Proteins Flashcards
What are proteins?
Condensation polymers of amino acids
What bonds join amino acids to form a protein?
Peptide bonds
What reaction breaks down proteins to form amino acids?
hydrolysis
If you join two different amino acids, what is formed?
Two different dipeptides
What conditions are required for the hydrolysis of proteins?
Add aqueous 6 moldm-3 HCl and then heat the mixture under reflux for 24 hours
What are the 4 different structures of proteins?
Primary
Secondary
Tertiary
Quaternary
What is the primary structure of a protein?
Sequence of amino acids that make up a polypeptide chain
What is the secondary structure of a protein?
Hydrogen bonds form between peptide links and either coils into an alpha helix or into a beta pleated sheet
What is the tertiary structure of proteins?
Extra bonds form between the polypeptide chains and this causes it to become 3D
What are the two types of bonds that hold proteins in shape?
Hydrogen bonding
Disulfide bonding
How does hydrogen bonding occur in proteins?
The hydrogen atom has a partially positive charge due to the increased electronegativity in the other atom. The hydrogen is then attracted to lone pairs of electrons on adjacent polar groups and a hydrogen bond is formed
Where does a disulphide bond occur?
Between residues of the amino acid cysteine as it contains a thiol group which loses its H atom and joins to form a disulfide -S-S- bond
What factors can affect the bonding in a protein?
Temperature and pH
