Midterm is 7 November in classLectures 1-6 inclusive-50 multiple choice-50 pointsOne short answer question-10 points

Lecture 5- 10 October 2013

Most of this lecture taken from Chapters 5,7 of Rolfes et al(Understanding Normal and Clinical Nutrition(Nutrition 2104/2106 text)

Outline of lecture 5

Lipids classified

    -fatty acids    -saturation    -triglycerides    -phospholipids    -sterols

Outline of lecture 5

Lipids

    -digestion    -absorption    -transport

Outline of lecture 5

Lipids in the body

    -roles of triglycerides    -essential fatty acids

Outline of lecture 5

Preview of lipid metabolism

Outline of lecture 5Lipid Metabolism

    -fatty acid catabolism    -fatty acid anabolism    -triglyceride catabolism     -triglyceride anabolism    -cholesterol catabolism    -cholesterol anabolism    -phospholipid catabolism    -phospholipid anabolism    -regulation

More detailed comments

Lipids defined

a diverse group of compounds found in all living cells, insoluble in water but soluble in organic solvents such as ether, acetone and chloroform, and which include fats, oils, triacylglycerols, fatty acids, glycolipids, phospholipids and steroids, some lipids being essential components of biological membranes, others acting as energy stores and fuel molecules for cells.

Lipids classified

    -fatty acids            -straight hydrocarbon chain terminating

with a carboxylic acid group

   

Lipids classified

-fatty acids    -saturation

            -saturated-no double bonds between carbons in a fatty acid chain

             

Lipids classified

-fatty acids

   -diagram and partial list of saturated fatty acids                               -myristic acid 14:0                               -palmitic acid 16:0                               -stearic acid 18:0

Lipids classified

-fatty acids

monounsaturated-one double bond between carbons in a fatty acid chain

-diagram and partial list of mono-unsaturated fatty acids

                     -palmitoleic acid 16:1n-7                     -oleic acid 18:1n-9

Lipids classified

-fatty acids

-polyunsaturated- more than one double bond between carbons in a fatty acid chain         

-diagram and partial list of polyunsaturated fatty acids                                                    

-diagram of omega 3 vs omega 6 fatty acids                                                    

                                                  

Lipids classifiedPolyunsaturated – a partial list

Omega 6-linoleic acid 18:2-gamma-linolenic acid 18:3-dihomogammalinolenic acid 20:3-arachidonic acid 20:4

Omega 3-alpha-linolenic acid 18:3-eicosapentaenoic acid 20:5-docosahexaenoic acid 22:6

Lipids classified-cis and trans configurations

                                -diagram

                                                                         

Lipids classified

-triglycerides

            -three fatty acids attached to a glycerol backbone

            -diagram

                                                  

Lipids classified

                                                  

Lipids classified

-phospholipids

     example-choline containing phospholipids2 fatty acids and a choline head

group attached to glycerol

                    -diagram 

 

Lipids classified

-phospholipids

-ethanolamine containing phospholipids                    -2 fatty acids and an ethanolamine head group attached to

glycerol

            -phosphatidylinositol                    -2 fatty acids and an inositol head

group attached to glycerol

          

Lipids classified

-phospholipids

            -phosphatidylserine                    -2 fatty acids and a serine head

group attached to glycerol

            -sphingomyelin                    -one fatty acid and 2 other groups

attached to glycerol

  Lipids classified

-sterols            -cholesterol            -various hormones (eg estrogen,

testosterone) made from cholesterol

Diag chol

Lipids    -digestion

         -mouth            -lingual lipase                    -adults-minor role                    -infants- major role in digesting short

and medium chain fatty acids

Lipids    -digestion

            -stomach-no digestion

            -small intestine- pancreatic lipase-digests fatty acids from triglycerides

                                    -role of bile (figure 5-14, Rolfes)

Lipids-absorption            -glycerol, short and medium chain fatty

acids go directly into blood

            -monoglycerides and long chain fatty acids are formed into micelles which are moved into intestinal cells

                     in intestinal cells ultimately get phospholipids and  triglycerides formed into chylomicrons  which are moved into lymph - from lymph go into blood

 Lipids  -transport        lipoproteins            -fat protein particles-protein required to give water

solubility to lipids            -chylomicrons            -very low density lipoprotein            -low density lipoprotein            -lipoprotein (a)            -high density lipoprotein            -albumin

            -lipoprotein density affected by ratio of lipid to protein in a lipoprotein

Lipids in the body    -roles of triglycerides

               -primarily energy                -fat stores                -participates in carbohydrate metabolism                -protein sparing 

Lipids in the body

    -essential fatty acids                -linoleic                -alpha-linolenic 

Preview of lipid metabolism

                -fat is made into fat                -carbohydrate and protein can make fat

                  

Lipid Metabolism

    -fatty acid catabolism

                -fatty acids made into acetyl CoA                -acetyl CoA follows TCA cycle                -ATP is made

Lipid Metabolism   -fatty acid anabolism

                -acetyl CoA can be made into fatty acids                -omega 6 and omega 3 pathways                -ATP is used

                   

Lipid Metabolism

-triglyceride catabolism                 -to glycerol and fatty acids

-triglyceride anabolism                -fatty acids and glycerol make

triglycerides

Lipid Metabolism

-cholesterol catabolism                -largely made into bile

-cholesterol anabolism                -acetyl CoA made into cholesterol

Lipid Metabolism

-phospholipid catabolism                -made into glycerol, fatty acids and head

group (eg choline)

-phospholipid anabolism                -made from glycerol, fatty acids and head

group (eg choline)

Lipid Metabolism -regulation-closely linked to carbohydrate availability  

-lots of carbohydrate-favours fatty acid synthesis-due to lots of malonyl CoA which inhibits carnitine acyl transferase I that allows for transfer of fatty acids to carnitine for transport into mitochondria for oxidation to acetyl CoA- also if not enough carbohydrate for fatty acid synthesis but not so little that there is sufficient OAA-fatty acids are metabolised through the Krebs cycle (acetyl CoA from fatty acids joins with OAA to make citrate)

             -little carbohydrate-favours fatty acid catabolism to

ketones (acetyl CoA is converted to ketone as OAA is converted to glucose)