For humans , starch constitutes a digestible carbohydrate , while cellulose is one of the indigestible carbohydrates that form a large part of the fiber , bulk , or roughage of our diets .Grass , leaves , and other plant material all of which are indiges - PowerPoint PPT Presentation

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For humans , starch constitutes a digestible carbohydrate , while cellulose is one of the indigestible carbohydrates that form a large part of the fiber , bulk , or roughage of our diets .Grass , leaves , and other plant material all of which are indiges

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Title: For humans , starch constitutes a digestible carbohydrate , while cellulose is one of the indigestible carbohydrates that form a large part of the fiber , bulk , or roughage of our diets .Grass , leaves , and other plant material all of which are indiges


1
9. Carbohydrates Chapter 16
2
CARBOHYDRATES
  • Contain C, H, O only
  • CXH2YOY CX(H2O)Y
  • i.e hydrates of carbon
  • most common names end in '-----ose'

3
CarbohydratesGeneral Structural Features
  • Usually 5/6 membered rings with C and one O
  • Many -OH groups ? water soluble
    (simple ones )
  • ? easily broken down for energy
  • (already partly
    'oxidized')

4
From Monosaccharides to Polysaccharides
  • The root sacchar- comes from the Latin saccharum,
    "sugar".

A monosaccharide is the smallest molecular unit
of a carbohydrate. Glucose, the prototypical
monosaccharide, is the most abundant organic
molecule on earth.
5
  • A disaccharide is a molecule formed from a
    combination of two monosaccharides, eg. sucrose
  • A polysaccharide is a molecular chain (maybe
    branched) of hundreds / thousands of mono-
    saccharides, eg. cellulose

6
Common Carbohydrates
Formula
Carbohydrate
Monosaccharides, C6(H2O)6 Glucose (blood sugar,
grape sugar, dextrose) C6H12O6
Fructose ( levulose )
C6H12O6 Galactose C6H12O6
Disaccharides, C12(H2O)11 Sucrose (table
sugar,beet sugar, cane sugar)
C12H22O11 Maltose (malt sugar)
C12H22O11 Cellobiose
C12H22O11 Lactose (milk sugar )
C12H22O11 Polysaccharides,
Cx(H2O)y Starch Cellulose
7
Glucose a 2,3,4,5,6-pentahydroxy hexanal
C6H12O6 a(aldo)hexose
open chain
cyclic (6 mem. ring
pyran)
8
Glucose single then soluble
9
Polysaccharides the Glycosidic Linkage
glycosidic linkage
monosaccharides
starch 1,4 linkages cellulose
10
STARCHES
  • Plant
  • ?Amylose -straight chain (200 ?-D glucose
    units)
  • ? Amylopectin - branched every 25 units
    (1000 ?-D glucose units)
  • ? Dextrins -partial breakdown of amylopectin
    (food additives , paste , fabric finishes )
  • Animal
  • ? Glycogen
  • -branches every12 units
  • -short-term energy in body (liver muscle).

11
More Branching Faster Breakdown
Amylopectin Glycogen
12
Amylose Helical Structure
  • Left hand helix (partial)

13
Iodine test for Starch
  • Helical structure of amylose holds the I3- ion
    linear cellulose does not

14
Carbohydrates The Most Common Energy Source
  • Chemical Breakdown / Reaction Digestion
  • Complex ? Dextrins ? Simple ? Mono-
  • ? acetate(2C) CO2 H2O Energy
  • NB. can be reversed, ie. glucose ? ? glycogen

H2O
H2O
H2O
(glucose)
(starch)
O2
15
Starch Breakdown / Digestion
Complex Dextrins Small
Mono-
16
Energy Sources   Instant Blood
sugar(glucose) 1g/L or 20Cal or
30mins.   Short Term Liver/Muscles(glycogen)
325g or 6 hrs. the more muscle,
the more glycogen any excess is converted into
fat   Long Term Fat(adipose tissue) 20kg
or 35 days
17
Nutritional / Dietary Carbohydrates   Starch -
the digestible carbohydrate(for humans)  
Simple - mono-/disaccharides, eg. sugars
Complex -seeds/roots of plants,
eg. grains(pasta), corn, potatoes, rice
Recommended - at least 55 of our Caloric
intake (10
sugar 45 complex) N A average - 20
sugar 25 complex!
18
Cellulose - indigestible carbohydrate for
humans     Soluble(pectins/gums) -
fruits(apples), grain husks
(oat
bran) Insoluble(fiber/bulk/roughage) - potato
skins, apple
peels, celery, lettuce     Recommende
d - 30g/day NA average - 15g/day
 
19
What is Dextrose?
  • Dextrose (Blood sugar) is the form of glucose
    that rotates the plane of polarized light in a
    clockwise direction.

20
What is invert sugar?
  • Hydrolysis of ()sucrose (table sugar) produces
    equal amounts of ()glucose and (-) fructose
    (levulose).
  • But, fructose optical rotation is larger
    (negatively) than glucose rotation is positively.
    Hence, the resulting solution is levorotatory
    (-).
  • Thus, start with only () then get (-) after
    hydrolysis-so the net result of hydrolysis is
    inversion of the direction of the optical
    rotation
  • Honey is mostly invert sugar ie an equal mixture
    of glucose and fructose

21
Sucrose -gt Glucose Fructose (Invert)
sucrose(66)
sucrase (invertase)
D-glucose(52) (dextrose)
D-fructose(-92) (levulose)

22
Maltose the basic unit of Starch
?(down) - linkage
requires maltase (humans gt yes)
23
Cellobiose the basic unit of Cellulose
?(up) - linkage
requires cellobiase (humans gt no)
24
Why Dietary Fibre? It's Indigestible!
  • Beneficial statistical correlations for colon
    cancer, obesity, diabetes, heart disease.
  • Acts as a sponge for water and other substances
  • Functions as a physical 'cleaner'
  • Soluble - can help lower cholesterol levels
  • reduces rate of glucose absorption
  • Insoluble - fills you up ?eat less fat
  • 'cleans' folds in intestinal walls
  • no physical damage to intestinal
    walls
  • adsorbs/removes many 'nasties'

25
Human Exploitation of Cellulose
Cellulose is a major component of grass, leaves,
wood, cotton(produced by photosynthesis). World
Biomass Production 1011 tons annually Present
Humans benefit indirectly by allowing
ruminants(cows, sheep) to digest cellulose
and convert it into protein which we eat.
26
Enzyme Substrate like a Lock Key
Enzymes are huge protein molecules with intricate
but well-defined shapes. They are the catalysts
that bring about all the chemical reactions in
our bodies. For effective reactivity the molecule
must fit into the convolutions of the shape of
the enzyme. Much like a key must fit the tumblers
of a lock.
27
Lactose Intolerance
Lactase is the enzyme that specifically breaks
the ?-1,4- linkage of lactose to produce
D-galactose and D-glucose. Infants have a highly
active form but 70 of adults have some lactase
deficiency.  If lactose is not cleaved in small
intestine it passes to the colon and 1) absorbs
water or 2) is degraded by bacteria, resulting in
cramps, diarrhea, etc.  About 10 of NA adults
permanently lose their lactase compared to 3 of
Danes and 97 of Thais.
28
Lactose (milk sugar) a disaccharide
lactase H2O
D-galactose
D-glucose
4-O-(?-D-galactopyranosyl)-D-glucopyranose
29
Solving the problem
  • Buy it!

30
Sweetness Index
Substance Relative
Sweet Taste
Lactose
0.16 Maltose
0.33 Glucose
0.74 Sucrose
1.00 Fructose
1.73
(NB. Glucose Fructose Honey or Invert Sugar)
Aspartame
180 Saccharin
300
31
Sucrose lots of OHs high water solubility
?-D-glucopyranosyl-? -D-fructofuranoside
32
Refined Sugar
NA sugar consumption 1kg
(1750) (annually/person)
50 kg(1990) Per day 50,
000/365 136 grams per person/day
world-wide production gt80 million tons
(60 from cane 40 from beets)
Dangers
dumps too much
glucose into blood too quickly all other
nutrients(vitamins, minerals) are removed
33
Everybodys Comfort Food !
Wow !
34
An Informative Label ?! ..Not Likely
35
Refined Sugar in some Processed Foods
Food
Sugar
Jello
83 Coffeemate
65 ShakeN Bake
50 Salad Dressing
30 Ketchup
29 Ice cream
21 Peaches(in syrup)
18 Peanut butter
9 Coca Cola
9
36
Sugar in human blood
  • Blood sugar is glucose (dextrose)
  • It is the only fuel for the brain and the Central
    nervous system (CNS) and supplies the E for basal
    metabolism
  • For continuous supply, a concentration of 0.06 to
    0.11 weight is maintained

37
Control of Blood Sugar (normal 100mg/dL)
Too Low
(lt75mg/dL) hypoglycemia(fainting)
Too High
(gt150mg/dL) hyperglycemia/diabetes
38
Urine test for diabetes
  • Above 0.16 weight in blood , glucose seeps
    through the kidneys into the urine

39
Diabetes Mellitus
Type I (insulin dependent) 10 of all diabetics
(juvenile onset)
Type II (non-insulin dependent insulin receptors
in
cells have become inactivated by excess use of
sugar) 90 of all diabetics (formerly called
adult onset but now found in 10-12 year
olds!)
NB. Diabetes is
1) second only to trauma for leg amputation
2) leading cause of blindness in adults over 20
3) leading cause of kidney failure
4) almost triples risk of heart attack or
stroke
40
Type 1 Diabetes
  • Body produces virtually no insulin
  • Thus insulin needed for treatment
  • Absence of insulin causes uncontrolled lipolysis
    of fat and severe wasting of body tissues,
    eventually resulting in death

41
Living with Type 2 Diabetes
  • Body makes too little insulin or its effect is
    resisted
  • In some cases insulin is needed
  • sometimes controlled with a reduced sugar diet
  • Loss of weight will cause an increase in the
    number of insulin receptors, hence improved
    condition

42
Canadians Discover Insulin (1921)
  • Frederick Banting and his assistant Charles Best
    isolated insulin from the pancreas of dogs
    (canine insulin) and administered it to Type 1
    patients
  • Nobel Prize awarded to Banting and McLeod for
    this work

43
Structural Differences
  • Porcine canine insulin are identical and have
    50/51 amino acids in common with human insulin
  • Bovine insulin and human insulin have 48/51 amino
    acids in common
  • Thus porcine insulin most often used

44
Source of Human Insulin
  • Patients who are allergic to these can now get
    cloned Insulin marketed as the Drug Humulin

45
Synthesis of Human Insulin
  • Saran Narang (NRC Ottawa) 1930-2007
  • Synthesised the proinsulin gene
  • Enabled mass production of Humulin
  • Via recombinant DNA
  • Insulin is a protein
  • 51 amino acids
  • DNAgtRNAgtprotein

46
Other molecules with sugar type structures
47
Fake Fats
Simplesse - from egg white or milk proteins
   Emulsified starch - in
Hellmans light mayonaisse   
Emulsified protein - gelatin water   
Olestra (200 million, by ProctorGamble) -
may cause cramps/diarrhea(?dehydration)
reduces absorption of vit. A, D, E, K (fat-
soluble
vitamins) into body
not digested available in USA since 1996 must
carry warning label not legal in Canada
48
Olestra Sucrose Octa Palmitate
Not OH but OR (R OC-C16 (sat.
palmitate)
NB. At least 6OHs esterified to be non-metabolized
49
Olestra Indigestible !
Olestra
a Triglyceride
50
Chitin (an exoskeleton polymer)
?(D)-glucosamine
51
Glucosamine
  • A simple amino sugar C6H13NO5.
  • Produced commercially by hydrolysis of crustacean
    exoskeletons
  • Used in treatment of osteoarthritis
  • Sold as a salt-either HCl or sulfate
  • Typical dose up to 1.5gr/day

52
Glucosamine (3-aminoglucose)
53
Blood Typing by Glycoprotein Antigens
Type A

acetylgalactosamine-galactose-acetylglucosamine-PR
O
fucose
Type B lactose-galactose-acetylglucosamine-PRO

fucose
Type O galactose-acetylglucosamine-PRO
fucose
54
Chocolate - Covered Cherries
Cherries are first coated with sugar
paste(sucrose) sucrase(enzyme). After hardening
they are dipped in chocolate and stored. After
1-2 weeks the sucrose is hydrolyzed/split by the
sucrase into glucose fructose which dissolves
easily in the cherry juice.
Chemistry is Everywhere !
55
3 Cherry Blossom Questions
  • One ingredient is called invertase .What is
    another name for this?
  • Another ingredient is soy lecithin. What function
    does it serve?
  • Another ingredient is modified vegetable oil
    How has it been modified?

56
Problem set 3
  • Chapt 13 1
  • Chapt 151,8,9,10,11,25,29
  • Chapt 161,9,11,12,18
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