CHEM 1516 Biochem II Abby's Notes Part IV

CHEM 1516 Biochem II Abby's Notes Part IV - Biochem II...

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Biochem II Notes PART 4 I. LIPID METABOLISM A. General Info 1. Definition of LIPID = Insoluble in water, soluble in an organic solvent 2. Other courses on lipids topics including. .. a. absorption b. digestion c. transport d. storage diseases e. For more info, see Champe : Lippincott Review 3. Lipids are a large and varied class of macromolecules including. .. a. Stored Energy = Fats: Triacylglycerols (Triglycerides) are stored ATP b. Membrane Lipids = Phospholipids: glycerophospholipids (Lecithins) c. Membrane Surface (ID tags) = Glycolipids d. Steroids: Cholesterol, some hormones, bile acids e. Eicosanoids: Prostaglandins et al. f. Fat Soluble Vitamins: A, D, E, K 4. Fatty Acids = the simplest lipids a. Structure 1) C-C-C-C-C-C-C-C-C-C-C-C-C-C-C – COOH (hydrocarbon w/ carboxyl head group) 2) Hydrocarbon is usually 16 – 24 Carbons long 3) Saturation i. Saturated FAs have NO C – C double bonds (C=C). They are saturated w/ hydrogen! ii. Unsaturated FAs have at least one C=C (double bonds). They have a bent structure. 4) FAs are Amphipathic (meaning they have both polar and non-polar parts on the same molecule). The COOH head is hydrophilic, the long Carbon chain is hydrophobic. The salts of FAs (the COO-) are emulsifiers (soap, detergent) b. More Info 1) In the body, FAs are found free or esterified 2) FAs are used for energy or biosynthesis 3) Most FAs are supplied by the diet, but excess CHOs and Proteins are turned into FAs which are stored as Triglycerides (FAT) c. Major Common FAs 1) Denoted by # of carbons : # of double bonds (with the location of the double bond in parenthesis) 2) Palmitic C16:0 This is the prototype that we will follow through synthesis 3) Stearic C18:0 4) Palmitoleic C16:1 (delta 9) 5) Oleic C18:1 (9) 6) Linoleic C18:2 (9,12) an essential FA (EFA) 7) Linolenic C18:3 (9, 12, 15) also an EFA 8) Arachidonic C20:4 (5,8,11,14) the precursor of eicosanoids (PGs)
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5. Synthesis of FAs a. Fatty Acids are grown by the addition of 2 carbons at a time b. FA Synthesis 1) Glucose is the major source of Acetyl CoA: Glucose glycolysis → 2 Pyruvate → pyruvate dehydrogenase → 2 Acetyl CoA 2) Acetyl CoA is formed inside the mitochondria (via oxidative decarboxylation of pyruvate via PDH ). It must be carried out to the cytoplasm. CITRATE is the carrier molecule. 3) Acetyl unit (2Cs, a S, & a protein) + Malonyl unit (3 Cs, a S, & a protein) → condensation (loose a CO 2 ) → reduction dehydration (take away H 2 O) → reduction (NAD P H + H + → NAD P c. DeNovo Synthesis (from scratch, brand new) 1) Occurs in the cytoplasm of liver, kidney, adipose tissue, and lactating mammary gland. 2) Adds 2 Carbons (acetyl group) to saturated Fatty Acids 3) A 4 step sequence: Acetyl CoA and Malonyl CoA are the substrates i. Malonyl (C3) + Acetyl (C2) → condensation w/ loss of 1 carbon ii. → reduction using (NAD P H +H + → NAD P ) iii. → dehydration (loose water) iv. → reduction using (NAD
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This note was uploaded on 11/21/2011 for the course CHEM 1516 taught by Professor Bertsilverman during the Fall '10 term at Life Chiropractic College West.

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CHEM 1516 Biochem II Abby's Notes Part IV - Biochem II...

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