ch5 food and humans part i 2009
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Consequence ofanorexia nervosa
Ch.11 Food and humans
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Obese girl
- high risk ofdiabetes
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Under-nutrition
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Human skin can make ? under UV light
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Human skin can make vitamin D under UV light
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What are nutrition and nutrients?
1. Nutritionmeans the ways in which organismsobtain nutrientsformaintaining life.
2. Nutrients are substances that support life and
growth.
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What are nutrition and nutrients?
1. Nutritionmeans the ways in which organismsobtain nutrientsformaintaininglife.
2. Nutrients are substances that support life and
growth.
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Autotrophs, e.g. green plants.
Organisms who can make their own foodare calledautotrophs, (troph here means feeding).
They make their own food by photosynthesis
plus nutrients (minerals) from the soil.
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Autotrophs, e.g. green plants.
Organisms who can make their own foodare calledautotrophs, (troph here means feeding)
They make their own food by photosynthesis
plus nutrients (minerals) from the soil.
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Heterotrophs, e.g. humans
Organisms who cantmake their own foodare calledheterotrophs.
They must obtain their nutrients by eating foodmade
by other organisms.
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Heterotrophs, e.g. humans.
Organisms who cantmake their own foodare calledheterotrophs.
They must obtain their nutrients by eating foodmade
by other organisms.
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Manyjunk foods contains very little nutrients.Habitual eating ofjunk foodforyears may
lead to poor health due to the lack of nutrients.
Worst
of all,th
eyu
su
ally cont
ain lot
s ofsatu
rat
edlipids bad for ourhealth!
lipids include fats, oil, cholesterol,
steroids, wax, etc.)
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Comment on the health impact foreating this kind of fast food:
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Manyjunkfoods contains very little nutrients.Habitual eating ofjunk foodforyears may
lead to poor health due to the lackof nutrients.
Worst of all, they usually contain lots ofsaturated
lipids bad for ourhealth!
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The 7food substances
1. Carbohydrates
2. Lipids
3. Proteins
4. Water 5. Vitamins 6. Minerals
7. Dietary fibre
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The 7food substances
1. Carbohydrates
2. Lipids
3. Proteins
4. Water5. Vitamins 6. Minerals
7. Dietary fibre
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The 7food substances
1. Carbohydrates
2. Lipids
3. Proteins
4. Water5. Vitamins 6. Minerals
7. Dietary fibre
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The 7food substances
1. Carbohydrates
2. Lipids
3. Proteins
4. Water5. Vitamins 6. Minerals
7. Dietary fibre
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The 7food substances
1. Carbohydrates
2. Lipids
3. Proteins
4. Water5. Vitamins 6. Minerals
7. Dietary fibre
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The 7food substances
1. Carbohydrates
2. Lipids
3. Proteins
4. Water5. Vitamins 6. Minerals
7. Dietary fibre
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The 7food substances
1. Carbohydrates
2. Lipids
3. Proteins
4. Water5. Vitamins 6. Minerals
7. Dietary fibre
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Food substances
carbohydrates
()lipids
()proteins
()water
vitamins
()
minerals
()
dietary
fibre
()
protective food substances
()(to stay healthy)
primary food substances
()(essential to life)
inorganic
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Food substances
carbohydrates
()lipids
()proteins
()water
vitamins
()
minerals
()
dietary
fibre
()
protective food substances
()(to stay healthy)
primary food substances
()(essential to life)
inorganic
Q11.2
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The 7food substnaces: 4 primary food substances= ?
3 protective food substances = ?
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Food { food substances
Food (or foodstuff) = ? , e.g. . . ?seven food substances = ? , e.g. . . ?
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Food (= foodstuff) { food substances
seven food substances = . . . ?
Food /foodstuffse.g. hotdog, eggs, etc.
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Q11.3 Food { food substances
Food (= foodstuff)e.g.
Food sub
stancese.g.
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One of the 7 food substances:
(1) Carbohydrates
(carbo means carbon; hydrate means water)
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Food substances
carbohydrates
()lipids
()proteins
()water
vitamins
()
minerals
()
dietary
fibre
()
protective food substances
()(to stay healthy)
primary food substances
()(essential to life)
inorganic
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Ch.11 Quiz (1)
1)
The 4 primary
food substances = ?
2) the 3 protective
food substances = ?
3) For carbohydrates,
a. elements
making it up = ?b. ratio ofH:O = ?
c. basic unit = ?
4) The
3classes of
carbohydrates = ?
5)3
examples ofmono-saccharides = ?
6)3
examples ofdi-saccharides = ?
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What are carbohydrates?
It is made up ofcarbon (C),hydrogen (H) & oxygen (O)
What is the moleculeof water?
What is the moleculeofcarbohydrate?
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In each molecule ofcarbohydrate:
H:Oratiois 2:1
e.g.glucose C6H12O6
2 :1
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What are carbohydrates?
It is made up ofcarbon (C),hydrogen (H) & oxygen (O)
Ineach moleculeofcarbohydrate: H:Oratiois? :?
e.g.glucose C6H12O?
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each basic unit as one glucose molecule
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Three classes of carbohydrates
mono-sacch
arides di-saccharides
poly-saccharides
They are NOT drawn to the same scale)
mono- di- poly-
and
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The 3 classes of carbohydrates:
1. glucose2. fructose 3. galactose
4. sucrose 5. maltose6. lactose7. starch 8. cellulose
9. glycogen
mono-saccharides
di-saccharides
poly-saccharides
mono- di- poly-
and
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The 3 classes of carbohydrates:
1. glucose2. fructose 3. galactose
4. sucrose 5. maltose6. lactose7. starch 8. cellulose
9. glycogen
mono-saccharides
di-saccharides
poly-saccharides
mono- di- poly-
and
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The 3 classes of carbohydrates:
1. glucose2. fructose 3. galactose
4. sucrose 5. maltose6. lactose7. starch 8. cellulose
9. glycogen
mono-saccharides
di-saccharides
poly-saccharides
mono- di- poly-
and
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The 3 classes of carbohydrates:
1. glucose2. fructose 3. galactose
4. sucrose 5. maltose6. lactose7. starch 8. cellulose
9. glycogen
mono-saccharides
di-saccharides
poly-saccharides
mono- di- poly-
and
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Q11.4 The 3 types of carbohydrates:
1. glucose
2. fructose 3. galactose
4. sucrose 5. maltose6. lactose7. starch 8. cellulose
9. glycogen
mono-saccharide
di-saccharide
poly-saccharide
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disaccharides
glucose + fructose sucrose+ H2O
glucose + galactose lactose+ H2O
glucose + glucose maltose+ H2O
Carbohydrates
G-G / G-gal/ G-F
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disaccharides
glucose + fructose sucrose+ H2O
glucose + galactose lactose+ H2O
glucose + glucose maltose+ H2O
Q11.6 Carbohydrates
G-G / G-gal/ G-F
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Q11.7matching
MaltoseSucrose
Lactose
G-GG-gal
G-F
?
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Three classes of carbohydrates
mono-sacch
arides di-saccharides
poly-saccharides
They are NOT drawn to the same scale)
mono- di- poly-
and
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Matching
Monosaccharide
Disaccharide
polysaccharide
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Monosaccharides
Disaccharides
Polysaccharides
Themolecules
areinsingle and
separate saccharide
units
The moleculesarein
pairs of
mono-saccharide
units
The moleculesarein
groups (u3
saccharide units)
e.g.glucose,fructose,
galactose,etc.
e.g. maltose,lactose,
sucrose,etc.
e.g.starch,cellulose,
glycogen
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Monosaccharides
Disaccharides
Polysaccharides
Themolecules
areinsingle andseparate saccharide
units
The moleculesarein
pairs ofmono-saccharide
units
The moleculesarein
groups (u3saccharide units)
e.g.glucose,fructose,galactose,etc.
e.g.maltose,lactose,sucrose,etc.
e.g.starch,cellulose,glycogen.
Q11.5 The 3 types of carbohydrates:
3 f
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0
The 3 classes of carbohydrates:
1. glucose2. fructose 3. galactose
4. sucrose 5. maltose6. lactose
mono-saccharides
di-saccharides
1. sucrose = ? + ? ( = +)2. maltose = ? + ?3. lactose = ? + ?
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1
The 3 classes of carbohydrates:
Monosaccharide
Disaccharide
polysaccharide
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Molecule structures of polysaccharides
Glycogen Starch cellulose
and
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Molecule structures of polysaccharides
Glycogen Starch cellulose
and
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Examples of polysaccharides
glycogen()
starch(
)cellulose()
They are allpolymers of glucose
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Examples of polysaccharides
glycogen ()
starch (
)cellulose ()
They are allpolymers of glucose
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Examples of polysaccharides
glycogen ()- inanimals /fungi only
starch ()
- inplants only
cellulose()
- inplants only
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Examples of polysaccharides
glycogen ()- inanimals /fungionly
starch ()
- inplantsonly
cellulose()
- inplants only
c1asses common food sources importance
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poly-
saccharides( non-sweet
& some are
insoluble
in water)
glycogen
in animals andfungi
liverand
muscles
a food reserve, can be
broken down to formglucose tosupply
energy.
starch
in plants
Cereals,
bread,potatoes.
a food reserve, or
convertedto cellulosein plants formaking
cell walls.
cellulose
in cell walls or
plant fibres
orange and
vegetables
- a major component
ofdietary fibre for
humans
- for making cell walls
on plant cells
c1asses common
examples
food sources
importance
in human body
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The 7 food substances
(2) Lipids
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What are carbohydrates?
It is made up ofcarbon (C),hydrogen (H) & oxygen (O)
What are lipids?
It isalso made up of
carbon (C),hydrogen (H) & oxygen (O),but the ratio ofH : O is . . . .
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What are carbohydrates?
It is made up ofcarbon (C),hydrogen (H) & oxygen (O)
What are lipids?
It isalso made up of
carbon (C),hydrogen (H) & oxygen (O),but the ratio ofH : O is . . . .
Ch 11 Quiz (1) 8/12/08
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Ch.11 Quiz (1) 8/12/08
1)
The 4 primary
food substances = ?
2) the 3 protective
food substances = ?
3) For carbohydrates,
a. elements
making it up = ?b. ratio ofH:O = ?
c. basic unit = ?
4) The 3 classes of
carbohydrates = ?
5) 3 examples of
mono-saccharides = ?
6) 3 examples of
di-saccharides = ?
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Primary food substances
Lipids made up ofC,H,O
H:O
ratio
much greater than2
:1(moreH)
insoluble in water
b
ut solub
le in organic solvents, e.g. alcohol
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Structure of a lipid (fat) molecule
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Glycerol 3 Fatty acids
Four components
Lipid molecule Structure
=
A lipid molecule is E-letter like:
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Glycerol 3Fatty acids
Four components
Lipid molecule Structure
=
A lipid molecule is E-letter like:
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Which one(s) are unsaturated fatty acids below:
Oleic acid is a cis unsaturated fatty
acid that comprises 5580% of oliveoil.
Elaidic acid is a trans unsaturated
fatty acid often found in partiallyhydrogenated vegetable oils.
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Molecules having more regular structure tends tobecome asolideven at a high temp.
Which one is better for our health?
saturated lipid poly-unsaturated lipid
i i i i
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Molecules having more regular structure tends tobecome asolideven at a high temp.
Which one is better for our health?
saturated lipid poly-unsaturated lipid
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Obese girl
- high risk of
diabetes
Coronary heart disease:
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Coronary heart disease:coronaryarteryblockedbyfats
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An artery partly blocked by lipid plaque
Less bloodcan flows through this artery !
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Summary for lipids
A lipid molecule is E-letter like, made of
1 glycerol + 3fatty acid tails
Saturated lipids are poor to health
(may blockblood vessels)
Used as food reserve Used as heat insulator under skin
For making cell membrane (together with proteins)
Part of cell membrane
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Part ofcellmembrane
- made ofproteins and lipids
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Q11.8 Summary for lipids
A lipid molecule is E-letter like, made of
1 glycerol + 3fatty acid tails
Saturated lipids are poor to health
(may blockblood vessels)
Used as food reserve Used as heat insulator under skin
For making cell membrane (together with proteins)
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Exercise
Home web search for information about
trans fat (= unsaturated fat but . . .)
e.g.
http://www.citytech.cuny.edu/notransfatnyc/chines
e/faqs.html
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Cis fat (good) Trans fat (bad)
Oleic acid is a cis unsaturated fatty
acid that comprises 5580% of oliveoil.
Elaidic acid is a trans unsaturated
fatty acid often found in partiallyhydrogenated vegetable oils.
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Trans fat
Trans fat is a type ofunsaturated fat with
trans-fatty acid(s).
Some occurs naturally in very small amounts
in meat.
Some are produced chemically from plant oils in
industry to extend their shelf life.
T f
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Trans fat
They increase the risk of
coronary heart diseaseand raises our bad cholesterol level.
E l f d d f id
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Examples of good unsaturated fatty acids
= ? ????
d t t d f tt id
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good unsaturated fatty acids
;3
;6
DHA
F t d f d t t d f tt id
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Fats made from good unsaturated fatty acids
e.g. (1) nuts contain a lot of;3 and ;6 fatty acids!
The fats made from these fatty acids
help remove bad cholesterol!
e.g. (2) breast milk contains a kind of fatty
acid called DHA needed for healthy growth ofbrain and eyes!
F t d f d t t d f tt id
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Fats made from good unsaturated fatty acids
e.g. (1) nuts contain a lot of;3 and ;6 fatty acids!
The fats made from these fatty acids
help remove bad cholesterol!
e.g. (2) breast milk contains a kind of fatty
acid called DHA needed for healthy growth ofbrain and eyes!
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The 7 food substances
(3) Proteins
Aprotein molecule isa long chain(s) ofamino acids
B i it
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Basic units
of carbohydrate = saccharides, e.g. glucose
of lipid = glycerol + 3 fatty acids
of protein = amino acids(humans have 20 different kinds of amino acids)
carbohydrate lipid protein
B i it
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Basic units
of carbohydrate = saccharides, e.g. glucose .
of lipid = glycerol + 3fatty acids.
of protein = amino acids.(humans have 20 different kinds of amino acids)
carbohydrate lipid protein
P i f d b
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Primary food substances
Proteins
made up ofC,H,O,N (+S + P + . . .etc.)
extra elements = NSP . . .
A protein molecule
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A protein molecule
Has ? + ? + ? ,
in addition to C, H, O.
A protein molecule
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A protein molecule
Has N + S + P ,
in addition to C, H, O.
Building units of proteins
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Building units of proteins
amino acid
+
dipeptide
amino acid
amino acid+
amino acid
+
polypeptide
.
.
.
condensation
Polymers Polypeptides
Monomers
(repeating units)
Amino acids
Insulin (a protein hormone) consists of two polypeptides
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Insulin (a protein hormone) consists of twopolypeptides
Proteins
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8 essential
amino acids
12 non-essential
amino acids
Types ofamino acids
20 different
amino acids
Amino acids that cannotbe made by body
and mustbe obtained
from diet
Amino acids that canbe made from other
amino acids
Proteins
8 essential amino acids
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8essential amino acids
Humans cant live without the their continuous
supply from food because
our bodies cant make them!
(There is no harm if you diet does not contain
non-essential amino acids. Why?)
8 essential amino acids
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8essential amino acids
Humans cant live without the their continuous
supply from food because
our bodies cant make them!
(There is no harm if you diet does not contain
non-essential amino acids. Why?)
It is because my body can convert (change)
other amino acids to the missing ones!
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forgrowth andrepair.
provide energy ifcarbohydratesandlipids
storedareused up.
Functions of proteins:
formaking enzymes, insulin,etc.
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forgrowth andrepair.
provide energy ifcarbohydratesandlipids
storedareused up.
Functions of proteins:
formaking enzymes, insulin,etc.
Deamination of amino acids (AA)
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Deamination ofamino acids (AA)
Excess proteins cant be storedin our bodies.
Theyformamino acids which are broken down in
the liver by deamination to form ammonia (NH3).
Deamination in liver
= excess amino acids NH3
+ carbohydrate
(This ammonia will then be converted to the
less toxic urea for excretion)
Deamination breaks down excess amino acids in liver:
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Deamination breaks down excess amino acids in liver:
Q11.9
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Deamination breaks down excess amino acids in liver:
Whats wrong:
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What s wrong:
Excess proteins deamination forms urea
Whats wrong:
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What s wrong:
Excess amino acids deamination forms urea
Whats wrong:
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What s wrong:
In the liver,
excess amino acids deamination forms urea
Whats wrong:
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What s wrong:
In the liver,
excess amino acids
deamination
forms ammonia (NH3)
Whats wrong:
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What s wrong:
In the liver,
excess amino acids
deamination
forms ammonia (NH3) + carbohydrates
Whats wrong:
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What s wrong:
In the liver,
excess amino acids
deamination
forms ammonia (NH3) + carbohydrates
This ammonia is very toxic and is mostly
converted to urea less toxic.
The carbohydrates can be used by the body.
Excess protein from diet
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digested to excess amino acids
amino
acids
carbohydrate+
ammonia
Excess
amino
acids
Liver
deamination in liver
Urea is made in our liver
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ammonia urea
Excess
amino
acids
urea
Liver
(This is NOT deamination)
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Starvation caused
Kwashiokor inchildren(,
)
Kwashiokor children have
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111lymph vessel
too much tissue fluid in bellies
Kwashiokor is a protein deficiency disease
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p y
Children in poor countries are lack of protein in
their diets lack of meat, eggs, milk, etc.
Their blood contains too little protein so that more
water leaks out from their capillaries
to form excessive tissue fluid in theirswollen bellies .
Kwashiokor is a protein deficiency disease
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p y
Children in poor countries are lack of protein in
their diets lack of meat, eggs, milk, etc.
Their blood contains too little protein so that more
water leaks out from their capillaries
to form excessive tissue fluid in theirswollen bellies.
Concept map:primary food substances
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Energy value of3 primary food substances
(purified)
Which food substances are being burnt to provide
energy for running?
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energy for running?
Food and Energy
kJ = kiloJoule
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gy
Food substanceEnergy value
(kJ/g)
Pure carbohydrates 17
Pure proteins 18
Pure lipids 39
Lipids has the highest energy valueLipids has the highest energy value
about double of same mass of
carbohydrate and protein
about double of same mass of
carbohydrate and protein
Food and Energy
kJ = kiloJoule
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gy
Food substanceEnergy value
(/g)
Pure carbohydrates
Pure proteins
Pure lipids
Lipids has the highest energy valueLipids has the highest energy value
about double of same mass of
carbohydrate and protein
about double of same mass of
carbohydrate and protein
Food and Energy
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gy
How much energy is there in
various foodstuff ?
The energy value of a foodstuff is
determinedb
y its composition
Food
(100g)
Rice (cooked)
Energy
value
(kJ)
434.5
Carbohydrates
(g)
23
Proteins
(g)
2.2
lipids
(g)
0.1
Water
(g)
74
Total energy in 100g rice = (23x17+ 2.2x18+ 0.1x39)kj
Q11.10 Calculate Food and Energy
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120
How much energy is there in
various foodstuff ?
The energy value of a foodstuff is
determinedb
y its composition
Food
(100g)
Rice (cooked)
Energy
value
(kJ)
434.5
Carbohydrates
(g)
23
Proteins
(g)
2.2
lipids
(g)
0.1
Water
(g)
74
Total energy in 100g rice = (23x17+ 2.2x18 + 0.1x39)kj
1. The energy value was measured in calories
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but is now in kilojoules (kj).
2.O
rder of preferencefor energy supplyin our bodies:
carbohydrates > lipids > proteins.
3. However, our brain cells strictly depends on
glucose only for energy.
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4. In case offastingor starvation,proteins in ourmuscles would be broken down
to yield energy.
5. Vitamins, minerals and waterhave no energy
value.Dietary fibre has energy value to herbivores
only.
Johns on slim plan
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How much lipids are broken down in these 2 days?
Energyintake from
food (kJ)
Break down lipids (kJ)by doing exercise
yesterday 10 6
today 3 12
total 13 18
Johns on slim plan
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How much lipids are broken down in these 2 days?
Energyintake from
food (kJ)
Break down lipids (kJ)by doing exercise
yesterday 10 6
today 3 12
total 13 18
+4 kJ
-9 kJ
Slim plan
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Fat burn . ..
Break down oflipids by respiration . . .
Ch.5 Food and Humans Ex. P. 30 Q.9
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9. Some vegetarians eat plant foods only.
a From the nutritional point of view, explain two
advantages of having a diet rich in plant foods
over that with little plant foods. (4 marks)
bMost plant foods have a low protein content.
Suggest a plant food that can provide a lot of
protein to the vegetarians.(1 mark)
Ch.5 Food and Humans Ex. P. 30 Q.9
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9. Some vegetarians eat plant foods only.
a From the nutritional point of view, explain two
advantages of having a diet rich in plant foods
over that with little plant foods. (4 marks)
bMost plant foods have a low protein content.
Suggest a plant food that can provide a lot of
protein to the vegetarians. (1 mark)
Ans. Soya beans