3.1.4.1 Proteins Flashcards
What are the monomers that make up proteins?
Amino acids
What is the structure of an amino acid?
See card
How many naturally occurring amino acids are there?
20
What changes from amino acid to amino acid?
The side chain is the only thing that changes
How are two amino acids joined?
By a peptide bond via a condensation reaction
Peptide bond: See card
What are the units of protein?
Peptide = one
Dipeptide = two
Polypeptide = many
What is the primary structure of amino acids?
The order of the amino acids in the polypeptide chain
What changes the properties of a protein?
The order of the amino acids, not the type
What is the secondary structure of proteins?
The alpha helix or beta pleated sheet
This is created by hydrogen bonds which aren’t bonded but are attracted which bend the polypeptide chain
What is the tertiary structure of proteins?
The further folding of the alpha helix or beta pleated sheet
It is held together by hydrogen bonding, ionic bonding, a disulfide bridge and hydrophobic interactions
What are hydrophobic interactions in the tertiary structure of proteins?
When clusters of hydrophobic molecules bend the chain around them to block any water
What is a disulfide bridge?
When sulfur atoms in the side chains bond
This is one of the strongest types of bond
What is the quaternary structure of proteins?
When 2 or more polypeptide chains are joined together in a fibrous or globulous structure
Fibrous = long intertwined protein chains
Globulous = when blocks of polypeptide chains are put together
How do you test for proteins?
Put a small amount of sample in test tube, add an alkali and shake thoroughly, add drops of the Biuret reagent and mix gently after each drop, allow mixture to stand
A violet colour indicates a protein presence
Blue indicates no presence- colour of copper sulfate
What does an alpha helix/beta pleated sheet look like?
See card
