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Carbohydrates
2.6
2.6
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CarbohydratesCarbohydrates are made from CARBON, HYDROGEN and OXYGEN
Plant cell walls depend on the structural role of some carbohydrates
They STORE ENERGY in plants and animals
MONOSACCHARIDES
CARBOHYDRATES
POLYSACCHARIDESDISACCHARIDES
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(CH2O)n
MonosaccharidesMonosaccharides are small organic molecules used as bulding blocks for more complex carbohydrates. Click each of the blue boxes to work through the slide.
General FormulaWhat does the ‘n’
stand for?
Number of Carbon atoms
So, when n=3TRIOSE, e.g. glyceraldehyde -
In metabolic reactions
When n=5 When n=6
HEXOSE, e.g. glucose -
main source of energy
PENTOSE, e.g. ribose –
formation of nucleic acidnextnext
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sIsomerism in Glucose C6H12O6
CHCH22OHOH
CHCH22OHOH
Alpha-glucose
beta-glucose
Show structural changeShow structural change
Oxygen
Hydrogen
Carbon
Hydroxide (OH)
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GLUCOSE
MALTOSESUCROSE
GLUCOSE
GLUCOSE
Disaccharides
A disaccharide can be made from two of the same
monosaccharide molecule or from two different ones.
Disaccharides form when two monosaccharide units join forming a
glycosidic bond, by a condensation reaction.
The combination of monosaccharides determines which disaccharide is formed.
MONOSACCHARIDES DISACCHARIDE
FRUCTOSEGALACTOSE
WATERWATERWATER
LACTOSE
GLUCOSE
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OOHOH
Forming Disaccharides
C C
C
C O
C
H
OH
OHOH
OH
HH
CH2OH
H
H
CHCH22OHOH
C C
C
C O
C
H
OH
OHOH
OH
HH
CH2OH
H
H
C C
C
C O
C
H
OH
OH
OH
HH
CH2OH
H
H
C C
C
C O
C
H
OH
OH
OH
HH
CH2OH
H
H O
H H
GlycosidicBond This is a
CONDENSATION reaction, where a water molecule is lost.
Glucose
Maltose
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sPolysaccharides
Polysaccharides are large complex molecules known as
POLYMERS.
Monomers are the individual monosaccharides which join to form the polysaccharide.
Polymerisation is the process of bonding many MONOMERS by condensation reactions to form one large molecule.
Po
lys
acc
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s Monomer Glycosidic bond
Cellulose β Glucose 1-4
Amylose Glucose 1-4
Glycogen Glucose 1-4 and 1-6
Return to isomerism of glucoseReturn to isomerism of glucoseNextNext
What is polymerisation
?
What is a monomer?
Click the bubble for the answer
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OOHOH
Forming polysaccharides
C C
C
C O
C
H
OH
OH
HH
CH2OH
H
H
C C
C
C O
C
H
OH
OH
OH
HH
CH2OH
H
H
O
H H
In this example, 3 condensation reactions have produced 3 water molecules to produce the polysaccharide.
O
H H
C C
C
C O
C
H
OH
OH
OH
HH
CH2OH
H
H
C C
C
C O
C
H
OH
OH
HH
CH2OH
H
H
OHOH OHOH
Glucose
O
O
H H
O
A HYDROLYSIS reaction (addition of water) reverses the reaction and splits the polysaccharide releasing 3 monosaccharide molecules.
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sYou can give this question a go, in order to prove your understanding: