TL: Amino Acids and Proteins Flashcards
Describe the structure of an amino acid
Amino group (NH2)
Central carbon bonded to one H atom
Carboxyl group (C=O and OH)
What is the isoelectric point?
At the isoelectric point, both the carboxyl group and the amino group are likely to be IONISED
(so the amino group becomes NH3+)
(and the carboxyl group becomes C=O and O-)
The amino acid is then called a ZWITTERION
What happens when conditions are more acidic than the isoelectric point?
The amino group becomes PROTONATED
going from NH2 to NH3+
What happens when conditions are more alkali than the isoelectric point?
The carboxyl group is likely to LOSE A PROTON
turning into C=O and O-
Describe the structure of a peptide bond
O=C-N-H
In the formation of a dipeptide, water is given off, name the kind of reaction.
Where does the OH come from?
Where does the H come from?
Condensation reaction.
From the OH on the carboxyl group of one amino acid.
From the amino group of another amino acid.
Name the conditions needed to hydrolyse a protein
Heat under reflux for 24 hours with hot aqueous 6M HCL
Describe the primary structure of a protein
The sequence of amino acids in the polypeptide chain.
Describe the secondary structure of a protein
The hydrogen bonds formed between peptide bonds, making the chain no longer straight.
Either in a Beta - pleated sheet or an Alpha - helix
Describe the tertiary structure of a protein
Different kinds of bonds form between different parts of the polypeptide, coiling and folding the chain.
Name 4 kinds of bonds that hold proteins in their tertiary structure
What groups do they form between?
- Id - Id bonds, formed between two non-polar side groups (CH3)
- Ionic interactions, formed between charged side groups (NH3+ or CO2-)
- Hydrogen bonds, formed between groups with an electronegative atom bonded to a H (OH or NH2)
- Disulphide bridges, formed between two groups that contain sulfur and is the STRONGEST KIND (SH)
