WALT: To understand the composition and
various structures of proteins.
Sunday, 28 September 2014
~ Identify the basic structures of proteins.
~ Describe how proteins are formed from
~ Describe the differences between the
primary, secondary, tertiary and quaternary
structures of proteins.
What? The weak hydrogen
bonds between the DNA
strands are broken and the
One DNA strand is used as a
Complementary bases pair up
to the template, forming
messenger RNA (mRNA).
mRNA does not have the
base thymine (T). Adenine (A)
pairs with uracil (U) instead.
Where? Inside the nucleus.
Translation Where? In the cytoplasm.
tRNA Protein (polypeptide)
The mRNA is decoded in
groups of 3 (triplet or
Polymer: Protein or polypeptide
Monomer: Amino acid
All Amino Acids have an alkaline amino group (-NH2) and an acid
carboxyl group (-COOH).
There are just 20 naturally occurring Amino Acids, each with a
different -R group.
Primary structure Secondary structure
Tertiary structure Quaternary
Task 1: Fold A3 paper into four and
assign a title for each. Cut out and
stick the relevant statements and
diagrams for each structure in the
Task 2: Add further detail to each
box by answering the questions.
1. Explain how amino acids are joined together to form the primary
2. Explain how one single change in the amino acid chain can affect the
protein from carrying out it’s function.
3. Explain how the weak hydrogen bonds are formed in the secondary
structure of proteins.
4. Name and describe the different bonds that can form in the formation of a
5. Explain how the 3D shape of a protein is important to its function.
6. Explain what a prosthetic group is and name an example.
Further twisting and
folding of secondary
Unique 3d structure.
Weak hydrogen bonds
form between the
Beta pleated sheet
The sequence of
amino acids in the
Test for proteins
The Biuret test.
1.Place a sample in solution in a test tube.
2.Add an equal volume of sodium hydroxide.
3.Add a few drops of dilute copper sulphate
solution and gently mix.
4.Positive purple or negative blue.