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53 terms
lipids
lipids
1. organic compound found in living organisms that is insoluble (or sparingly soluble) in H₂O but soluble in non-polar organic solvents
2. fats
3. major way of storing chemical energy
4. fats surround & insulate organs
5. don't have common structural features
6. classification = basis of solubility, not funct. group
2. fats
3. major way of storing chemical energy
4. fats surround & insulate organs
5. don't have common structural features
6. classification = basis of solubility, not funct. group
5 categories of lipids
1. energy-storage lipids: triaclglycerols
2. membrane lipids: phospholipids, sphingoglycolipids, & cholesterol
3. emulsification lipids: bile acids
4. chemical messenger lipids: steroid hormones & eicosanoids
5. protective-coating lipids: biological waxes
2. membrane lipids: phospholipids, sphingoglycolipids, & cholesterol
3. emulsification lipids: bile acids
4. chemical messenger lipids: steroid hormones & eicosanoids
5. protective-coating lipids: biological waxes
structural formulas of lipids
1. structural diversity
2. esters, amides, alcohols (acyclic & cyclic) & polycyclic
2. esters, amides, alcohols (acyclic & cyclic) & polycyclic
fatty acids
1. naturally occurring monocarboxylic acid
a. carboxylic acids w/linear carbon chain
b. contain even number of carbon atoms
long chain = C₁₂-C₂₆
medium chain = C₈-C₁₀
short chain = C₄-C₆
a. carboxylic acids w/linear carbon chain
b. contain even number of carbon atoms
long chain = C₁₂-C₂₆
medium chain = C₈-C₁₀
short chain = C₄-C₆
fatty acids: 2 types
1. saturated: all C-C bonds, SB
2. unsaturated
a. monounsaturated (MUFA): 1 C=C bond
b. polyunsaturated (PUFA): 2 or more C=C bonds, up to 6
2. unsaturated
a. monounsaturated (MUFA): 1 C=C bond
b. polyunsaturated (PUFA): 2 or more C=C bonds, up to 6
saturated fatty acids (SFA)
1. numbering starts from end of -COOH
2. structural notation: indicated # of carbon atoms
ex. lauric acid has 12 carbons & no DB →12:0
2. structural notation: indicated # of carbon atoms
ex. lauric acid has 12 carbons & no DB →12:0
polyunsaturated fatty acid (PUFA)
1. usually referred by common name
2. Two numbers separated by colon, 1st designates the # of carbon, 2nd is the # of DB
Ex. 18:2 = 18 carbons, with 2 DBs
3. location of DBs use Δ. delta notation always has carboxyl carbon as C₁
ex. 18:3(Δ⁹'¹²'¹⁵) = 18 carbons, 3 DBs, located btw 9-10, 12-13 & 15-16 carbons
4. MUFA;s are usually Δ⁹ acids
5. polyunsaturated are usually at the Δ¹² & Δ¹⁵
2. Two numbers separated by colon, 1st designates the # of carbon, 2nd is the # of DB
Ex. 18:2 = 18 carbons, with 2 DBs
3. location of DBs use Δ. delta notation always has carboxyl carbon as C₁
ex. 18:3(Δ⁹'¹²'¹⁵) = 18 carbons, 3 DBs, located btw 9-10, 12-13 & 15-16 carbons
4. MUFA;s are usually Δ⁹ acids
5. polyunsaturated are usually at the Δ¹² & Δ¹⁵
biologically important UFAs: define & 2 types
1. several different families, characterized by location of DB relative to methyl end of fatty acid
2. Omega-3 fatty acid: endmost DB is 3 carbons from methyl group
3. Omega-6 fatty acid: endmost DB is 6 carbons from methyl group
2. Omega-3 fatty acid: endmost DB is 3 carbons from methyl group
3. Omega-6 fatty acid: endmost DB is 6 carbons from methyl group
physical properties of fatty acids
1. water solubility: short chains have some solubility (b/c of carboxylic acid polar group), long chains are insoluble
2. MP depends on # of C atoms & degree of saturation
a. DB (usually "cis") put a bend in chain, & bend keep unsaturated FA from packing as tightly as saturated & have fewer intermolecular attractions = ↓ MP
2. MP depends on # of C atoms & degree of saturation
a. DB (usually "cis") put a bend in chain, & bend keep unsaturated FA from packing as tightly as saturated & have fewer intermolecular attractions = ↓ MP
energy storage materials: general
1. cells store energy material for when energy demand is high
2. most storage material is carbohydrate glycogen
3. lipid storage=triacylglycerols
2. most storage material is carbohydrate glycogen
3. lipid storage=triacylglycerols
energy storage materials: triacylglycerols
a lipid formed by esterification of 3 fatty acids + glycerol
1. most abundant, concentrated in adipocytes (adipose tissue) which are located in various parts of body
2. more efficient than glycogen: large quantities packed in small volumes
3. three ester functional groups
4. alcohol is always glycerin
5. non-polar
1. most abundant, concentrated in adipocytes (adipose tissue) which are located in various parts of body
2. more efficient than glycogen: large quantities packed in small volumes
3. three ester functional groups
4. alcohol is always glycerin
5. non-polar
2 types of triacylglycerols
1. simple = 3 identical fatty acids (these are rare)
2. mixed = more than 1 kind of fatty acid. includes most biochemically important triacylglycerols. different mixed depend on climate & feed source
2. mixed = more than 1 kind of fatty acid. includes most biochemically important triacylglycerols. different mixed depend on climate & feed source
fats
1. naturally occurring mixtures of triacylglycerols
2. difference btw fats & oils is physical state
3. predominantly saturated
4. solids or semi-solids at room temp.
5. obtained from animals
6. pure fats & oils are colorless, odorless & tasteless
2. difference btw fats & oils is physical state
3. predominantly saturated
4. solids or semi-solids at room temp.
5. obtained from animals
6. pure fats & oils are colorless, odorless & tasteless
oils
1. naturally occurring mixtures of triacylglycerols
2. difference btw fats & oils is physical state
3. predominantly unsaturated
4. liquids at room temp.
5. obtained from plants & fish oils
6. pure fats & oils are colorless, odorless & tasteless
2. difference btw fats & oils is physical state
3. predominantly unsaturated
4. liquids at room temp.
5. obtained from plants & fish oils
6. pure fats & oils are colorless, odorless & tasteless
"good fats" vs "bad fats"
1. saturated fats are bad fats
2. monounsaturated fats are good fats
3. trans-monoumsaturated fats are bad fats
4. polyunsaturated fats can be both good & bad
5. omega 6 & omega 3 good fats
2. monounsaturated fats are good fats
3. trans-monoumsaturated fats are bad fats
4. polyunsaturated fats can be both good & bad
5. omega 6 & omega 3 good fats
essential fatty acid
1. a fatty acid needed in human body that must be obtained from dietary sources, b/c not enough can be synthesized in body.
essential fatty acid: 2 types
1. linoleic acid (18:2) omega 6
2. linolenic acid (18:3) omega 3
both needed for
a. proper membrane structure
b. starting point for longer chain omega 3 & 6 fatty acids
2. linolenic acid (18:3) omega 3
both needed for
a. proper membrane structure
b. starting point for longer chain omega 3 & 6 fatty acids
chemical reactions: types
due to 2 functional groups: esters & alkenes
1. hydrolysis
2. saponification
3. hydrogenation
4. oxidation
1. hydrolysis
2. saponification
3. hydrogenation
4. oxidation
chemical reactions: hydrolysis
1. reverse of esterification
2. in lab = complete hydrolysis
3. in body = partial hydrolysis
a. occurs during digestion
b. break 1-2 ester bonds→mono- or diacylglycerol & fatty acids
c. carried out by enzymes from pancreas
2. in lab = complete hydrolysis
3. in body = partial hydrolysis
a. occurs during digestion
b. break 1-2 ester bonds→mono- or diacylglycerol & fatty acids
c. carried out by enzymes from pancreas
chemical reactions: saponification
1. hydrolysis in basic solution→salt of fatty acid + glycerol
2. it is the process that turns animal fat into soap
2. it is the process that turns animal fat into soap
chemical reactions: hydrogenation
1. addition of hydrogen across a DB
2. changes from unsaturated into saturated fatty acids
3. many foods produced by partial hydrogenation. ex. peanut butter
2. changes from unsaturated into saturated fatty acids
3. many foods produced by partial hydrogenation. ex. peanut butter
chemical reactions: oxidation
1. DB in triacylglycerols subject to oxidation from oxygen in air → breaking C=C bond
2. oxidation of alkenes may result in 2 short chains that can be aldehydes or carboxylic acids.
- when produced these can have bad odors (fats/oils said to be rancid.
- to avoid, antioxidants are added
2. oxidation of alkenes may result in 2 short chains that can be aldehydes or carboxylic acids.
- when produced these can have bad odors (fats/oils said to be rancid.
- to avoid, antioxidants are added
membrane lipids: general & 3 types
- cells surrounded by membrane to confine contents
- up to 80% of mass of cell membrane can be lipids
3 types
1. phospholipids
2. sphingolycolipids
3. cholesterol
- up to 80% of mass of cell membrane can be lipids
3 types
1. phospholipids
2. sphingolycolipids
3. cholesterol
membrane lipids: phospholipids definition
a lipids that contains 1 or more fatty acids, a phosphate group, a platform molecule (glycerol or sphingosine) to which the fatty acids & phosphate group are attached, and an alcohol attached to phosphate group
membrane lipids: glycerophospholipids
1. a lipid with glycerol platform, 2 fatty acids & a phosphate (with an attached alcohol)
2. 4 ester linkages
3. undergo hydrolysis & saponification
4. alcohol attached to phosphate usually 1 of 3 amino alcohols: choline, ethanolamine, serine
5. structurally similar to triacylglycerols but they are components of membrance vs. energy storage
6. structural characteristic is that it contains a polar and non-polar end
2. 4 ester linkages
3. undergo hydrolysis & saponification
4. alcohol attached to phosphate usually 1 of 3 amino alcohols: choline, ethanolamine, serine
5. structurally similar to triacylglycerols but they are components of membrance vs. energy storage
6. structural characteristic is that it contains a polar and non-polar end
membrane lipids: sphingophospholipids
1. lipid that contains 1 fatty acid, 1 phosphate group (with an attached alcohol) attached to a sphingosine.
2. fatty acid attached to the -NH (amide linkage) & phosphate attached to the terminal -OH (ester linkage)
3. head and two tail structure
2. fatty acid attached to the -NH (amide linkage) & phosphate attached to the terminal -OH (ester linkage)
3. head and two tail structure
membrane lipids: sphingoglycolipids
1. lipid that contains a fatty acid (amide linkage) & a carbohydrate (Mono or poly - glycosidic linkage) attached to a sphingosine molecule
2. simple ones called cerebrosides - contain single mono (either glucose or galactose). primarily in brain
2. simple ones called cerebrosides - contain single mono (either glucose or galactose). primarily in brain
membrane lipids: cholesterol
1. much different that other membrane lipids
2. C₂₇ steroid molecule is component of cell membrane & precursor for other steroid lipids
3. most abundant steroid in human body
4. important in human cell membranes, nerve & brain tissue
5. does not have head & two tails
6. lack of large polar ends = limited water solubility
2. C₂₇ steroid molecule is component of cell membrane & precursor for other steroid lipids
3. most abundant steroid in human body
4. important in human cell membranes, nerve & brain tissue
5. does not have head & two tails
6. lack of large polar ends = limited water solubility
steroid
lipid whose structure is based on a fused ring system that involves three 6 carbons rings & one 5 carbon ring
cholesterol in food
1. liver synthesizes cholesterol, so not necessary to consume
2. synthesis ↓ if cholesterol ingested, but not enough
3. leads to heart disease
4. animal products = lots of cholesterol/plant products= little cholesterol
2. synthesis ↓ if cholesterol ingested, but not enough
3. leads to heart disease
4. animal products = lots of cholesterol/plant products= little cholesterol
cells: general
1. surrounded by plasma membrane. 80% are lipids
2. membranes are lipids bilayers (polar heads, non-polar tails)
3. membrane is liquid like structure due to unsaturation in lipid tails
2. membranes are lipids bilayers (polar heads, non-polar tails)
3. membrane is liquid like structure due to unsaturation in lipid tails
cells: cholesterol
1. cholesterol component of plasma membrane
2. helps regulate membrane fluidity
3. fits btw fatty acid chains of lipid bilayer=rigidity
2. helps regulate membrane fluidity
3. fits btw fatty acid chains of lipid bilayer=rigidity
cells: protein
1. plasma membrane contains proteins
2. responsible for moving substances across membrane
3. receptors for hormones & neurotransmitters
4. proteins and some lipids are further reacted w/carbohydrate molecules. serve as markers
2. responsible for moving substances across membrane
3. receptors for hormones & neurotransmitters
4. proteins and some lipids are further reacted w/carbohydrate molecules. serve as markers
transport across cell membrane: Passive
1. substance moves across membrane by diffusion, from high to low concentration, without energy
2. only a few can. ex. O₂,N₂,H₂O, urea & ethanol
2. only a few can. ex. O₂,N₂,H₂O, urea & ethanol
transport across cell membrane: facilitated
1. substance moves across membrane by with the aid of a membrane protein, from high to low concentration, without energy
2. specific proteins are called carriers or transporters
3. glucose, chloride ion & bicarbonate ion use this method
2. specific proteins are called carriers or transporters
3. glucose, chloride ion & bicarbonate ion use this method
transport across cell membrane: active transport
1. substance moves across membrane by with the aid of a membrane protein, from against (low to high) concentration, expending energy
2. proteins are called pumps b/c they need energy
3. energy supplied by molecules such as ATP
4. sodium, potassium & hydronium ions use this method
2. proteins are called pumps b/c they need energy
3. energy supplied by molecules such as ATP
4. sodium, potassium & hydronium ions use this method
emulsifier
1. substance that can disperse & stabilize water-insoluble substances as colloidal particles in an aqueous solution. (similar to soap during washing)
bile acid
1. a cholesterol derivative (tri-or dihydroxy cholesterol derivatives) that functions as a lipid emulsifying agents in the aqueous environment of digestion.
2. the C₁₇ side chain of cholesterol has been oxidized to carboxylic acid. & then bonded to an amino acid thru amide linkage
3. makes dietary lipids soluble
4. approx. 1/3 of cholesterol produced by liver is converted to bile (by oxidation)
2. the C₁₇ side chain of cholesterol has been oxidized to carboxylic acid. & then bonded to an amino acid thru amide linkage
3. makes dietary lipids soluble
4. approx. 1/3 of cholesterol produced by liver is converted to bile (by oxidation)
bile
1. fluid containing emulsifying agents (bile acids) secreted by the liver, stored in gallbladder, & released into small intestine during digestion
2. gallstones=crystallized cholesterol
2. gallstones=crystallized cholesterol
hormone
1. biochemical substance, produced by a ductless gland, that has a messenger function
2. hormones communicate btw various tissues
3. some are lipids
4. lipids that are chemical messengers=steroid hormones & eicosanoid
2. hormones communicate btw various tissues
3. some are lipids
4. lipids that are chemical messengers=steroid hormones & eicosanoid
Lipid chemical messenger: steroid - define & 2 classes
1. hormone that is a cholesterol derivative
2. two classes
a. sex hormones: reproduction & sex characteristics
1. estrogen: female sex hormone
2. androgens: male sex hormone
3. progestins: pregnancy hormone
b. adrenocorticoid hormones: produced by adrenal glands, 28 different hormones
a. mineralocorticoids=controls Na & K balances in cell
b. glucocorticoids=controls glucose metabolism & counteract inflammation
2. two classes
a. sex hormones: reproduction & sex characteristics
1. estrogen: female sex hormone
2. androgens: male sex hormone
3. progestins: pregnancy hormone
b. adrenocorticoid hormones: produced by adrenal glands, 28 different hormones
a. mineralocorticoids=controls Na & K balances in cell
b. glucocorticoids=controls glucose metabolism & counteract inflammation
Lipid chemical messenger: steroid/adrenocorticoid/mineralcorticoid
control the balance of Na and K ions in cells
Lipid chemical messenger: steroid/adrenocorticoid/glucocorticoids
controls glucose metabolism & counteracts inflammation
Lipid chemical messenger: eicosanoid
1. oxygenated C₂₀ fatty acid derivative that functions as a chemical messenger
2. precursor for eicosanoid is arachidonic acid (20:4)
3. profound physiological effects at low concentrations
4. hormone-like molecules
5. effects at tissues where synthesized
6. very short life
2. precursor for eicosanoid is arachidonic acid (20:4)
3. profound physiological effects at low concentrations
4. hormone-like molecules
5. effects at tissues where synthesized
6. very short life
Lipid chemical messenger: eicosanoid physiological effects (6)
1. inflammatory response
2. production of pain & fever
3. regulation of blood pressure
4. induction of blood clotting
5. control of reproductive functions: labor
6. regulation of sleep/wake cycle
2. production of pain & fever
3. regulation of blood pressure
4. induction of blood clotting
5. control of reproductive functions: labor
6. regulation of sleep/wake cycle
Lipid chemical messenger: eicosanoid-3 types
1. prostaglandins
2. thromboxanes
3. leukotrienes
2. thromboxanes
3. leukotrienes
Lipid chemical messenger: eicosanoid-prostaglandins
1. messenger lipid that is a C₂₀ fatty acid derivative that contains a cyclopentane ring & oxygen-containing functional groups
2. >20 discovered
involved with
a. raising body temp
b. inhibiting secretion of gastric juices
c. ↑ secretion of protective mucus layer into stomach
d. relaxing & contracting smooth muscle
e. directing water & electrolyte balance
f. intensifying pain
g. enhance inflammation responses
2. >20 discovered
involved with
a. raising body temp
b. inhibiting secretion of gastric juices
c. ↑ secretion of protective mucus layer into stomach
d. relaxing & contracting smooth muscle
e. directing water & electrolyte balance
f. intensifying pain
g. enhance inflammation responses
Lipid chemical messenger: eicosanoid-thromboxanes
1. messenger lipid that is a C₂₀ fatty acid derivative that contains a cyclic ether ring & oxygen-containing functional groups
2. promote formation of blood clots
3. produced by blood platelets & promote platelet aggregation
2. promote formation of blood clots
3. produced by blood platelets & promote platelet aggregation
Lipid chemical messenger: eicosanoid-leukotrienes
1. messenger lipid that is a C₂₀ fatty acid derivative that contains a three conjugated DBs & hydroxy groups
2. promote inflammatory & hypersensitivity (allergy) responses
2. promote inflammatory & hypersensitivity (allergy) responses
biological wax - define
1. lipid that is a monoester of a long chain fatty acid + a long chain alcohol
biological wax - 2 types
1. fatty acids:
a. generally saturated fatty acids
b. 14-36 carbon atoms
2. alcohols:
a. may be saturated or unsaturated
b. 16-30 carbon atoms
a. generally saturated fatty acids
b. 14-36 carbon atoms
2. alcohols:
a. may be saturated or unsaturated
b. 16-30 carbon atoms
biological wax - properties
1. water insoluble & water repellent b/c of long non-polar hydrocarbons
2. humans & animals secrete biological waxes from skin glands
2. humans & animals secrete biological waxes from skin glands
biological wax - functions
1. protect hair & skin: keeps pliable & lubricated
2. impart water repellency to animal fur
3. keeps bird feather water repellent & reduces loss of body heat
4. plants have coat on leaves to prevent water loss & to protect from parasites
2. impart water repellency to animal fur
3. keeps bird feather water repellent & reduces loss of body heat
4. plants have coat on leaves to prevent water loss & to protect from parasites