Midterm is 7 November in class
Lectures 1-6 inclusive-50 multiple choice-50 points
One 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 5
Lipid 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 classified
Polyunsaturated – 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 phospholipids
2 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)