ch5 food and humans part i 2009

8/3/2019 Ch5 Food and Humans Part I 2009

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1

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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1. Carbohydrates

2. Lipids

3. Proteins

4. Water5. Vitamins 6. Minerals

7. Dietary fibre


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1. Carbohydrates

2. Lipids

3. Proteins


7. Dietary fibre


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1. Carbohydrates

2. Lipids

3. Proteins


7. Dietary fibre


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1. Carbohydrates

2. Lipids

3. Proteins


7. Dietary fibre


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1. Carbohydrates

2. Lipids

3. Proteins


7. Dietary fibre


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1. Carbohydrates

2. Lipids

3. Proteins


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

()


()(to stay healthy)



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

()


()(to stay healthy)



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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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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9. glycogen

mono-saccharides

di-saccharides

poly-saccharides

mono- di- poly-

and


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9. glycogen

mono-saccharides

di-saccharides

poly-saccharides

mono- di- poly-

and


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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


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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4

9

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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5

0



4. sucrose 5. maltose6. lactose

mono-saccharides

di-saccharides

1. sucrose = ? + ? ( = +)2. maltose = ? + ?3. lactose = ? + ?


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5

1


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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glycogen ()

starch (

)cellulose ()

They are allpolymers of glucose


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glycogen ()- inanimals /fungi only

starch ()

- inplants only

cellulose()

- inplants only


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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 lipids?

It isalso made up of

carbon (C),hydrogen (H) & oxygen (O),but the ratio ofH : O is . . . .


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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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Q11.9


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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



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





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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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

ch5 food and humans part i 2009

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