FOB 4 lipids

• ampiphatic


  a molecule that has both polar and non-polar components
• lipids


  most energy-dense (more reduced) of all molecules in the body and diet, hydrophobic so need carrier proteins. types: triacylglycerols, glycerolipids, sphingolipids, sterols
• storage lipids

  fatty acids + triacylgylcerolds.
• fatty acids


  long hydrocarbon chain (4-36 in length, biologically active at 18 carbons or longer added in pairs) with a carboxyl group (de-protonated at biological pH). the cellular oxidation of fatty acids to Co2 and H2O is highly exergonic. saturated (no double bonds) unsaturated (containing 1 or more double bonds mono and poly unsaturated). unsaturated naturally occurring in cis formation, giving a kink, lowers MP and BP
• naming saturated fatty acids

  Saturated fatty acid (how many carbons present counting from carboxyl group):(number of double bonds 0)
• naming unsaturated fatty acid

  unsaturated fatty acid (length of chain from carboxyl group):(number of double bonds 1+) (delta (number that the double bond starts on)) then mono or polyunsaturated
• fatty acid structure rules

  even number of carbons. first double bond delta 9. additional delta 12 and delta 15. double bond are cis. double bonds are almost never conjugated (alternating single double), but separated by methylene group.
• omega (w) fatty acids


  count from last carbon in chain (methyl carbon) to describe omega 3 or omega 6 (double bonds on 3 and 6 carbon from omega ends). lack of omega 3 can cause heart problems, both are needed for body functioning and must be sourced from diet. omega 3 - alpha-linolenic acid ALA and omega 6 linoleic acid. acts a a precursor for synthesis of other unsaturated fatty acids.
• lipoproteins


  triacylglycerol and cholesterol need lipoproteins for transport. LDL - low-density lipoproteins, the primary carriers to peripheral tissue. HDL - take lipids and cholesterol from peripheral tissue to liver. high LDL starts depositing cholesterol in arterial walls causing atherosclerosis which hardens arterial walls, forms plaques, causes inflammation and then reduces flexibility causing ischemia (block of blood flow which kills off tissue) heart attack or even a stroke
• trans fatty acids


  trans double bonds can occur naturally but are more commonly synthesised during the hydrogenation of unsaturated fats. hydrogenation converts double bonds to single bonds but also changes cis to trans. trans fats lead to high LDL and low HDL because of how they metabolism. they can cause cardiovascular disease
• increasing melting point of lipids

  increase chain length so there are more hydrophobic interactions. increase saturation (less double bonds, less kinking) everything lies close together and is harder to separate
• triacylglycerol

  triglycerides/triacylglycerides. simplests lipids constructed from fatty acids. non-polar, mostly insoluble in water, more insoluble than a fatty acid as the hydroxyl head is lost. efficient store of energy. made of a glycerol back bone with fatty acids are attached to. 3 hydroxyl groups come off the glycerol and fatty acids form an ester bond. 2 are usually saturated, one is unusually unsatured in the middle. formed in a catalysed reversible condensation reaction producing 3 H2O. the catalyst activates the hydroxyl groups by covalently linkin to coenzyme acetyl-CoA.
• polar lipids

  glycerophospholipids - glycerol containing lipids and sphingolipids - sphingosine containing lipids or into two other families phospholipids (phosphate containing lipids. connects polar group to backbone) glycolipids (glucose or galactose containing lipids carbohydrate attached to glycerol or sphingosine backbone)
• glycerolphospholipid


  glycerol backbone with two fatty acids (one saturated c16-c18 one unsaturated c18-c20) and one phosphate ion with an alcohol attached. the final group becomes the hed-group substituent and bends around to sit above the molecule and form a polar head and non-polar tails. one unsaturated allows the membrane to space out. the alcohol group can differ and they are named based on the alcohol group
• sphingolipids

  sphingosine has its own long hydrocarbon chain that bends around and thus only needs one fatty acid and a phosphate with choline (phospholipid) to a mono or oligosaccharide (glycolipids). the link from the fatty acid to sphingosine is an amide link. the polar group is linked either via phosphate or a saccharide that gives polar properties
• sterols

  have a steroid nucleus consisting of four fused rings (3 6 carbon membered rings and 1 5 carbon membered ring) which gives the molecule a solid, planar and rigid backbone
• cholesterol


  major sterol found in animal tissue plays an important role as a component of cell membranes. long hydrophobic side chain and polar hydroxyl group. the ring structure increases membrane packing and thus decreases fluidity. an important precursor for steroid hormones (testosterone and cortisol), hydrophobic and long-lived but slow-acting (must be carried by a protein and are slow to be broken down)
• vitamins


  an organic compound that is required by an organism in limited amounts for the growth and health of the body. commonly they are not synthesised in sufficient quantities by the body and therefore must be obtained in the diet
• lipid-soluble vitamins

  A, D, E and K. D derived from UV absorption in the skin, plays a major role in calcium metabolism
• biological membranes

  fluid mosaic model. separate and protect intracellular components from the extracellular environment, and allow some substances to enter and exit but not all. sterols increase rigidity. self-sealing allows for endocytosis and exocytosis. selective permeability
• how are membranes formed

  amphipathic membranes (hydrophilic would dissolve away and hydrophobic would condense down in an aqueous environment). fatty acids form micelles where hydrophilic heads sit on the outside and the hydrophobic tails pack in and give no intracellular space, whereas polar lipids form a bilayer. enough lipids can form a liposome with a hollow core for intracellular material. fluid mosaic (everything continuously moves through the membrane)
• transport across a membrane

  selective permeability achieved through channels. simple diffusion (non-polar compound, down concentration gradient) facilitated diffusion (with electrochemical gradient) ion channels, ionophore mediated transport. active transport (against electrochemical gradient) primary and secondary.
• with electrochemical gradient, integral membrane proteins (have a hollow core for compounds to move through that alpha helixes alternate threading back and forth to create the core)

  facilitated diffusion
• primary active transport

  against the electrochemical gradient, energy is required.
• secondary active transport

  against gradient, piggybacking a substance against gradient with a substance that is going down its gradient. symport (both molecules move in same direction) and antiport (antiport, drives one out and the other in)
• primary + secondary transport

  primary and secondary active transport work together. a molecule is flushed out of the cell to a high concentration outside the cell so it is drawn in through secondary transport with another desired molecule