Carbohydrates

1
Carbohydrates
2
I make a concerted effort to eat 5 or more fruits
and/or vegetables per day.

• Strongly Agree
• Agree
• Neutral
• Disagree
• Strongly Disagree

3
When selecting vegetables, I seek to eat several
different types per day to increase variety.

• Strongly Agree
• Agree
• Neutral
• Disagree
• Strongly Disagree

4
Carbohydrates sugar containing compounds

• Widely distributed in plants, some in animals
• made of Carbon, Hydrogen, and Oxygen
• Abbreviated as CHO
• Made during photosynthesis
• 6CO2 6H20 --gt (CH2O) 6 6O2

5
Photosynthesis

• H acceptor H donor --gt Reduced acceptor with O2
  release(from water)
• Some bacteria can use H2S as the H donor

6
Photosynthesis requires all but one of the
following to produce glucose. Identify the
incorrect agent

• CO2
• H2O
• O2
• H acceptor
• H donor

7
Size of Carbohydrate Polymer

• Monosaccharide one sugar unit
• Disaccharide two sugar units
• Oligosaccharide three to ten(6) sugar units
• Polysaccharide 10 (6) or more sugar units

8
Monosaccharides

• Aldoses aldehyde group is present
• H
• R-- C O
• A sugar containing an aldehyde group is called an
  aldose

9
Monosaccharides

• Ketose a sugar that contains a ketone group
• R
• C O
• R
• A sugar that contains a ketone group is called a
  ketose

10
If there is a O emanating from an internal
carbon on a sugar, we refer to this as a..

• Aldose
• Ketose
• Lipid
• Aldehyde

11
Monosaccharides

• Trioses 3 carbons long C3H6O3
• Tetroses 4 carbons long C4H8O4
• Pentoses 5 carbons long C5H10O5
• Hexoses 6 carbons long C6H12O6

12
What is the ratio of C to H to O in Carbohydrates?

• 212
• 123
• 146
• 121
• 221

13
Common Monosaccharides

• Glucose Hexose, aldose
• Fructose Hexose, ketose
• Galactose Hexose, aldose
• Ribose Pentose, aldose

14
Common Disaccharides

• Sucrose glucose fructose
• Lactose glucose galactose
• Maltose glucose glucose

15
Galactose is a hexose, Ketose

• True
• False

16
Common methods of showing sugar structure

• stick method
• straight chain
• Haworth thermodynamic model
• boat and chair forms, from x-ray diffraction

17
Stereo-isomerization

• Asymmetric carbons make stereoisomers possible
• Carbons attached to 4 different groups
• n number of asymmetric carbons
• 2 n number of stereoisomers possible
• For glucose, how many stereoisomers are possible?

18
If a pentose had 3 asymmetric carbons, how many
potential isomers would you predict?

• 2
• 4
• 8
• 16

19
Isomerization

• Well Discuss three types
• D L
• alpha and beta
• epimers

20
D L Isomers

• Based on the orientation of the OH and H adjacent
  to the terminal primary alcohol or carbon
• D dextrarotatory rotates polarized light to the
  right(most Glucose is D)
• L Levarotatory rotates polarized light to the
  left
• When D L present in equal amounts no optical
  activity

21
Alpha and Beta Anomers

• Ring structure of an aldose is a hemiacetal
• Ring structure of a ketose is a hemiketal
• In D glucose, mutarotation occurs at C1 so OH and
  H rotation occurs
• alpha one with greater rotation

22
At C 1 in Glucose, the OH group can rotate from
one side to the other. The placement of OH that
causes the greatest rotation is called the _____
form.

• beta
• alpha
• gamma
• delta
• L

23
Epimers

• Important Glucose isomers in nutrition
• alpha, D Galactose at C4
• alpha, D mannose at C2

24
What is the name of the epimer of Glucose where
OH group at C4 has a different orientation than
Glucose?

• Gulose
• Mannose
• Sucrose
• Galactose

25
Pentoses 5 Carbon Sugars

• Ribose and Deoxyribose RNA DNA
• Adenosine Phosphate ----gt AMP
• Adenosine is also a vasodilator in head
• Fits into a receptor in the cell membrane
• Relationship to caffeine and headaches?

26
Hexoses

• D sugars are important in nutrition
• D glucose, D fructose, D galactose, D mannose
• Abnormalities associated with genetic inability
  to metabolize D galactose
• Galactosemia autosomal recessive disorder
• 1/60,000 among caucasians in US hepatomegaly,
  cataracts, retardation

27
Fructose

• Ketohexose
• forms a 5 member ring (a furan Vs a Pyran)
• absorbed by body but metabolized to glucose in
  liver before it is usable by the body
• commonly found in fruit, honey

28
Fructosuria Hereditary Intolerance

• Autosomal recessive
• Two potential problems
• A. inactive fructokinase
• alternate pathway to fructose-6 phosphate
• no damage asymptomatic
• B. inactive Fru-1 P aldolase
• build-up of Fru-1-P
• GI problems, liver and kidney dysfunction and
  failure

29
Fructosuria Onset and treatment

• Onset After solid foods are introduced
• Treatment Avoid fructose in the diet
• No sucrose, fructose

30
When would fructosuria show up in a persons
life? When they consume____

• breast milk
• solid foods such as fruit
• Formula with sucrose as CHO
• 1 and 2
• 2 and 3

31
Glucose

• Major compound of metabolism
• Used by all tissues for energy
• Some tissues use ONLY glucose
• lens of eye, nervous tissue, RBCs, parts of
  kidney
• Highly regulated in the blood because of its
  importance

32
Glucose normal and abnormal

• normal fasting blood glucose 75-105 mg/dl plasma
• Hypoglycemia below that
• fasting hypoglycemia
• reactive hypoglycemia
• too much insulin moves glucose out of blood
• Hyperglycemia above that

33
Diabetes Type 1 and Type 2

• Type 1 no insulin produced
• Beta cells in pancreas killed by autoimmune
  activity
• Genetics Vs environment
• 25 of identical twins develop Type 1

34
Diabetes Type 2

• Type 2
• non-functional insulin
• insulin receptor site down regulation
• upregulation occurs with weight loss and exercise
• many people can control with diet and exercise
• many people take oral hypoglycemic agent such as
  Diabanese increases insulin secretion
• Some people take insulin

35
Sugar Derivatives Alcohols

• Xylitol pentose sugar alcohol
• found naturally in fruits and vegies
• raspberries, strawberries, lettuce, cauliflower
• name comes from adding an alcohol
• used as an alternative sweetener
• available from hemicellulose, a fiber that is
  found in almond shells, hardwood, oat hulls.
• Cariostatic Properties decreases risk of decay

36
Sugar Derivatives xylitol

• 2 field studies
• French Polynesia 32 months
• Hungary 36 months
• 2 groups A control brushed with Fluoride
  toothpaste
• B Test A plus 14-20 grams/day of xylitol in
  hard candy
• Test group had 45-50 fewer cavities that
  Control group

37
Xylitol mechanism of action

• Bacteria do not ferment xylitol and it may be
  toxic to some oral bacteria
• Stimulates flow of saliva in the mouth
• pH doesnt have the chance to drop too much
• 2.4 to 4 Kcal/ gram not as well absorbed
• sweetness equivalent to fructose, sweeter than
  sucrose

38
Other sugar alcohols

• Ribitol not used as a sweetener
• produced by reduction of ribulose, a ketopentose
• component of Riboflavin, a B vitamin
• Sorbitol pentose alcohol
• 50 as sweet as sucrose
• poorly absorbed small effect on blood glucose

39
Which of the following is used to sweeten some
chewing gums and has cariostatic properties?

• Ribitol
• Sorbitol
• Xylitol
• Sucrose
• Glycogen

40
Sugar Acids

• Aldonic Acids
• Aldehyde at C1 oxidized to COOH, carboxylic acid
• First step in pentose formation in hexose
  monophosphate shunt
• used to form ribose for RNA and deoxyribose for
  DNA

41
Sugar Acids

• Uronic Acids
• in other animals first step in vitamin C
  formation
• Alternate pathway in metabolism of Glucose with
  no ATP produced
• COOH at C6

42
Sugar Phosphates

• Metabolically active forms of CHOs
• Intermediates in metabolic pathways
• found in small quantities because they are
  turning over very quickly
• Why phosphorylated?
• they release energy when phosphate is removed to
  drive reactions
• they cant pass through cell membranes so
  metabolically active molecules stay inside cells

43
Other sugar derivatives

• Amino sugars
• Hexosamines glucose amines
• constituent of hyaluronic acid found in loose
  connective tissue
• Proteoglycan
• Heparin oligosaccharide attached to a
  polypeptide backbone
• anticlotting properties

44
Other sugar derivatives

• Glycoproteins
• MW 15000 to 1 million
• mono or oligosaccharide covalently bound to
  proteins
• structural component of cell walls, collagen,
  elastin, bone matrix, fibrins
• Fibrin is a glycoprotein involved in the clotting
  of blood. It is a fibrillar protein that is
  polymerized to form a "mesh" that forms a
  hemostatic plug or clot (in conjunction with
  platelets) over a wound site.
• lubricant mucins, mucous secretions
• transport molecule for vitamins, lipids
• antifreeze in antarctic fishes

45
Other Sugar Derivatives

• Glycolipids (sphingolipids)
• fatty acids with CHO
• structural components of membranes and neural
  tubes
• non-polar lipids embedded in cell membrane while
  polar sugar sticks out into watery environment

46
Sugars are only used as an energy source in the
body and have no other uses.

• True
• False

47
Disaccharides

• Formed from condensation reactions
• monosaccharides form glycosidic bonds
• Glucose aldehyde in ring structure forms a
  hemiacetal which is reactive
• reacts with the OH from another sugar to form a
  1,4 glycosidic bond
• Alpha if sugar is an alpha sugar, beta if beta
  sugar
• 1,6 glycosidic bonds also possible

48
Nutritionally important Disaccharides

• Sucrose glucose and fructose
• Maltose glucose and glucose
• Lactose glucose and galactose

49
Sucrose Most widely distributed of Disaccharides

• Table sugar sources are sugar cane and sugar
  beets
• Relatively pretty sweet because fructose is in an
  accessible location and fructose is very sweet.
• Non-reducing sugar no free aldehyde or
  hemiacetal to condense with

50
Sucrose called invert sugar

• When hydrolyzed optical rotation changes
• sucrose 66.5
• glucose 52.7
• fructose -92.4
• net optical activity -40 therefore inverts from
  positive rotation to negative rotation

51
Maltose

• Found at seed stage of plant lifecycle
• Starch in seed is broken down during germination
• provides energy for sprouting
• Found in digestion when starch is digested to
  smaller molecules
• Also found in beer making where starch of grain
  is broken down or malted

52
Lactose milk sugar

• Principle CHO of cows milk
• Lactase enzyme that digests Lactose in GI tract
• Lactose-----gt Glucose and Galactose
• Lactose Intolerance or Lactase Deficiency
• Both mean the person is unable to digest Lactose
  because they cant produce Lactase

53
Lactose Intolerance

• 3 forms
• Primary means the person has lost the ability to
  produce lactase because of genetics. Production
  ok until weaning and then the person gradually
  loses ability to produce. Common in some
  equatorial populations not as common in northern
  climates
• Secondary due to infection of GI tract clears
  up when infection is dealt with
• Congenital at birth very rare

54
Lactose Intolerance Symptoms and Diagnosis
Treatment

• Symptoms GI track distress, diarrhea.
• Dx Intestinal Biopsy and enzyme assay, invasive
  and not often done
• lactose tolerance test
• 50 grams lactose given
• Blood glucose checked at 0, 15, 30, 60 and 120
  minutes
• Plasma Glucose increase of 30 mg/dl normal
• 20-30 questionable lt 20 lactase deficiency
• Treatment

55
Which of the following is also called invert
sugar?

• Glucose
• Maltose
• Lactose
• Sucrose
• Galactose

56
Congenital lactose intolerance

• Is very rare
• Has its onset in adulthood
• Has its onset in infancy
• 1 and 2
• 1 and 3

57
Galactosemia

• Inability to convert Galactose to Glucose
• Autosomal Recessive
• 1 in 60,000 caucasian births
• Build up of galactose derivatives causing damage
  to liver, brain, kidneys and eyes
• Onset milk consumption
• Treatment avoid lactose

58
Polysaccharides

• Homopolysaccharides all the same sugar in the
  molecule
• Starch and Glycogen Cellulose
• Heteropolysaccharides two or more sugars in
  molecule
• Hemicellulose glucose, ribose, galacturonic acid

59
Cellulose

• Is a homopolysaccharide
• Is a heteropolysaccharide
• An animal storage form of glucose
• 1 and 3
• 2 and 3

60
Starch Glucose homopolysaccharide

• 2 chief constituents amylose and amylopectin
• Amylose 15-20 of most starch
• molecular wt of up to 500,000(glucose mw180 up
  to 2700 glucose units)
• non-branching helical structure
• Amylopectin 80-85 of most starch
• 1,4 and 1,6 glycosidic bonds branches every 5 to
  8 glucose residues
• mw 500,000 to 500,000,000 (over 2700 glucoses)

61
Digestion of Starch Enzymes needed

• Amylose
• Alpha amylase (endoglucosidase)
• clips 1,4 bonds on interior of molecule
• Beta amylase (exoglucosidase)
• clips 1,4 bonds at end of molecule at
  non-reducing end releases Maltoses
• End result maltoses and some maltotrioses
• Maltase breaks down these molecules to glucose
  which is absorbed

62
Starch Digestion Enzymes needed

• Amylopectin
• alpha and beta amylase needed to break 1,4 bonds
  to produce maltose and maltotriose
• maltase to break these down
• then alpha 1,6 glucosidase to breakdown the 1,6
  bonds

63
Summary of Enzymes needed

• 1,4 endoglucosidase (alpha amylase)
• 1,4 exoglucosidase (beta amylase)
• 1,6 glucosidase
• maltase

64
Starch

• Is a heteropolysaccharide
• Is made of amylose
• Is made of amylopectin
• 1 and 2
• 2 and 3

65
Glycogen only homopolysaccharide of animal tissue

• similar to amylopectin in structure but glycogen
  is more highly branched
• branched every 3 to 4 glucose units
• 6,000 to 30,000 glucose units in a glycogen
  molecule
• muscle glycogen shorter than liver
• size dependent on metabolic state of animal
  glucoses constantly added and removed

66
Glycogen

• glycogen used during activity
• slaughtered animal muscle glycogen quickly
  degraded so not much left by the time it is eaten

67
Why is glycogen highly branched?

• So energy is quickly available in emergencies.
• fight or flight reaction
• saber toothed tiger
• epinephrine secreted from adrenal glands
• causes a cascade of reactions to release maltoses
  and then glucoses from the end of the chains
• Glucose acts as a source of energy

68
Amylopectin is more highly branched than glycogen.

• True
• False

69
Glycogen storage

• We have about a 12 to 24 hour supply of glycogen.
  Why dont we store more?
• It takes up quite a bit of space because it is
  highly branched, it isnt very dense
• Fat is more dense so is used for long term
  storage molecule. We have almost unlimited
  ability to store fat.

70
Fiber

• Structural Polysaccharides
• cellulose
• hemicellulose
• pectins
• Structural non-polysaccharides
• lignins
• non-structural polysaccharides
• gums, mucilages algal and seaweed derivatives

71
Lignin is a non-CHO component of fiber and cell
walls
72
Cellulose

• Chief component of plant cell wall framework
• not soluble in ordinary solvents
• long straight chains of beta D glucopyranoside
  units with beta 1,4 bonds
• not digested by digestive enzymes
• MW up to 3000 glucose units
• Most abundant organic compound

73
Hemicellulose Branched heteropolysaccharide

• Hexoses and pentoses
• MW smaller than cellulose
• found as part of cell wall

74
Cellulose and Hemicellulose are found in

• Animal cell membranes
• Plant cell walls
• Animal endoplasmic reticulum
• Animal nuclei
• All of the above

75
Pectic Substances

• Found in fresh fruits, used to solidify jelly
• beta 1,4 D galacturonic acid polymers

76
Fiber intake

• WHO 27-40 grams/day
• 10 g in 41 cups of corn flakes
• 18 grams in one cup of baked beans
• 13 grams in 1 cup of canned peas
• 4 grams in 1 apple with the skin

77
Not all fibers are created equal

• Insoluble Fiber
• cellulose, hemicellulose
• Adds Bulk to the diet laxative
• Decreases risk of cancer by dilution of
  carcinogens
• Limits absorption of minerals
• Soluble Fiber
• Pectic substances oatbran, fruit
• Used as cement to hold cells together
• reduces serum cholesterol

78
Summary of Fiber Effects

• Increases GI tract motility
• Increases volatile fatty acid production which
  increases motility
• softens stools by absorbing water
• Decrease intraluminal pressure less
  diverticulosis
• Decrease glycemic effect and insulin response
• Decrease risk of cancer and high serum cholesterol

79
Dietary Fiber Classification and Definition

• Defn plant components in diet that are resistant
  to digestion in human digestive tract
• Measurement is difficult because it is difficult
  to remove from food because difficult to simulate
  the GI tract

80
Soluble fibers

• Help reduce serum cholesterol
• Are found primarily in animal cell walls
• Are found in oatbran and fruits
• 1 and 3
• All of the above