CGIER 42 -Amino Acids/proteins as important buffers Flashcards
Definition of buffer
Buffers are CHEMICAL EQUILIBRIA SYSTEM where the pH varies only slightly when a small amount of acid or base is added to it.
what does a buffer system usually contain
A buffer solution usually contains equal quantities
of a weak acid & its conjugate base.
Buffer system in intracellular fluid (ICF)
Phosphate buffer system
Protein buffer system
Buffer system in extracellular fluid
carbonic acid-bicarbonate buffer system
examples of protein buffer systems
haemoglobin buffer
amino acid buffer
plasma protein buffer
why should there be more conjugate base than weak acid
to counteract the excess acid in the system
what determines the function of an amino acid
the sequence or order of amino acids in the protein molecule
types of peptide
Dipeptide, tripeptide, tetrapeptideOligopeptide, polypeptide or protein
functional group of amino acid
H O
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H2N --- C ------- C ---- OH
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RWhat is histidine responsible for
Side chain of histidine partly responsible
for buffer properties of blood
how amino acids can go from protonated to deprotonated
Low pH - completely protonated
Cation
NH3+ - C - COOH net charge = +1
Intermediate
zwitterion
NH3+ - C - COO-
Net Charge = 0
High pH - completely deprotonated
Anion
NH2 - C - COO-
Net Charge = -1
when is pH equal to pKa
pH of half neutralised solution = when the volume of base given is half the amount of acid
