Summary 2.1.3 Proteins and enzymes

2.1.3 Proteins and enzymes


Proteins
Amino
 Monomers are amino acids (aa)
acids o Polymer made up of monomers = protein
 Important in growth and repair

Proteins are polymers made from repeating subunits of amino acids. There
are 20 naturally occurring amino acids.


Protein functions
 Hormones
 Enzymes
 Signalling molecules
 Antibodies
 Fluid balance - reduce spikes in pH
 Structural roles
 Transport


Structure of proteins
Primary structure - order of amino acids in a chain
Secondary structure - how polypeptides are coiled. Joined by hydrogen
bonds.
Tertiary structure - 3D “global” shape of the entire protein molecule.
Quaternary structure - proteins with two or more polypeptide chains

Alpha helix and beta pleated sheets are the main two types of secondary
structure. Held together by hydrogen bonds

Protein structure basics
 Built by ribosomes and modified in Golgi and ER
 Most genes code for proteins
 Four levels of protein structure
 May be folded into a range of shapes
 Long fibres, short chains, globular shapes



Feature Bonds Diagram
s

,Primar Sequen Peptide
y ce of bonds
amino
acids in
a
polypept
ide
chain


Second Folded Hydroge
ary structur n bonds
es - -
alpha causes
helix amino
and acids to
beta fold into
pleated repeatin
sheets g
pattern

, Tertiary Overall -
3D Hydroge
structur n bonds
e. Due -Ionic
to bonds
interacti -
ons Hydroph
betwee obic
nR interacti
groups ons
of -
amino Disulfid
acids e bonds
that
make
up the
protein.