BIOCHEM WEEK 4 Flashcards
• Fats
• Insoluble in water
• Soluble in nonpolar organic solvents
• Wide structural diversity
• Can be classified based on biochemical function
Lipids
Classification of Lipids
BASED ON FUNCTION
• triacylglycerols
Energy storage
Classification of Lipids
BASED ON FUNCTION
• phospholipids
• sphingoglycolipids,
• cholesterol
Membrane component
Classification of Lipids
BASED ON FUNCTION
• bile acids
Emulsification
Classification of Lipids
BASED ON FUNCTION
• steroid hormones,
• eicosanoids
Messenger
Classification of Lipids
BASED ON FUNCTION
• biological waxes
Protective coating
hydrolysisoccurs & lipids are converted into 2 or more smaller molecules
• Triacylglycerols
• Phospholipids
• Sphingoglycolipids
• Biological waxes
Saponifiable
doesnotreact with water
• Cholesterol
• Steroid hormones
• Bile acids
• Eicosanoids
Nonsaponifiable
• Naturally occurring monocarboxylic acid • Usually contain
1. Evennumberofcarbons
2. unbranched carbon chain
3. Double bonds in a cis configuration (if present)
Fatty Acid
(t or f)
• Fatty acids may be classified based on the presence or absence of carbon-carbon double bonds
true
• all C-C bonds are single bonds
Saturated fatty acids
• one double bond
Monounsaturated Fatty Acids
• >1 double bond
Polyunsaturated Fatty Acids
• 2 numbers separated by a colon is used to denote length & number of C-C double bonds
• Carboxyl atom is C1
• Enclosed in parenthesis: Capital delta (Δ) with superscript indicating location of C-C double bonds
Delta Nomenclature
• C1 is the carbon atom on the methyl (noncarboxyl) end (ω)
• Family is determined by the location of the C-C double bond closest
to the omega end
Omega Nomenclature
• Most abundant type of lipid in the human body
• Lipid formed by esterification of 3 fatty acids to 1 glycerol molecule → triester + 3 H2O
• Location: within fat cells (adipocytes) found beneath the skin, in the abdominal cavity, in the mammary glands, and around various organs
• Simple – identical FAs
• Mixed – >1 type of FA
Triacylglycerols
• TAG mixture that is solid or semisolid at room temp
• Saturated fatty acids predominate
• Odorless, colorless, tasteless when pure
• Animal source
FATS
• TAG mixture that is liquid at room temp
• MUFAs and PUFAs predominate
• Odorless, colorless, tasteless when pure
• Plant source
• Fish source
OILS
(t or f)
• Both the type of dietary fat and amount of dietary fat are important
• Recommendations:
• Limit to 30% of total calories
§ Less than 10% saturated fat
§ Up to 15% monounsaturated fat
§ Up to 10% polyunsaturated fat
• Intake of omega-3 fatty acids – from deep/coldwater fish oils (albacore tuna, salmon, mackerel)
true
(t or f)
Fatty acid needed by the body that must be obtained from the diet as the body cannot synthesize them
true
• Needed for proper membrane structure
• Starting material for production of longer-chain fatty acids
Linoleic & Linolenic acid
eicosanoids
Arachidonic Acid
for normal brain & retinal development
EPA & DHA
Lipid that contains
§ 1 or more fatty acids
§ Phosphate group
§ Platform molecule – can be glycerol or sphingosine
§ Alcohol attached to phosphate
• Most abundant type of membrane lipid
Phospholipids
• Phospholipid that has glycerol as its platform molecule
• Lipid that contains
§ 2 fatty acids
§ Phosphate esterified to Glycerol
§ Alcohol esterified to PO4 group
• All attachments between its groups are ester linkages
• Head + 2 tails structure
• Can undergo hydrolysis and
saponification in a manner similar to TAGs
Glycerophospholipids
• Phospholipid that has sphingosine as its platform
• Lipid that contains
§ Fatty acid
§ Carbohydrate group – mono or disaccharide
§ Platform molecule –sphingosine
• Head + 2 tails structure
• Also undergo hydrolysis and saponification
Sphingophospholipids
• monosaccharide (Glucose or Galactose)
• Myelin sheath
Cerebrosides
• more complex branched chain of up to 7 monosaccharide residues
• grey matter & myelin sheath
Gangliosides
• C27 steroid molecule
• Most abundant steroid in the
body – precursor of other steroids
• Structure
§ C3: –OH
§ C10, C13: –CH3
§ C5-C6: =
§ C17 – 8C side chain
• Cell membranes
• Brain & nerve tissue
• Virtually all fluids
• Mostly synthesized by the liver &
intestines
Cholesterol
a lipid whose structure is based on a fused-ring system that involves three 6-membered rings & one 5-membered ring called the steroid nucleus
steroid
is a compact molecule with limited water solubility
Cholesterol
Cholesterol
• Distributed by protein carriers called
lipoproteins
• Oxygenated C20 fatty acid derivative that functions as a messenger lipid
• Precursor: Arachidonic Acid
• Produced by almost all cells except RBCs
• Exert their effects in the tissues
where they are synthesized
• Prostaglandins
• Thromboxanes
• Leukotrienes
Eicosanoids
Functions
• Mediation of inflammation
• Production of pain and fever • Regulation of blood pressure • Blood clotting
• Control of reproductive
functions, e.g. induction of labor • Regulation of sleep-wake cycle
Eicosanoids
• C20 structure containing a cyclopentane ring + oxygen- containing functional groups
• C8 and C12 become connected
to form a ring
• Inhibit secretion of gastric acid
• Increase protective mucus layer of
the stomach
• Contract or relax smooth muscle
• Raise body temperature
• Intensify pain
• Enhance inflammatory response
• Antithrombotic effect
Eicosanoids
• C20 structure containing a cyclic
ether ring + oxygen-containing
functional groups
• C8 and C12 become connected to form a ring
• Promote formation of blood clots – released by platelets to promote platelet aggregation
Eicosanoids
• C20 structure containing
3 conjugated double bonds and hydroxy groups
• Mediate inflammation and hypersensitivity
LEUKOTRIENES
• Monoester of long-chain fatty acid + long-chain alcohol • Fatty acids
• saturated
• 14-36 carbon atoms • Alcohols
• saturated or unsaturated
• 16-30 carbon atoms
• Water-insoluble, water-repellent
Functions
• Humans & animals –protect hair & skin to keep it pliable & lubricated
• Birds – keep feathers water-repellent & minimize loss of body heat
• Plants – prevent excessive evaporation and protect against parasitism • Pharmaceuticals, Cosmetics, Polishing
Biological Waxes
