Proteins Flashcards
Define the various classes of amino acids.
Aliphatic
Aromatic
Sulphur containing
Acidic
Basic
Polar
‘Miscellaneous’
Define ‘primary structure’.
Primary structure of a protein is the polypeptide chain structure.
Define ‘secondary structure’.
Secondary structure refers to the 3D spatial arrangement of the polypeptides.
Secondary structure relies on H bonding.
Examples would be;
alpha helices, beta-pleated sheets.
Define ‘tertiary structure’.
Tertiary structure refers to the interactions between the R groups of different proteins.
Van der Waals forces, ionic, hydrogen, disulphide bridges, hydrophobic interactions.
The tertiary structure is required to confer the function of a protein.
Define ‘quaternary structure’.
Quaternary structure does not apply to EVERY protein as the other structures do.
Quaternary structure refers to more than one polypeptide chain with their own tertiary structure.
Creates a complex.
Describe what happens to a protein when it is denatured.
The bonds of the protein would be disrupted or destroyed.
The protein would lose its biological function.
Despite losing its function, the protein retains its identity.
Describe the functions of proteins.
Proteins can be:
Structural
Enzymatic
Contractile
Receptor
Hormonal
Transport
Storage
Defensive
Name the three different kinds of conjugated proteins.
Glycoproteins
Lipoproteins
Metalloproteins
Define a glycoprotein.
Glycoproteins are proteins with one or more carbohydrate molecule (s) attached.
Define a lipoprotein
Lipoproteins are found in cell membranes.
They are responsible for transporting hydrophobic molecules.
Examples; fats; fat soluble vitamins; fat soluble hormones.
They form complexes with other lipoproteins.
Define metalloproteins.
Metalloproteins are proteins with 1 or more metal ions within their structures (co-factors).
Describe the properties that come from the possession of quaternary structure.
An example;
HAEMOGLOBIN
Haemoglobin is composed of 2 alpha helices and 2 beta-pleated sheets.
Each subunit has one haeme group attached, (with an Iron molecule).
This allows haemoglobin to transport 4 O2 molecules.
Compare the structures and functions of fibrous and globular proteins.
Globular proteins are spherically shaped and are used as; storage; enzyme; hormones; transport; structure.
Fibrous proteins have an elongated structure, which correlates with their function. They function as muscle fibres and connective tissue.
