosphoglycerides and sphingolipids
complex lipids structure (Phosphoglyceride)
- derived from glycerol
- also known as glycerophospholipids
- complex lipids containing glycerol, two fatty acids, & a phosphoric acid attached to another N- containing group
- referred to as phospholipids
complex lipids structure (Phosphoglyceride)
- derived from glycerol
- also known as glycerophospholipids
- complex lipids containing glycerol, two fatty acids, & a phosphoric acid attached to another N- containing group
- referred to as phospholipids
Modified Fat
phosphate replaces one fatty acid chain
Glycolipid Uses
- Production of cell membranes
- Emulsifying agents
Chemical Properties of fats & oils (Melting Point)
- food-related (solidification)
- most fats are solid at r.t
- Melt gradually or in staged due to different types of triglyceride molecules
Physical Properties of fats & oils (Solubility)
- solubility of fats decreases with increasing chain length
- phospholipids & glycolipid molecules are more soluble in polar solvent than triglyceride
Physical Properties of fats & oils (Specific Gravity)
- Specific Gravity less than 1 (0.9)
- Specific Gravity increases with decreasing molecular weight and increasing unsaturation
Physical Properties of fats & oils (Colour)
- Pure fats/oils are white or yellow solids/liquids
- odourless and tasteless
Chemical properties of fats & oils (Saponificaiton)
- Heating of fat with a strong base (etc NaOH) to produce glycerol and salt of fatty acid
- sodium/ potassium salt of fatty acid is soap
- Long-chain aliphatic part (non polar, hydrophobic), carboxylate part (polar, hydrophilic)
- emulsifies grease for easier removal
- lowers surface tension of water easier emulsification
Soap Molecule distinct parts
hydrophilic & hydrophobic
Types of fats & oil rancidity
- hydrolytic rancidity
- Oxidative rancidity
Hydrolytic Rancidity
- From exposure to moist air
- Microbes in air contain enzymes lipases to catalyze hydrolysis
Oxidative Rancidity
- From oxidation of double bonds in unsaturated fatty acids
- Double bonds rupture to form pungent & volatile aldehydes
Steroids
-Broad class of compounds that have the same base structure
Cholesterol (Steroid)
- Principal membrane lipid for fluidity
- Amphiphilic: polar OH groups & extensive non-polar fused rings & hydrocarbon chains
Lipoprotein
-function to transport cholesterol to peripheral tissues
