Introduction to
Carbohydrate Unit
1. What is the predominant
monosaccharide in carbohydrates?
•Glucose, also
referred to as
dextrose
#s 2-4
• “Di” = 2; two monosaccharide
units
• Oligo: 3-10 monosaccharide units
• Poly: >10 monosaccharide units
#5 What is a common suffix for [specific]
carbohydrates? List common carbohydrates
•-Ose
•Saccharide: derived from the
Greek sakchar, meaning sugar
or sweetness
#5 Specific examples of carbohydrates
• Monosaccharides
–Examples: glucose
(C6H12O6), fructose, and
galactose, ribose
• Disaccharides
–Examples: sucrose, lactose,
and maltose
#5 Specific examples of Carbohydrates
• Oligosaccharides: 3-10 sugars
–Raffinose and stachyose
• Polysaccharides
–Examples: starch, pectin,
cellulose, and glycogen
• Sugar alcohols
–Sorbitol, xylitol
#6 & #9: What is the name of the reaction by which di-,
oligo-, and polysaccharides are formed? What is the name
of the bonds between carbohydrates monomers?
• Dehydration synthesis/condensation
• (#9 )This type of rxn forms a
glycosidic bond (C-O-C) also called
glycosidic linkage
–Two forms:
alpha and beta
10. How do alpha and beta glycosidic bonds
differ and how can this affect digestion?
• Alpha differs from the beta glycosidic bond only
in the angle of formation between the two sugars
• Alpha-glycosidic linkage is below the plane of
the rings and the beta glycosidic linkages are
above
• Humans lack enzymes needed to cleave betaglycosidic linkages – lactose intolerance
16. Why are oligosaccharides "gassy"?
• Can’t be broken down
in small intestine and
become “food” for
bacteria of large
intestine
• Bacterial metabolism
of oligosaccharides
results in gas
byproducts
7. What is the name of the reaction by which di-,
oligo-, and polysaccharides are broken down?
• Hydrolysis
–The addition of a water molecule
across a bond
–The breaking down of a chemical
compound into two or more simpler
compounds by reacting with water.
• http://nhscience.lonestar.edu/biol/dehydrat/d
ehydrat.html
#8 – Summarize the relationship between
dehydration synthesis and hydrolysis
• They are reverse rxns, where
one is a synthesis rxn and
one is a break down rxn
Hydrolysis  Dehydration Synthesis
Disaccharide + H20  MonoSach + MonoSach
• http://youtu.be/b7TdWLNhMtM
11. In your own words, describe
how/why cyclic carbohydrates form.
12. How are carbohydrates found in
humans classified?
• By number of carbons
–Trisoses
–Pentoses
–Hexoses
–Septoses….
6
5
13. Carbs are also classified by their functional
groups - what are the names of these
classifications?
• Aldoses – contain aldehyde functional group
– Terminal carbonyl C=O
• Ketoses – contain ketone functional group
– Internal carbonyl
Carbonyl carbon
Carbonyl Carbon
• In the closed-ring (cyclic) structure,
the carbonyl carbon is the one which
is attached to the O of the ring and
an OH group
14. Where can your body storage
glucose?
• Liver as glycogen
• Smaller amounts in muscles
and brain as glycogen
• Circulates in blood stream in
very specific range
15. What are indigestible forms of
polysaccharides known as?
• Dietary fiber
17. Explain the basic relationship
between sugar and diabetes.
• Insulin: pancreatic hormone
which signals cells to uptake
glucose from blood (into cells)
• People with Diabetes either do
not produce insulin or do not
respond to insulin that is present
18. How does the glycemic index
classify carbohydrates?
•By how quickly and how high a
specific carbohydrate boosts blood
glucose levels compared to pure
glucose
19. List food sources of carbohydrates
• Grains (breads, rice, pasta,
cereal)
• Fruit
• Dairy
• Beans, legumes
• Soda, candy, etc.
20. List some functions of
carbohydrates:
• Energy source for cells; primary for
brain
• Protein sparing
• Breakdown of fats and preventing
ketosis
• Biological recognition
• *Dietary fiber & digestive health
• *Flavor and sweeteners