FT LEC: Lipids Flashcards
an organic compound found in living organisms that are insoluble (or sparingly soluble) in water but soluble in nonpolar organic solvents
Lipids
Structurally diverse; has no repeating unit structure like the other biomolecules
Lipids
can be extracted when biochemical material (human, animal, or plant material) is homogenized and mixed with nonpolar organic solvent
Lipids
Classification of lipids
- Based on hydrolysis characteristics
- Based on biological function
Hydrolyzable lipids
- Triacylglycerols
- Membrane lipids
- Biological waxes
can be broken down to simpler molecules through hydrolysis
Hydrolyzable lipids
can no longer be broken down to simpler molecules
Non-hydrolyzable lipids
Non-hydrolyzable lipids
- Steroids
- Eicosanoids
- Emulsification Lipids
Based on biological function
- Energy storage lipids
- Membrane lipids
- Emulsification lipids
- Messenger lipids
- Protective-coating lipids
is a naturally occurring monocarboxylic acid with long, unbranched hydrocarbon chains that nearly always contain an even number of carbons
Fatty acids
Fatty Acid: Classification according to length
- Long fatty acid chains (12C to 26C)
- Medium fatty acid chains (8C to 10C)
- Short fatty acid chains (4C to 6C)
Fatty Acid: Classification based on presence of C=C bonds
- Saturated fatty acids
- Unsaturated fatty acids
only contain carbon-carbon single bonds
Saturated fatty acids
Unsaturated fatty acids can be further classified into two sub-types
- Monounsaturated fatty acids (MUFAs)
- Polyunsaturated fatty acids (PUFAs)
contain at least one carbon-carbon double bond
Unsaturated fatty acids
contain only one carbon-carbon double bond
Monounsaturated fatty acids (MUFAs)
contain at least two carbon-carbon bonds
Polyunsaturated fatty acids (PUFAs)
produce bends or kinks that prevents stronger interaction between the hydrocarbon chains
Carbon-carbon double bonds in the cis configuration
Unsaturated fatty acids have _____ melting and boiling points compared to saturated fatty acids
lower
is a lipid formed by esterification of three fatty acid molecules to a glycerol molecule
triacylglycerol (TAG)
is a tri-ester formed from the esterification of glycerol with three identical fatty acid molecules
Simple triacylglycerol
is composed of unidentical fatty acid molecules (more biochemically important)
Mixed triacylglycerol
take in the form of fats or oils in nature, which are the most abundant types of lipid as well
Triacylglycerols
are triacylglycerol mixtures that are solid or semi-solid at room temperature and is generally obtained in animals
Fats
are triacylglycerol mixtures that are liquid at room temperature
Oils
is a fatty acid needed in the human body that must be acquired from dietary sources because it cannot be synthesized by the human body in adequate amounts from other substances
Essential fatty acid
are considered bad fats
Saturated fats
are considered good fats
Unsaturated fats
are particularly important
Omega fatty acids
Two essential fatty acids
- Linoleic acid
- Linolenic acid
needed for proper cell membrane formation
Linoleic acid
Serves as starting material for other biochemically important fatty acids
Linoleic acid
Precursors to eicosapentanoic acid (EPA) and docosahexanoic acid (DHA)
Linolenic acid
are important constituents of cell membrane of nerve cells, and are active components in the retinas
EPA and DHA
Three common membrane lipids
- Phospholipids
- Sphingophospholipids
- Cholesterol
are phospholipids that contain two fatty acids and a phosphate group bonded to a glycerol molecules by ester bonds, and an alcohol bonded to the phosphate group
Glycerophospholipids
Also known as lecithins
Phosphatidylcholine
Also known as cephalins
Phosphatidylethanolamine and Phosphatidylserine
are phospholipids that contain sphingosine molecule with a fatty acid bonded to it with amide bonds, a phosphate group, and an alcohol bonded to the phosphate group
Sphingophospholipid
Sphingophospholipids with choline attached to the phosphate group are called ____________
sphingomyelins
Found in cell membranes and main structural components of myelin sheaths
sphingomyelins
are lipids that contain both fatty acids and a carbohydrate (usually a monosaccharide) bonded to sphingosine
Sphingoglycolipids
Types of Sphingoglycolipids
- Cerebroside
- Ganglioside
Possesses a monosaccharide unit usually glucose or galactose
Cerebroside
Simplest sphingoglycolipid
Cerebroside
Complex sphingoglycolipid
Ganglioside
Possesses branched carbohydrate component
Ganglioside
Occurs in the grey matter of the brain and in the myelin sheath
Ganglioside
is a type of steroid (a lipid whose structure is based on a fused ring system that involves three six-membered rings and one five-membered ring)
Cholesterol
A 27-carbon molecule that is a component of cell membranes and a precursor of other steroid-based lipids
Cholesterol
Found in animal fat and can be synthesized in the liver
Cholesterol
is a lipid-based structure that separates a cell’s aqueous interior from the aqueous environment surrounding the cell
cell membrane
a long, thick structure of phospholipids and glycolipids in which the nonpolar tails of the lipids are in the middle and the polar heads are on the outside surfaces of the structure
cell membrane
The components of cell membranes occur in different amount depending on the cell’s function
- Phospholipids
- Glycolipids
- Cholesterol
- Proteins
There are two types of proteins in cell membranes
- Integral proteins
- Peripheral proteins
penetrate both sides of the lipid bilayer
Integral proteins
only found on one side of the lipid bilayer
Peripheral proteins
concentration: high to low
cellular ee: none required
protein help: none required
Passive transport
concentration: high to low
cellular ee: none required
protein help: proteins serve as “gates”
Facilitated transport
concentration: low to high
cellular ee: energy input required
protein help: proteins serve as “pumps”
Active transport
Some lipids are hormones or at least perform a messenger function
- Steroid hormones
- Eicosanoids
are biochemical substances produced by ductless glands that have a messenger function and serve as communication between cells
Hormones
Hormones: are derived from cholesterol
Steroid hormones
Hormones: are derived from the fatty acid arachidonic acid
Eicosanoids
Two classes of steroid hormones
- Sex hormones
- Adrenocorticoid hormones
control reproduction and the development of secondary sexual characteristics
Sex hormones
are produced in the ovaries and promotes development of secondary female characteristics
Estrogens
are produced in the testes and promotes development of secondary male characteristics; also promotes muscle growth
Androgens
are pregnancy hormones that control ovulation and prepares the uterine lining for implantation
Progestins
are used as oral contraceptives or anabolic steroids
Artificial hormones
control and regulate various biochemical functions
Adrenocorticoids
control the Na+/K+ balance in the body
Mineralocorticotropic hormones
control and regulate glucose metabolism and counteracts inflammation process
Glucocorticotropic hormones
are used as anti-inflammatory drugs in allergic reactions (hypersensitivity)
Synthetic adrenocorticoids
are oxygenated 20-carbon fatty acid derivatives that function as a messenger lipid
Eicosanoids
Three principal types of eicosanoids
- prostaglandins
- thromboxanes
- leukotrienes
is a messenger lipid that as a C20 fatty acid derivative that contains a cyclopentane ring and oxygen-containing functional groups
prostaglandin
is a C20 fatty acid derivative that contains a cyclic ether ring and oxygen-containing functional groups
thromboxane
is a C20 fatty acid derivative that contains three conjugated double bonds and hydroxyl groups
Leukotriene