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Molecules: Part
2 - Proteins…read more

Slide 2

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Proteins in Living Organisms
Proteins make up about 50% of organic matter in
cells and are made up of carbon, hydrogen,
oxygen, nitrogen and sometimes sulphur.
They are used for:
· Structural components ­ muscle and bone
· Membrane carriers and pores ­
· Enzymes
· Many Hormones
· Antibodies
They are important for growth and repair and
metabolic activity in all organisms…read more

Slide 3

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Amino Acids
· Amino acids are the monomers
that make up proteins.
· They all have the same basic
structure ­ they have an amino
group at one end and an acid
group at the other.
· They join end to end to give a
repeating `backbone' of N-C-C-
· However not all amino acids are
identical ­ There are 20 types
that are naturally occurring.
· This is because they have
different R-groups ­ These
range from a simple H to a
complicated group which is
larger that the C-C-N part of the
R-Group · Some R-Groups are positively
charged, some are negatively,
Amino group Acid Group some are Hydrophilic and some
Hydrophobic.…read more

Slide 4

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Amino Acids in Plants and Animals
· Plants are able to manufacture amino acids as long as they can take
nitrates up from the soil. This nitrate is converted to the amino
groups and bonded to the organic groups which are made from the
products of photosynthesis.
· Animals have to obtain amino acids from the proteins that they eat.
· 8-10 of the 20 amino acids cannot be built from the materials that
animals take into their bodies.
· These amino acids are `essential amino acids' as they need to be
part of the diet.
· Most are found in meat so vegetarians need to be careful to balance
their diet to get all the essential amino acids
· In animals, amino acids cannot be stored because the amino group
makes them toxic.
· Therefore the amino group is removed in the liver by a process
called Deamination and converted to urea and removed in the
urine.…read more

Slide 5

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Joining Amino Acids
· All amino acids join the
same way no matter
which R-group they have.
· There is a condensation
reaction between the acid
group of one amino acid
and the amino group of
the other amino acid.
· This forms a covalent
bond called a Peptide
· The new molecule formed
is called a Dipeptide.
· Breaking the peptide
bond is also called
Hydrolysis and it uses the
water to break the bond.…read more

Slide 6

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The Primary Structure
· An organism may
contain 10000 or
more different
proteins, each with a
different function.
· The function of a
protein is
determined by its
structure and this
structure is
determined by its Definition: The primary
sequence of amino structure is given by the
acids. specific sequence of amino
· This unique acids that make up the
sequence is its
primary structure. protein.…read more

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