Transcript Amino Acids - Clydebank High School

Amino Acids - The Building
Blocks of Life!
 Amino
acids are molecules containing both the amide
group – NH2 at one end of the molecule and carboxyl
group COOH at the other end of the molecule.
 H2N – Δ – COOH
 The Δ part of the molecule represents various
arrangements of atoms.
 There are just over 20 different types of Amino Acids.
 They join together in condensation reactions to form
proteins.
Joining Amino Acids
H
O
I
II
N–R–C
I
I
H
OH
H
O
I
II
+ N–R*-C
I
I
H
OH
The products
H
O H
O
I
II I
II
N–R–C–N–R*-C
+ H2O
I
I
H
OH
They are held together by a peptide link CONH
(amide link)
Proteins
Proteins are
made when thousands of amino
acids join by condensation polymerisation.
Very many
different types of proteins can be
made. ( compare number of possible words with
26 letters. > 20 Amino acids = many different
proteins)
Types of Proteins
 There
are 2 main types – Fibrous and Globular
 Fibrous Proteins
 Long, thin linear molecules.
 Hydrogen bonding exists between the COOH and NH2
groups in near by chains or within the same chain.
 Examples – Keratin ( hair, wool, nails)
Elastins ( lungs and arteries)
Collagens ( skin and tissue)
Globular Proteins
They
contain intermolecular bonding which can
cause the molecule to become a spiral chain.
They are involved in human biological processes.
 Examples – Enzymes, hormones and
haemoglobin.
Enzymes
 Enzymes
are biological catalyst.
 They speed up the rate of reactions in living organisms.
 Enzymes are PROTEINS.
 They are very specific.
 They usually only catalyse 1 type of reaction.
 When enzymes are at the wrong temperature or pH –
they are denatured ( destroyed).
 They work at optimum conditions – pH and T.
Lock and Key
 Enzymes
are so specific because of the “lock and key”
model.
 The enzyme molecule will only let reactant
(substrate) molecule which have the correct shape and
orientation.
 They form an intermediate complex.
 The new substance forms and then leaves the enzyme
surface – which can then be reused.
 When an enzyme is denatured the shape of the protein
molecules, of the enzyme, has changed and the
reactants no longer fit.
Hydrolysis of Proteins
 This
is the type of reaction where large protein
molecules are broken down back into amino acids.
Water is added.
 This is what happens to proteins when they are digested.
 This enables the smaller molecules to pass into the
blood stream.
 Some amino acids can not be stored/made in the body,
we have to take them, in our diet, on a regular basis –
these are essential amino acids.
 They are essential for protein synthesis.