Midterm - 2 November 2015
•In class
•50 minutes
•Start 12:55 sharp
•55 multiple choice questions –1 point each
1 short answer-10 points
•from lecture 1a until end of lecture 6c
1
Carbohydrate/lipid/protein/alcohol
4/9/4/7 kcal/gram
17/37/17/29 kJ/gram
Note alcohol = ethanol
2
The new normal-Globe and Mail- 30
September 2012- parents do not
recognise when they and/or others
including kid(s) is/are overweight or
obese
Fat is the new normal
Lecture 5a
5 Oct. 2015
Lipids I
94/80
4
5
6
7
8
9
Overview of lecture 5a
1) Lipids defined
2) Functions of fats in foods
3) Structure, classification, presence in
food and function of:
a) fatty acids
b) triglycerides
c) phospholipids
d) cholesterol
4) Ingestion, digestion, absorption, transport,
metabolism and excretion
6) Functions of lipids-essential or not
10
1)Lipids defined p. 130
family of compounds that includes triglycerides,
(TG), phospholipids (PL) and sterols
other definition
water insoluble organic compounds made up of
C, H, and O like carbohydrates but less O
and therefore 9 vs 4 kcal/gm
11
2)Functions of fats in foods
•absorbing flavours and aromas of ingredients
•providing flavour of its own
•creamy and smooth mouth taste
•tenderizing and adding moisture
12
a)Triglycerides-fatty acids-structure,
classification, p.129-136
Organic acid
Saturated
14:0
Monounsaturated 18:1
Polyunsaturated 18:2 n-6
18:3 n-6 (gamma-linolenic acid)
18:3 n-3 (alpha-linolenic acid)
13
REPLACE WITH FIG 5-2
ACETIC ACID
14
Fig. 5-1, p. 140
p. 134
p. 134
p. 135
p. 135
p. 135
p. 135
21
a)Triglycerides-fatty acids-structure,
classification, p.129-136
Glycerol + 3 fatty acids make a triglyceride
Mixed triglycerides
22
23
24
Fig. 5-4, p. 137
Triglycerides continued
Triglycerides in food
Processed fat-fat manipulated mechanically or chemically
-chemical manipulation-hydrogenation-hydrogenation yields trans-fatty acids
26
Fig. 5-7, p. 138
Fig. 5-8, p. 139
A)- Triglycerides- in foods and function
In foods-triglycerides are most of the fat in our foods
(followed by sterols followed by phospholipids)
Function in our bodies-triglycerides are an energy
source and a major storage form of energy in our bodies
29
B) Phospholipids- structure,
classification, in foods and function
p. 136
Structure- 2 FATTY ACIDS (FA) and
polar head group-generally but exceptions
Classification
Choline-containing phospholipids
Ethanolamine-containing phospholipids
Phosphatidylserine
Phospatidylinositol
Sphingomyelin
30
Fig. 5-9, p. 140
Phospholipids continued
Foods- found naturally
Function p. 140
Membranes
Lipoproteins
Cell signalling
32
C) Sterols- structure, classification, in
foods and function p. 137
Structure-Ring structure
Classification-Sterols
33
Fig. 5-11, p. 141
Sterols continued
Foods- found naturally-cholesterol vs phytosterol
Function
Membranes
Lipoproteins
Bile acids
Hormones
Vitamin D
35
36
37
Fatty acids in foods regardless of free or
esterified
Function of fatty acids in food
essential in diet- linoleic acid and alpha-linolenic
acid-we cannot make these
38
Ingestion- mouth, tube or IV
Digestion of lipids p. 137-138
fats start out separated from enzymes in gi
(gastrointestinal tract)-why?\
goal of fat digestion
mouth digestion of fat
small intestine digestion of fat
39
Absorption of lipids p. 140-141
small molecules
short chain fatty acids
medium chain fatty acids
glycerol
direct to blood
larger molecules
monoglycerides
long chain fatty acids
micelles formed in intestine
micelles into intestinal wall cells
chylomicrons formed and released into lymph
E:\Media\Animations\chapter5\Absorption_of_Fat\051
7.html
40
Transport of lipids
p. 145-148
Lipoproteins-chylomicrons (CM)
(POST-PRANDIAL ONLY)
- very low density lipoprotein (VLDL)
- low density lipoprotein (LDL)
- high density lipoprotein (HDL)
- albumin
density change due to 2 factors
41
Lipoprotein metabolism
Chylomicrons- made in small intestine – acted on by
lipoprotein lipase in blood to give remnant particle which
is taken up liver VLDL (very low density lipoprotein)
made via liver
VLDL acted on by lipoprotein lipase in blood to give
remnant particle (intermediate density lipoprotein or IDL)
which is taken up by liver- liver puts out low density
lipoprotein (LDL)
HDL ( high density lipoprotein) and albumin made by
42
liver
Human lipid metabolism-in part only
Fatty acids oxidised in mitochondria to give
energy and water
Glycerol metabolised (enters glycolytic
path and then mitochondria)
Can also synthesise fatty acids,
triglycerides, phospholipids and sterols
43
Lipids excretion
Faeces-undigested and/or unabsorbed fat
Respiration (lipid metabolites -water and
CO2)
Urine-lipid metabolite (water)
Sweat-lipid metabolite (water)
Saliva?-intact fats and lipid metabolite
(water)
44
Lipids essential or not ?
p. 144-147
Yes-why ? healthy roles
45
Lipids- essential or not? yes- healthy
roles
1)insulation- healthy roles
protective layer in body to help
keep heat losses down
46
Lipids-essential or not? yes
Healthy roles
2)support and protection for internal organs
and bones
fat acts as support and cushioning for organs
and cushioning for bones
47
Lipids- essential or not? yes
Healthy roles
3)absorption of fat soluble vitamins fat soluble vitamins
cannot be absorbed without fat in the diet- why?
48
Lipids- essential or not? yes
Healthy roles
4)cell membranes cholesterol and phospholipids are
important in maintaining the structure
and hence function of cell membranes
what is a cell membrane?
49
Lipids- essential or not? yes
Healthy roles
5) gives structure to molecules
fatty acids give rise to triglycerides
and phospholipids
and cholesterol fatty acid complexes
structure of lipids in part dictates
their function
50
Lipids- essential or not? yes
Healthy roles
6)metabolically
-fat stored as fat- very efficient
-making fat from carbohydrate
and protein is not very efficient
-energy source-can store huge quanities of fat
51
Lipids- essential or not? yes
Healthy roles
7) impact on nutrient absorption
-gut motility is slowed
-slower rate of digestion
52
Fats - Unhealthy roles
Fad diets
no fat or less than 10 % of calories as lipid in diet
with all or mostly all of energy difference made
up with carbohydrate
53
Fat- Unhealthy roles
Fat to fat- obesity
-obesity- tough on joints, -may contribute
to arthritis
-elevates blood pressure- which may give
atherosclerosis and heart attacks and stroke
54
Fat- Unhealthy roles
Unhealthy roles-obesity continued
-elevates free fatty acids in the blood which may give
insulin resistance
-if excess fat in the diet this may crowd out other nutrient
classes
55