A level Biology AQA Biological molecules

Proteins
•
Proteins
of
long
are a diverse

chains

Structural
of amino




Skin
:




,
group of




ligaments
acids .
large and




and hair .
ntofboay+issuesi" "m"
complex polymer molecules ,
made up




Catalytic :



All enzymes are proteins catalysing many biochemical reactions
,




signalling
Many hormones and receptors are protein
Immunological
All antibodies are proteins .




AMINO ACIDS

All amino acids have the same
'


general structure : the only difference between each one

is the nature of the R R
group .
The R group The .
group therefore defines an amino acid .




'
Amino acids are the monomers from which proteins are made .




-
Mino group carboxyl group

H O H
H
l l " l
C C
N
'
H2H C CO0H
/ I I
H OH
R R

R ( side ) group




PIPTIDE 3011 ]

The peptide bond
•

forms between the carboxyl group on one amino acid and the amino

amino group on the other amino acid

This produces water
-


,
so the reaction is a condensation reaction

The di peptide be split back into two amino acids in hydrolysis reaction
-
can a .




H O H
H o
I 11 I "
\
N C C N C C
'
/ I I
H 1 OH
R H R

peptide bond




•

When more amino acids are added to a di peptide a
polypeptide chain is formed
'
A protein consist chains folded into
of one or more
polypeptide a
highly specific 3D

shape
'

There are up to four levels of structure in a protein :
primary secondary , tertiary
, .