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Ebook Medical biochemistry at a glance (3rd edition): Part 2

(BQ) Part 2 book "Master techniques in surgery hernia" presentation of content: Lipids and lipid metabolism, metabolism of amino acids and porphyrins, vitamins, molecular biology, diagnostic clinical biochemistry. | 35  Structure of lipids CH2OH H H 15 C CHOH 13 C H CH2OH C16 H H H H H H 11 H H H H H C 9C 7C 5C 3C H H H H H H H H H O 1 C 18 OH H 14 C 12 C 10 C 8C 6C 4C H H H H H 12 14 15 13 10 11 4 6 8 7 9 5 17 2 1 C 3 18 OH 16 O 2C H 17 16 15 13 14 12 30° 11 2 4 6 8 10 H 9 7 5 3 1 C OH O Figure 35.1  Figure 35.2  Palmitic acid (hexadecanoic acid). A C16 Figure 35.3  Stearic acid Figure 35.4  cis-Oleic acid. A C18:1 Glycerol. A carbohydrate that forms the “backbone” of triacylglycerols (TAGs). saturated fatty acid, i.e. it has 16 carbon atoms, all of which (apart from the C1 carboxylic acid group) are fully saturated with hydrogen. (octadecanoic acid). A C18 saturated fatty acid, i.e. it has 18 carbon atoms, all of which (apart from the C1 carboxylic acid group) are fully saturated with hydrogen. This simplified representation of the structure does not show the hydrogen atoms. mono-unsaturated fatty acid, i.e. it has one double bond at C9, and so the carbon atoms C9 and C10 are not saturated with their full capacity of two hydrogen atoms each. NB The double bond creates a 30° angle. (cis- and trans- are defined in Fig. 35.14.) 17 16 O 3 C 6 4 O- 2 O 11 1 8 13 12 5 14 7 9 15 14 13 10 10 8 5 9 1 7 4 6 ω4 C 3 2 OH 18 17 20 17 18 C 21 9 3 22 8 10 11 1 5 4 C 2 OH O OH O Figure 35.7  Arachidonic acid. A C20:4 poly-unsaturated fatty acid, i.e. it has 20 carbon atoms and four cis-unsaturated bonds at C5, C8, C11 and C14. NB Arachidonic acid is sometimes mispronounced “arach-nid-onic”. Note that it is derived from peanuts (ground nuts; Greek arakos) and not from spiders (arachnids)! Figure 35.9  Docosahexaenoic acid (DHA). A C22:6 poly-unsaturated fatty acid, i.e. it has 22 carbon atoms and six cis-unsaturated bonds at C4, C7, C10, C13, C16 and C20. DHA is an essential fatty acid found in fish oil, and is a ω3 fatty .