Proteins ("pro-teens") are found in all living things. One of the easiest types of protein to see is the white of a chicken's egg. When it is uncooked, the protein looks like jelly, but when it is heated up (above 56oC) the protein turns harder and changes from clear to a white colour. This change is called denaturation ("dee-nat-u-ray-shun"), and it can happen to all proteins.


To get an idea of what a protein is, try thinking of a chain - like a bicycle chain. Each link in the bicycle chain is like the links that make up a protein. These links are stuck together, and the chain is described as a protein. Each link of the protein is called an amino ("a-mean-o") acid. In all plants and animals, proteins are made out of a mixture of the 20 main amino acids (see the table below). The things that make one protein different from another are:

  • The type of amino acids they are made up of,
  • The order of the amino acids,
  • The length of the chain is different
Amino acids are the building blocks of proteins. They are organic molecules - which means that they are made out of carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and sometimes sulphur (S) atoms. Each amino acid has a mixture of these atoms which makes it different from any other amino acid.

The 20 Main Amino Acids



Name
1-Letter Nickname
Codons
3-Letter Nickname
Glycine
G
GGT,GGC,GGA,GGG
Gly
Alanine
A
GCT,GCC,GCA,GCG
Ala
Valine
V
GTT,GTC,GTA,GTG
Val
Leucine
L
TTG,TTA,CTT,CTC,CTA,CTG
Leu
Isoleucine
I
ATT,ATC,ATA
Ileu
Serine
S
TCT,TCC,TCA,TCG,AGT,AGC
Ser
Threonine
T
ACT,ACC,ACA,ACG
Thr
Cysteine
C
TGT,TGC
Cys
Methionine
M
ATG
Met
Glutamic Acid
E
GAA,GAG
Glu
Aspartic Acid
D
GAT,GAC,AAT,AAC
Asp
Lysine
K
AAA,AAG
Lys
Arginine
R
CGT,CGC,CGA,CGG,AGA,AGG
Arg
Asparagine
N
AAT,AAC
Asn
Glutamine
Q
GAA,GAG
Gln
Phenylalanine
F
TTT,TTC
Phe
Tyrosine
Y
TAT, TAC
Tyr
Tryptophan
W
TGG
Trp
Proline
P
CCT,CCC,CCA,CCG
Pro


Some other places you can find proteins are:

  • Finger and toe-nails
  • Hair
  • Muscles
  • Hormones
Parents Please Note: The phonetic representations are meant as a guide to pronunciation only. Sound out each group of letters slowly, then faster and faster until they become a word.

Molecule (mol-e-q-ool)
The smallest piece of a substance that still has its chemical properties. The simplest molecules have only one atom, but most molecules have more than one atom which are stuck together.

Atom (at-om)
The smallest piece of a chemical which can not be broken down any further using chemical methods.