Transcript Review Question 1 - mr-youssef-mci

Review Question 1
• How many molecules of water are needed to
completely hydrolyze a polymer that is 4
monomers long?
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Review Question 2
• After you eat a slice of apple, which reactions
must occur for the amino acid monomers in
the protein of the apple to be converted into
proteins in your body?
Amino acids are incorporated into proteins in
your body by dehydration reactions
CARBOHYDRATES
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Carbohydrates
• Serve as fuel and building
material
• Include both sugars and their
polymers (starch, cellulose, etc.)
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Sugars
• Monosaccharides
– Are the simplest sugars
– Contain a single chain of carbon atoms
with hydroxyl groups
– They also contain carbonyl (aldehyde
or keytone) groups
– Can be combined into polymers
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• Examples of monosaccharides
Triose sugars
(C3H6O3)
H
O
Aldoses
C
Pentose sugars
(C5H10O5)
H
O
C
H
O
C
O
C
C OH
H C OH
H
C OH
H C OH
H
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H
Ribose
H
Ketoses
H
H
Glyceraldehyde
H
H C OH
H C OH
HO C H
HO C H
HO C H
H
H
Glucose
Galactose
H
H C OH
H C OH
H C OH
C O
C O
C O
H C OH
H C OH
HO C H
H
H C OH
H C OH
Dihydroxyacetone
H C OH
H C OH
H
Ribulose
Figure 5.3
Hexose sugars
(C6H12O6)
H C OH
H
Fructose
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• Monosaccharides
– May be linear
– Can form rings
O
H
1C
H
HO
2
3
C
6CH OH
2
OH
H
C
H
4
H
H
H
C
C
C
H
OH
4C
OH
OH
OH
5C
H
O
H
OH
5
6
5C
6CH OH
2
3
C
H
2C
O
H
H
4C
1C
CH2OH
O
OH
H
OH
3C
6
H
1C
H
2C
4
H
OH
HO
3
OH
H
H
1
OH
2
OH
H
H
O
5
OH
OH
H
Figure 5.4 (a) Linear and ring forms. Chemical equilibrium between the linear and ring
structures greatly favors the formation of rings. To form the glucose ring,
carbon 1 bonds to the oxygen attached to carbon 5.
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α glucose vs. β glucose
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• Oligosaccharides – contain two or three
monosaccarides attached by covalent
bonds called glycosidic linkages
– Disaccharides
• Consist of two monosaccharides
• Are joined by a single glycosidic linkage
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(a)
Dehydration reaction
in the synthesis of
maltose. The bonding
of two glucose units
forms maltose. The
glycosidic link joins
the number 1 carbon
of one glucose to the
number 4 carbon of
the second glucose.
Joining the glucose
monomers in a
different way would
result in a different
disaccharide.
CH2OH
CH2OH
H
O
H
OH
H
OH
HO
H
H
H
HO
O
H
OH
H
H
OH
CH2OH
H
OH
OH
O
H
H
OH
CH2OH
H
1
H
HO
O
H
4
H
OH
H
H
OH
O
H
OH
1–4
glycosidic
linkage
H
OH
OH
H2O
Glucose
Glucose
CH2OH
H
(b) Dehydration reaction
HO
in the synthesis of
sucrose. Sucrose is
a disaccharide formed
from glucose and fructose.
Notice that fructose,
though a hexose like
glucose, forms a
five-sided ring.
O
H
OH
H
H
CH2OH
H
OH
HO
H
CH2OH
O
H
H
O
H
H
OH
HO
CH2OH
OH
OH
Maltose
H
CH2OH
1–2
glycosidic
1
linkage
O
H
H
2
H
HO
O
HO
H
OH
CH2OH
OH
H
H2O
Glucose
Fructose
Sucrose
Figure 5.5
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Polysaccharides
• Polysaccharides
– Are polymers of sugars with several hundred to
several thousand monosaccharide subunits held
together by glycosidic linkages
– Serve many roles in organisms
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Storage Polysaccharides
Chloroplast
Starch
• Starch
– Is a polymer
consisting entirely
of glucose
monomers
– Is the major
storage form of
glucose in plants
1 m
Amylose
Figure 5.6
Amylopectin
(a) Starch: a plant polysaccharide
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Two types of Starch
• Amylose
– Straight chain polymer of α (alpha) glucose
– Has 1-4 glycosidic linkages
• Amylopectin
– Branched chains of α glucose and β glucose
– Has 1-4 glycosidic linkages in the main chains and
1-6 glycosidic linkages at the branch points
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Glucose Storage in Animals
• Glycogen
– Consists of glucose monomers
– Similar to Amylopectin (has 1-4 and 1-6
glycosidic linkages), but there are more
branches in glycogen
– Stored in muscle and liver
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Mitochondria
Giycogen granules
0.5 m
Glycogen
Figure 5.6
(b) Glycogen: an animal polysaccharide
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Structural Polysaccharides
• Cellulose
– Is a polymer of glucose
– Has different glycosidic linkages than starch
– The main structural polysaccharide in plants and plant cell
walls
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– Cellulose is a straight chain polymer of β glucose with
1-4 glycosidic linkages
H
O
C
CH2OH
H
4
H
OH
O
H
H
OH
HO
H
OH
 glucose
H
C
OH
HO
C
H
CH2OH
O
H
OH H
H
4
H
C
OH
H
C
OH
H
C
OH
HO
OH
1
H
H
OH
 glucose
(a)  and  glucose ring structures
CH2OH
CH2OH
O
HO
O
4
1
OH
O
1
OH
O
4
O
1
OH
OH
OH
CH2OH
CH2OH
O
O
4
1
OH
O
OH
OH
(b) Starch: 1– 4 linkage of  glucose monomers
CH2OH
O
HO
Figure 5.7 A–C
OH
OH
O
1
4
OH
OH
CH2OH
O
O
OH
O
O
CH2OH
OH
OH
(c) Cellulose: 1– 4 linkage of  glucose monomers
OH
O
CH2OH
OH
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– Unlike amylose and amylopectin (starches),
cellulose molecules are neither coiled nor
branched
Cellulose microfibrils
in a plant cell wall
Cell walls
Microfibril
About 80 cellulose
molecules associate
to form a microfibril, the
main architectural unit
of the plant cell wall.
0.5 m
Plant cells
OH CH2OH
CH2OH
O O
O O
OH
OH
OH
O
O O
OH
OH CH2OH
Parallel cellulose molecules are
held together by hydrogen
bonds between hydroxyl
groups attached to carbon
atoms 3 and 6.
Figure 5.8
O
CH2OH
O
OH O
OH
CH2OH
O O
O OH
OH
OH
OH
O O
CH2OH
OH
OH
O O
CH2OH
CH2OH
O O
OH
OH
CH2OH
O O
OH
OH
 Glucose
OH
OH
O O
CH2OH
OH
Cellulose
molecules
OH
O O
CH2OH
OH
OH O
O
CH2OH
A cellulose molecule
is an unbranched 
glucose polymer.
monomer
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• Cellulose is difficult to digest
– However, it does contribute to “roughage” in the
diet  fibre
– Cows have microbes in their stomachs to facilitate
this process
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Figure 5.9
• Chitin, another important structural
polysaccharide
– Is found in the exoskeleton of arthropods
– Can be used as surgical thread
– http://www.youtube.com/watch?v=9yTe9ypV0Qo
– http://www.youtube.com/watch?v=fy12sppepRQ&feature=related
CH2OH
O OH
H
H
OH H
OH
H
H
NH
C
O
CH3
(a) The structure of the
chitin monomer.
Figure 5.10 A–C
(b) Chitin forms the exoskeleton
of arthropods. This cicada
is molting, shedding its old
exoskeleton and emerging
in adult form.
(c) Chitin is used to make a
strong and flexible surgical
thread that decomposes after
the wound or incision heals.
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