Proteins Flashcards
Describe the structure of an amino acid (with the aid of a diagram).
They consist of an amine group, a carbon chain, a carboxylic group, an H side chain and an R side chain.
Describe the synthesis of a peptide bond.
A covalent peptide bond forms between the N of the amine group of one amino acid and the C from the carboxyl group of another. This is a condensation reaction.
Describe the hydrolysis of a peptide bond.
A water molecule is used to break the peptide bond. The H joins back to the N, and the OH back to the C.
What is the primary structure of a protein?
The sequence of amino acids found in a protein molecule, refers only to peptide bonds.
What is the secondary structure of a protein?
The coiling (α-helix) or folding (β-pleated sheet) of parts of a protein molecule due to the formation of hydrogen bonds as the protein is synthesised.
What is the tertiary structure of a protein?
The further coiling or folding of a protein due to H bonds, disulphide bonds, ionic bonds, hydrophobic or hydrophilic interactions between the R groups of proteins.
What is the quartenary structure of a protein?
Where proteins polymerise; made of at least two peptide chains.
What are the functions of proteins?
Structural components Membrane carriers/ pores Hormones Enzymes (globular) Antibodies (globular)
What is the R group of an amino acids?
The variable group (1 of 20 atoms)
Describe haemoglobin.
Globular Soluble in water Wide range of amino acids in primary structure Made of 4 polypeptide chains, 2 alpha chains and 2 beta chains Contains a prosthetic groups- haem Transports O2
Describe collagen.
Fibrous Insoluble in water 35% glyceine in the primary structure Made of of 3 polypeptide chains as alpha helices in a rope like structure (triple helix) Structural protein i.e.s bones, tendonsC
Compare a fibrous protein with a globular protein.
Fibres when 3D as opposed to globules Fibrous have fairly regular sequences; globular are more random Fibrous tend to be insoluble in water; globular tend to be soluble
