Protein structure and function
How do we build a functioning protein from amino acids?
Overview
Learning Objectives:
By the end of this session you should be able to:
- Draw the basic structure of an animo acid
- Define what constitutes each level of protein structure hierarchy (primary, secondary, tertiary, and quaternary)
- (Depending on your prior knowledge) Give (at least three) examples of roles proteins play
Bonus Learning Objectives:
- Bonus Easy: Agree that proteins do many varied and important things for cells and therefore you!
The Structure of Proteins
Amino Acids
Proteins are comprised of amino acids.
What are the key components of amino acids? (i.e. what do I need to be able to draw?)
- Variable Size Chain ( also sometimes referred to as the R group)
- Amino group
- Carboxylic Acid Group
- Central Carbon and Hydrogen
From amino acids to protein: the Hierarchy of Protein Structure
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Primary:
The linear order/sequence of amino acids formed by covalent peptide bonds between adjacent amino acids.
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Secondary:
VCAA 2013: “the coiled or pleated structure within the chain (including α-helices and β-pleated sheets)”- caused by hydrogen-bonding between -C=O and -N-H groups (peptide linkages) within the amino acid chain
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Tertiary:
VCAA 2013: “Tertiary structure: A 3D structure composed of secondary structures”- formed through the interactions of various ‘R’ groups within the molecule
As the function of a protein is determined by its structure, the tertiary structure of a protein is essential to its functioning. If the protein is reshaped in any way, the protein may no longer be able to do its job.
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Quaternary:
VCAA 2013: “Quaternary structure: Two or more polypeptide chains joined together”
The varied roles of proteins
(i.e. the proteome)
What is the proteome?
The entire set of proteins expressed by an organism (for more information, see the definition on scitable).
What are some of the proteins which make up the proteome?
- Enzymes
- Membrane transport
- Antibodies
- Complement proteins
Can you list any more kinds of proteins? What are their roles?
Don’t worry if you can’t yet answer these questions easily; you undoubtedly will once you’ve progressed further in the course and have learnt more about the above proteins.
Just make a note to come back when you do, and check that you can now answer the questions!
Today’s TL;DR
- Proteins are 3D dimensional folded structures (called ‘polymers’) comprised of smaller repeating subunits (amino acids)
- Amino acids are comprised of a central carbon, a variable group, a carboxylic acid group and a amine group