Fats, oils, fatty acids, steroids, and terpenes {lipid}| are complex hydrocarbons. Terpenes and steroids are simple lipids. Fatty-acid-based lipids are complex lipids. Lipids are for insulation and energy storage. Cell membranes and hormones have lipids. Most lipids are insoluble in water. Lipids can have polar ends and be soluble in water. Lipids contain 2.25 times more energy, by mass, than do carbohydrates or proteins, because they can oxidize more.
lipid disease
Lipids can make gall bladder contract {gall bladder disease}. Gallstones can block bile-salt flow. Cystic fibrosis is inherited low ability to digest fat.
Fatty acids can break down {fatty-acid oxidation} {beta-oxidation} in mitochondria.
functions
Fat tissue hydrolyzes and esterifies fat and oil if body needs energy. Muscle uses fatty acids when resting.
process
In fat cells, lipase binds to triglyceride to split glycerol from fatty acid. Blood serum albumin carries fatty acids to tissues. In tissues, ATP adds CoA to fatty-acid carboxyl end to make acetyl group. Process repeatedly removes acetyl group, with two carbons, from fatty-acid end. Unsaturated bonds become trans, not cis, isomers.
products
Fatty-acid oxidation makes ATP, NADH, acetyl-CoA, and water. Camels store fat in humps, not water.
factors
B vitamins and pantothenic acid affect fat breakdown and synthesis.
Enzymes {lipase} can catabolize triglycerides.
Molecules {emulsifier}, with polar and non-polar ends, can bind non-polar end to fat molecule and dissolve polar end in water {emulsification}|, to make micelles.
Acetyl-CoA added to another acetyl-CoA makes carboxylic acid, and then fatty-acid chain adds two-carbon acetyl-CoA {fatty-acid synthesis}. Cytoplasm has fatty-acid synthesis.
Air oxidizes fats {rancid}|.
Strong hydroxide can break triglyceride into glycerol and fatty-acid salts, both of which can dissolve in water {saponification}|.
If carbohydrate level is too low, cell makes acetyl-CoA. Acetone, acetoacetate, and beta-hydroxybutyrate {ketone body} accumulate.
Carboxylic acids {fatty acid}| can have long hydrocarbon chains. Fatty acids have even numbers of carbons, from 12 to 20. Liver regulates fatty acids in blood.
Sphingosine, ceramide, sphingomyelin, and cerebroside {cell-surface lipid} determine blood group, direct development, make organ structures, confer immunity, and signal cancer.
Blood has triglyceride globular micelles {chylomicron}. Non-polar ends are inside, and polar ends, which dissolve in water, are on surface. Lipids digest slowest. Intestine absorbs 95% of lipids.
Triglycerides {phosphoglyceride} can have fatty acids replaced by phosphates. Cell-membrane phosphatidic acid, lecithin or phosphatidyl choline, and cephalin or phosphatidyl ethanolamine are phosphoglycerides.
Ether group can replace triglyceride fatty acid {plasmalogen}.
CDP, serine, ethanolamine, or choline can replace phosphatidic-acid phosphate group to make other lipids {sphingolipid}. Palmitic acid, in CoA form, adds serine to replace CoA and then reduces to sphingosine. Acyl CoA can bind to sphingosine to make ceramide. CDP-choline can bind to ceramide to make sphingomyelin. UDP-sugar can bind to ceramide to make cerebroside. Sialic acid can bind to cerebroside to make ganglioside. Ganglioside is in synapses and nerve receptors.
Cell-surface lipids {sulfatide} can determine blood group, direct development, structure organs, confer immunity, and signal cancer.
Lipids {triglyceride}| {triacylglycerol} can combine three fatty acids and one glycerol. Glycerol can attach fatty acid at each alcohol. Triglycerides {fat, biochemistry} can have three saturated fatty acids. Triglycerides {oil, biochemistry} can have three unsaturated fatty acids.
synthesis
Dihydroxyacetone phosphate reduces to glycerol-3-phosphate, in glycolysis pathway. Acetyl-CoA binds to two glycerol-3-phosphate hydroxyls, to make phosphatidic acid. Replacing phosphatidic acid phosphate group with fatty acid makes triglyceride.
Fatty-acid esters {wax, lipid} can have long chain alcohols or sterols. Carnauba wax is hard and lustrous and is for floor, car, and furniture. Candelilla wax is brown and is for records, floor, and candles. Bayberry wax is for candles. Beeswax is for cosmetics, candles, polishes, crayons, and artificial flowers. Wool wax is purified lanolin for ointments, cosmetics, and soaps.
Petroleum wax is odorless, tasteless, and inactive. Paraffin is hard petroleum wax for paper coatings. Petroleum jelly is soft petroleum wax for medicine.
Four-carbon alkenes {butadiene} can have two double bonds. Butadiene can single bond a side chain to second carbon. Butadiene can attach a methyl group to make isoprene. Butadiene can attach tertiary carbon to make neoprene.
Butadiene {isoprene}| can attach methyl-group side chain. Polymers can be isoprene chains, with fifth carbon attached to second carbon. Rubber is natural isoprene polymer.
Butadiene {neoprene} can single bond a tertiary-carbon side chain on second carbon.
Organic molecules {terpene}| can use isoprene structure. Monoterpenes are geranium, lemon, mint, turpentine, camphor, and caraway. Linear polyterpenes are rubber and gutta-percha. Fat-soluble terpenes are vitamin A, vitamin E, vitamin K, and carotene. Polyprenols are coenzyme Q, bactoprenol or dolichol hydrogen carrier, and phytol in chlorophyll. Squalene makes cholesterol. Rubber and gutta-percha are terpenes.
Proteins {lipoprotein}| can carry lipids in blood. Serum albumin carries short-chain fatty acids in blood.
Lipoproteins {high-density lipoprotein}| (HDL) can carry phospholipids.
Lipoproteins {low-density lipoprotein}| (LDL) can carry cholesterol.
Lipoproteins {very low-density lipoprotein}| (VLDL) can carry triglycerides.
Hydrocarbon chains {mono-unsaturated hydrocarbon}| {monounsaturated hydrocarbon} can have one double bond and no triple bonds.
Hydrocarbon chains {polyunsaturated hydrocarbon}| can have more than one double bond.
Hydrocarbon chains {saturated hydrocarbon}| can have no double or triple bonds between carbons and hold maximum hydrogens.
Cholesterol is the fundamental structure in many hormones {steroid hormone}|.
biology
Steroids induce enzymes to increase glucose usage and start stress response. Sex steroids and glucocorticoid hormones have neuron receptors.
types
Ergosterol makes vitamin D.
Bile acids emulsify and absorb lipids in small intestine.
Male sex-hormone androgens include testosterone and androstenol. Female sex-hormone estrogens include estrone, estradiol, and progesterone.
Adrenocorticosteroids, such as corticosterone and aldosterone, control body water amount. Cortisone reduces inflammation.
Digitoxin affects heart rate.
Lipids {cholesterol}| can have quadruple aromatic carbon rings. Cholesterol is the fundamental structure in steroid hormones. Plants have no cholesterol, which is only in animals.
process
Acetate becomes acetyl-CoA and acetoacetyl-CoA. Added water makes 3-hydroxy-3-methyl-glutaryl CoA, which reduces to mevalonate when CoA leaves. ATP adds three phosphates to alcohol oxygens to reduce mevalonate to activated isoprene isopentyl pyrophosphate. Isoprenes cyclically add to make squalene. Squalene epoxide makes cholesterol. Adding functional groups to ring carbons makes other steroids from cholesterol.
Lipids {sterol}| can have quadruple aromatic carbon rings. Plant sterols {phytosterol} include campesterol, sitosterol, and stigmasterol. Animal sterols {zoosterols} include cholesterol.
Lipids {stanol}| can be saturated sterols. Stanols can add fatty acids to make stanol esters.
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Date Modified: 2022.0225