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Carbohydrates…read more

Slide 2

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This is -glucose
(C6H12O6), a basic
Monosaccharides have
the general formula
CnH2nOn, where n can be
any number between 3
and 7.
This is -glucose. The
only difference between
-glucose and -glucose
is that the H and OH
groups around the C6
atom are inverted.
Therefore -glucose and
-glucose are isomers.
Other isomers include
fructose and galactose.…read more

Slide 3

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Disaccharides form
when two
Disaccharides monosaccharides
(eg -glucose) join
A molecule of water
(H2O) is removed,
therefore it is called
a condensation
The leftover oxygen
joins onto the carbon
which lost an OH, in
this case forming an
1-4 glycosidic
bond, and the
The reverse of this
reaction is called
hydrolysis, as water
is added.…read more

Slide 4

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Benedict's Test
· A reducing sugar is a sugar that can donate electrons to another
· All monosaccharides and some disaccharides are reducing sugars
· Reducing sugars can be tested for using the Benedict's test
· A solution is dissolved in water, an equal volume of Benedict's
reagent is added, and this solution is gently heated.
· The more colour changes (from blue, to green, to yellow, to orange,
to red) that the solution goes through, the higher the concentration
of reducing sugars.
· This makes the Benedict's test semi-quantitative, as results can be
compared to see what has a higher and lower concentration, but the
actual concentration cannot be found with this method.
· Non-reducing sugars can also be found, by adding hydrochloric acid
before the test to induce hydrolysis, then adding a buffer to control
pH before the Benedict's reagent.…read more

Slide 5

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· Polysaccharides are polymers, formed by many
monosaccharide molecules by condensation.
· Polysaccharides, unlike monosaccharides, are
insoluble, as they are so large.
· Some polysaccharides are used as storage
molecules (starch for plants, glycogen for
animals), whereas others (such as cellulose) are
used to provide structure
· Iodine is used to test for starch, as it turns
blue/black when starch is present.…read more

Slide 6

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Digestion of carbohydrates
Teeth chew food, Salivary amylase
breaking it down and hydrolyses starch to
giving it a larger surface maltose
area Food is swallowed,
Pancreatic amylase amylase is denatured by
passes into the small stomach acid to prevent
intestine with food, further hydrolysis
completing any Epithelial lining in
hydrolysis of starch to small intestine
maltose produces maltase,
Glucose (and sodium which hydrolyses the
ions) absorbed into maltose into -glucose
blood via active
Glucose carried to cells
for respiration.…read more

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