F324 - Polymers and Synthesis Flashcards
What is an amino acid?
Naturally occurring building blocks of protein molecules. The structure of an amino acid contains both the carboxylic acid group and the amino group attached to the same carbon chain.
What is the general formula for an amino acid?
RCH(NH2)COOH
What is a zwitterion?
An ‘internal’ salt of an amino acid, in which the -COOH group donates a proton to the -NH2 group (-OOC-CHR-NH3+).
What is meant by the term isoelectric point?
The pH of a solution in which an amino acid will be at its maximum concentration of zwitterion.
How does the R group on an alpha-amino acid affect its isoelectric point?
R group basic - higher pH isoelectric point
R group acidic - lower pH isoelectric point
How does pH of a solution affect the acid-base properties of an alpha-amino acid?
High pH - amino acid tends to be negatively charged as proton is removed from -NH3+ group (acts as an acid)
Low pH - amino acid tends to be positively charged as -COO- group accepts a proton (acts as a base)
How are polypeptides formed?
Condensation polymerisation between amino acids to form a peptide link.
What type of product is formed during the hydrolysis of a protein (polypeptide) using acidic conditions?
Alpha-amino acid
What type of product is formed during the hydrolysis of a protein (polypeptide) using alkaline conditions?
Alpha-amino acid reacts with excess alkali and forms its carboxylate salt.
What is an optical isomer?
Molecules that are non-superimposable mirror images of each other about an organic chiral centre.
What affect do optical isomers have on plane polarised light?
The two isomers (known as enantiomers) rotate the plane of polarised light in opposite directions.
What is a chiral centre?
A (carbon) atom in a molecule attached to four different groups.
Optical isomers and E/Z isomers are examples of which type of isomerisation?
Stereoisomerism
With the exception of glycine, what do all alpha-amino acids have at the alpha-carbon atom?
A chiral centre
What is meant by condensation polymerisation?
A polymerisation reaction in which the monomers are joined together by condensation reactions. Monomers can be different molecules.