1.6 - Proteins Flashcards
(13 cards)
Globular vs Fibrous proteins
Globular proteins:
- spherical structures
- hydrophobic parts of the protein fold inwards
- water soluble
- hydrophilic on surface
function is to mesaage, transport proteins, enzymes
Fibrous proteins:
- long chains
- water insoluble
- structural proteins
What are Fibrous proteins?
Form long chains which run parallel to one another and they’re linked by cross bridges and become very stable molecules
Test for proteins
- Place a sample of the solution to be tested in a test tube and add an equal amount of NaOH
- add a few drops of very dilute copper (II) sulfate solution and mix gently
- a purple colouration is formed in the presence of peptide bonds and hence a protein or it remains blue
Quaternary Structure of Proteins
May contain non-protein groups associated with the molecules ((haemoglobin) and the sequence of amino acids determines the 3D shape and this is due to the combination of a number of different polypeptide chains
Bonds within the tertiary structure
- disulphide
- ionic
- hydrogen
Tertiary Structure of Proteins
alpha helices can be twisted and folded even more to give the complex a specifc 3D structure of each protein and is maintained by a no. of different bonds and it happens depending on the primary structure
Secondary Structure of Proteins
the linked amino acids make up a polypeptie bond and they have amino and CO groups on either sides and the hydrogen of the nitrogen group has an overall positive charge while the CO has a negative charge and these 2 have weak bonds and they cause the peptide chain to twist into a 3D shape
Formation of a peptide bond
Primary structure of proteins
polymerisation occurs through a series of reactions and the resulting chain of many hundreds of amino acids is a polypeptide and this sequence of the amino acids forms the primary structure of any protein (determined by DNA)
General structure of an amino acid
Formation of a peptide bond
- Amino acid monomers can combine to form a dipeptide
- water is made through the -OH from the carboxyl group of one amino acid with an -H from the amino group of another amino acid
- 2 amino acids become linked by a new peptide bond between the carbon bond of one amino acid and the nitrogen atom of another
4 chemical groups that amino acid carbon atoms can attach to
- amino group (NH2)
- carboxyl group (-COOH)
- hydrogen atom
- R (side) group - a variety of different chemical groups
Structure of an amino acid
basic monomer units which combine to make up a polymer (polypeptide)
