review question 1 how many molecules of water are needed to completely hydrolyze a polymer that is...
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Review Question 1
• How many molecules of water are needed to completely hydrolyze a polymer that is 10 monomers long?
9
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
3
4
Carbohydrates
• Serve as fuel and building material
• Include both sugars and their polymers (starch, cellulose, etc.)
5
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
6
• Examples of monosaccharidesTriose sugars
(C3H6O3)Pentose sugars
(C5H10O5)Hexose sugars
(C6H12O6)
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
HO C H
H C OH
H C OH
H C OH
H C OH
HO C H
HO C H
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
C OC O
H C OH
H C OH
H C OH
HO C H
H C OH
C O
H
H
H
H H H
H
H H H H
H
H H
C C C COOOO
Aldo
ses
Glyceraldehyde
RiboseGlucose Galactose
Dihydroxyacetone
Ribulose
Keto
ses
FructoseFigure 5.3
7
• Monosaccharides– May be linear– Can form rings
H
H C OH
HO C H
H C OH
H C OH
H C
O
C
H
1
2
3
4
5
6
H
OH
4C
6CH2OH 6CH2OH
5C
HOH
C
H OH
H
2 C
1C
H
O
H
OH
4C
5C
3 C
H
HOH
OH
H
2C
1 C
OH
H
CH2OH
H
H
OHHO
H
OH
OH
H5
3 2
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.
OH3
O H OO
6
1
Figure 5.4
α glucose vs. β glucose
8
9
• 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
10
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.
Dehydration reaction 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.
(a)
(b)
H
HO
H
HOH H
OH
O H
OH
CH2OH
H
HO
H
HOH H
OH
O H
OH
CH2OH
H
O
H
HOH H
OH
O H
OH
CH2OH
H
H2O
H2O
H
H
O
H
HOH
OH
OH
CH2OH
CH2OH HO
OHH
CH2OH
HOH H
H
HO
OHH
CH2OH
HOH H
O
O H
OHH
CH2OH
HOH H
O
HOH
CH2OH
H HO
O
CH2OH
H
H
OH
O
O
1 2
1 41– 4
glycosidiclinkage
1–2glycosidic
linkage
Glucose
Glucose Glucose
Fructose
Maltose
Sucrose
OH
H
H
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
12
Storage Polysaccharides
• Starch– Is a polymer
consisting entirely of glucose monomers
– Is the major storage form of glucose in plants
Chloroplast Starch
Amylose Amylopectin
1 m
(a) Starch: a plant polysaccharideFigure 5.6
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
15
16
MitochondriaGiycogen granules
0.5 m
(b) Glycogen: an animal polysaccharide
Glycogen
Figure 5.6
17
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
(c) Cellulose: 1– 4 linkage of glucose monomers
H O
O
CH2OH
HOH H
H
OH
OHH
H
HO
4
C
C
C
C
C
C
H
H
H
HO
OH
H
OH
OH
OH
H
O
CH2OH
HH
H
OH
OHH
H
HO4 OH
CH2OHO
OH
OH
HO41
O
CH2OH
O
OH
OH
O
CH2OH
O
OH
OH
CH2OH
O
OH
OH
O O
CH2OHO
OH
OH
HO 4O
1
OH
O
OH OHO
CH2OHO
OH
O OH
O
OH
OH
(a) and glucose ring structures
(b) Starch: 1– 4 linkage of glucose monomers
1
glucose glucose
CH2OH CH2OH
1 4 41 1
Figure 5.7 A–C
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Plant cells
0.5 m
Cell walls
Cellulose microfibrils in a plant cell wall
Microfibril
CH2OH
CH2OH
OH
OHO
OOHO
CH2OHO
OOH
OCH2OH OH
OH OHO
O
CH2OH
OO
OH
CH2OH
OO
OHO
O
CH2OHOH
CH2OHOHOOH OH OH OH
O
OH OH
CH2OH
CH2OH
OHO
OH CH2OH
OO
OH CH2OH
OH
Glucose monomer
O
O
O
O
O
O
Parallel cellulose molecules areheld together by hydrogenbonds between hydroxyl
groups attached to carbonatoms 3 and 6.
About 80 cellulosemolecules associate
to form a microfibril, themain architectural unitof the plant cell wall.
A cellulose moleculeis an unbranched glucose polymer.
OH
OH
O
OOH
Cellulosemolecules
Figure 5.8
– Unlike amylose and amylopectin (starches), cellulose molecules are neither coiled nor branched
20
• 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
Figure 5.9
21
• Chitin, another important structural polysaccharide– Is found in the exoskeleton of arthropods– Can be used as surgical thread
(a) The structure of the chitin monomer.
OCH2OH
OHHH OH
H
NH
CCH3
O
H
H
(b) Chitin forms the exoskeleton of arthropods. This cicada is molting, shedding its old exoskeleton and emergingin adult form.
(c) Chitin is used to make a strong and flexible surgical
thread that decomposes after the wound or incision heals.
OH
Figure 5.10 A–C
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