Amino acids and polymers Flashcards
What are the functional groups in an amino acid?
1) Amino group (NH2)
2) Carboxyl group (COOH)
Also R group
Why are amino acids amphoteric? (react with both acids and bases)
The amino group is basic and the carboxyl group is acidic
How many naturally occuring amino acids are there?
About 20
What makes amino acids different to each other?
different R groups
Whats an alpha amino acid?
General formula?
An amino acid that has an -R group bonded to a carbon atom that directly carries the amino and carboxyl group.
They join together to form proteins
general formula: RCH(NH2)COOH
What is a zwitterion?
What is the isoelectric point?
a both positively and negatively charged ion
amino acids can act as zwitterions, they are electrically neatral overall
the isoelectric point is the pH at which the amino group and the carboxyl group are most likely to be charged
Why do different amino acids have different isoelectric points?
they have different r groups
how does ph affect amino acids?
at lower pH the amino group is more likely to be protonated, at higher pH the amino group is more likely to have lost its proton
How does the existence of zwitterions affect amino acids properties?
it means that amino acids are readily soluble in water ( a polar solvent)
it means that amino acids have quite high melting point and are solid at room temperature
what do amino acids join together to form?
polypeptides/proteins
How many amino acid unites in a protein/polypeptide?
proteins - more than about 20, most common proteins contain over 100 amino acid units
polypeptide - less than about 20 amino acid units
How are proteins made?
They are made by condensation polymerization reactions of amino acids
In these reactions amino acids join together to form a longer molecule, water is also made for each amino acid added
proteins are examples of natural polymers
How do amino acids join?
The amine group of one amino acid reacts with the carboxyl group of the next amino acid to form a dipeptide. A water molecule is lost and a peptide link (-CONH-) is formed
How does extreme temp or pH affect a protein?
They break the hydrogen bonds and disrupt the structreu of the protein. it becomes denatured
what reaction breaks down a protein into amino acids
how does this take place?
hydrolysis, reverse of condensation polymerisation
1) protein is reacted with 6 mol dm^-3 HCl for 24 hours
2) reaction mixture is neatralised
