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AS OCR BIOLOGY F212…read more

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The Basics
· The general formula for a sugar unit is C(n)H2
· Carbohydrates are sugars, starches and
· Sugars and starches are always soluble in
water and taste sweet.
· Cellulose is insoluble and doesn't taste sweet.…read more

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· A monosaccharide is a molecule that contains
just one sugar unit. E.g. Glucose, Fructose and
· The only difference
between alpha and beta
is the H and OH on the
End is swapped around.
In alpha the H is on the top.…read more

Slide 4

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· Two monosaccharide molecules are linked together.
· This is a condensation reaction.
· The links formed are called glycosidic bonds which involve covalent bonds and are
very strong.
· They are soluble in water and taste sweet.
· 2 Glucose = Maltose
· In maltose glycosidic bond is formed between the carbon atom 1 and 4 of the
other, so is described at a 1-4 glycosidic bond and links together by the O.
· When digested, Glycosidic bonds are broken
down by carbohydrate enzymes. This is a
Hydrolysis reaction.…read more

Slide 5

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· Links thousands of alpha molecules with 1-4 glycosidic bonds.
· Produce Amalose which is found in starch and is how plants store carbohydrates
made in photosynthesis.
· Molecules coil around to form a long spiral making them very compact so a lot of
starch can be store in small space and are held in shape by hydrogen bonds.
· Cellulose is also a polysaccharide but is made from Beta glucose with 1-4 glycosidic
bonds. They don't coil like Amalose does but lies flat and forms hydrogen bonds
with there partner.
· Produces bundles of molecules lying side by side called fibrils and form larger
bundles called fibres which are structurally very strong, difficult to digest and very
few animals have an enzyme that can break its glycosidic bonds.…read more

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Plants contain Amylose and cellulose, animal cells never contain either,
instead they store carbohydrates as glycogen. Stores are found in the liver
and in muscles. They are easily broken down by glycogen phosphorlyse to
form glucose, activated by insulin when blood glucose is low.
· They are structured similarly to amylose however has branches where 1-6
bonds are formed making it more difficult for glycogen molecules to form
helices.…read more


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