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Draw and label the structure of an amino acid.
Objectives
Outline the structures of proteins.
Outcomes
3: Represent the 4 structures of proteins.
5: Explain the structures of proteins.
7: Analyse the importance of the structures of proteins in
biology.
Key terms: protein, primary, secondary, tertiary, quaternary.
How does a protein structure affect its shape?
How does a protein structure affect its shape?
Outcomes
3: Represent the 4
structures of proteins.
5: Explain the structures of
proteins.
7: Analyse the importance of the structures of proteins in
biology.
Key terms: hydrolysis, amino acid, peptide linkage, primary, secondary, tertiary, quaternary
Task
Based on your knowledge of how other biological
molecules have undergone condensation reactions draw
two amino acids bonded together.
Outcomes
3: Represent the 4 structures of proteins.
5: Explain the structures of proteins.
7: Analyse the importance of the structures of proteins in
biology.
Key terms: protein, primary, secondary, tertiary, quaternary.
How does a protein structure affect its shape?
How does a protein structure affect its shape?
Key terms: hydrolysis, amino acid, peptide linkage, primary, secondary, tertiary, quaternary
Outcomes
3: Represent the 4
structures of proteins.
5: Explain the structures of
proteins.
7: Analyse the importance of the structures of proteins in
biology.
Protein StructureTask
Setting up protein chromatography
Outcomes
3: Represent the 4 structures of proteins.
5: Explain the structures of proteins.
7: Analyse the importance of the structures of proteins in
biology.
Key terms: protein, primary, secondary, tertiary, quaternary.
Task
Use the resources available to build up a sheet with
models of different protein structures.
Include types of bond, interactions and examples of
each type.
Outcomes
3: Represent the 4 structures of proteins.
5: Explain the structures of proteins.
7: Analyse the importance of the structures of proteins in
biology.
Key terms: protein, primary, secondary, tertiary, quaternary.
How does a protein structure affect its shape?
Primary structure:
Long line ofamino acids
The 4 structures of proteins
Secondary structure• Form weak bondsand twists to form a 3D structure – alpha helix
Secondary structure
Secondary structure• The amino acids in the primary structure can bond together to
form :
• a) An alpha helix b) a beta pleat
• The bonds involved are hydrogen bonds• Large proteins will have regions containing both structures
Tertiary structure
Tertiary structure• Disulfide bond – fairly
strong.• Ionic bonds – weaker than
above and formed between carboxyl and amino groups.
• Hydrogen bonds – numerous – easily broken
Quaternary structure• Number of
polypeptide chains in tertiary structure.
• Non protein groups too – like haem (prosthetic groups)
Protein StructureTask
Model the structures of proteins. Give examples and explain the bonds present in
each type of structure.
Outcomes
3: Represent the 4 structures of proteins.
5: Explain the structures of proteins.
7: Analyse the importance of the structures of proteins in
biology.
Key terms: protein, primary, secondary, tertiary, quaternary.
Protein structure
Bonds in proteinsThe 3D shape of a protein is maintained by several types of bond, including:
hydrogen bonds:involved in all levels of structure.
hydrophobic interactions:between non-polar sections of the protein.
disulfide bonds: one of the strongest and most important type of bond in proteins. Occur between two cysteine amino acids.
Types of protein
There are two different types of protein and they are different shapes. The shape of a protein molecule is related to its function.
• Globular proteins – these are round, compact and easily soluble so they can be transported in fluids. Examples are haemoglobin and enzymes.
• Fibrous proteins – these are tough and rope-shaped. They tend to be found in connective tissues such as tendons. Collagen is an example of a fibrous protein.
Fibrous proteinsFibrous proteins are formed from parallel polypeptide chains held together by cross-links. These form long, rope-like fibres, with high tensile strength and are generally insoluble in water.
collagen – the main component of connective tissue such as ligaments, tendons, cartilage.
keratin – the main component of hard structures such as hair, nails, claws and hooves.
silk – forms spiders’ webs and silkworms’ cocoons.
Globular proteinsGlobular proteins usually have a spherical shape caused by tightly folded polypeptide chains.
The chains are usually folded so that hydrophobic groups are on the inside, while the hydrophilic groups are on the outside. This makes many globular proteins soluble in water.
enzymes – such as lipase and DNA polymerase.
hormones – such as oestrogen and insulin.
transport proteins – such as haemoglobin, myoglobin and those embedded in membranes.
Protein bondsThe four structural levels in proteins are held together by
different bonds:• Peptide bonds (primary)• Hydrogen bonds (secondary and tertiary)• Ionic bonds (tertiary)• Disulphide bonds (tertiary)• Hydrophobic and hydrophilic interactions (tertiary)Quaternary structure depends on the tertiary structure
of the individual polypeptides, and so is influenced by all these bond types.
Protein StructureWrite about the following, in the context of tertiary structure:
a) Hydrogen bondsb) Ionic bondsc) Van der Waalsd) Disulphide bridgese) Hydrophilic and
hydrophobic regions
Outcomes
3: Represent the 4 structures of proteins.
5: Explain the structures of proteins.
7: Analyse the importance of the structures of proteins in
biology.
Key terms: protein, primary, secondary, tertiary, quaternary.
Protein StructureTask
Retrieve chromatography results.
Outcomes
3: Represent the 4 structures of proteins.
5: Explain the structures of proteins.
7: Analyse the importance of the structures of proteins in
biology.
Key terms: protein, primary, secondary, tertiary, quaternary.
Protein Structure‘Outline the production of a dipeptide by a condensation
reaction. Include the structure of a generalized dipeptide in your
answer.’(Total 5 marks)
Outcomes
3: Represent the 4 structures of proteins.
5: Explain the structures of proteins.
7: Analyse the importance of the structures of proteins in
biology.
Key terms: protein, primary, secondary, tertiary, quaternary.
How does a protein structure affect its shape?
Key terms: hydrolysis, amino acid, peptide linkage, primary, secondary, tertiary, quaternary
Outcomes
3: Represent the 4
structures of proteins.
5: Explain the structures of
proteins.
7: Analyse the importance of the structures of proteins in
biology.
