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OCR AS Biology
Jessica Birbeck…read more

Slide 2

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Introduction To Carbohydrates
The 3 main functions of carbohydrates are:
- Release of energy during respiration e.g.
- Store of potential energy e.g. starch
- Structure (in some organisms) e.g. cellulose
Carbohydrates contain the elements carbon,
hydrogen and oxygen. Carbohydrates are
found in the proportions of Cn(H2O)n.
Therefore, for every carbon atom there is
the same amount of water molecules.
For example, the formula for glucose is
C6H12O6. There is 6 carbon atoms and also 6
water molecules.…read more

Slide 3

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Simple Sugars
- The simplest carbohydrates are called monosaccharides. These are the
monomers of carbohydrates. These monomers are like the 'building
blocks' of larger carbohydrates which are called polysaccharides e.g.
They all have 3 similar properties. They:
-Are soluble in water
- Are sweet tasting
-Form crystals
The number of carbon atoms in the molecule determines which group the
sugars belong to.
3-carbon monosaccharides are known as triose sugars. These molecules each
contain 3 carbon atoms.
5-carbon monosaccharides are known as pentose sugars.
6-carbon monosaccharides are known as hexose sugars.…read more

Slide 4

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Two Types of Glucose
As shown in the diagram on the left,
there is an OH at C1 and this is below
the plane of the ring.
Beta glucose is slightly different, there is an
OH bond with C1 but it is found above the
plane of the ring.
Alpha and Beta glucose are made up of the
same elements and with the same
quantities. However, they are structurally
different and are therefore isomers of each
other.…read more

Slide 5

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Two monosaccharide molecules can be joined together in a condensation reaction.
Here, a water molecule is removed at a bond is formed between C1 of one
monosaccharide and C4 of another. This bond is a covalent bond called a glycosidic
In reverse, a disaccharide molecule can be split by a hydrolysis reaction. In this
reaction a water molecule is added and the glycosidic bond is broken.…read more

Slide 6

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Energy Release
Most cell processes require energy in the form of ATP. When the bonds in
glucose are broken during respiration to form simpler molecules of carbon
dioxide a water, energy is released. This energy is then used to produce ATP.
The word equation for respiration is:
Glucose + Oxygen ---------> Carbon Dioxide + Water + Energy
The breaking down of glucose is made of many different steps and each step is
driven by a specific enzyme. In order for the glucose to be respired, the
organism must have a specific enzyme.
Plants and animals contain enzymes which can only break down a-glucose. Thi
is because the function of an enzyme is based on it's shape. A-glucose and B-
glucose have slightly different structures which are mentioned on the
previous slide. This means that a-glucose can be respired by plants and
animals whereas B-glucose cannot.…read more

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Miss Meera J


A good presentation, however it was not thoroughly detailed as much I hoped it would be, but overall good.  

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