Proteins Flashcards
What are the monomers from which proteins are made?
Amino acids
Are R groups polar or non- polar, hydrophilic or hydrophobic?
Some are polar (and therefore hydrophilic) and some are non-polar (and therefore hydrophobic).
How are dipeptides formed?
The condensation of two amino acids (water is also formed).
How are polypeptides formed?
The condensation of many amino acids (water is also formed).
Where are peptide bonds formed in a cell?
The ribosomes.
Describe the biochemical test for proteins.
- Mix the test solution with Biuret’s reagent (which contains dilute Sodium Hydroxide and dilute Copper Sulphate)
- If protein is present then the solution will change from blue to purple
What does the amino acid sequence determine?
The tertiary structure (shape) of a protein.
What does the tertiary structure (shape) of a protein determine?
It’s function
What are the levels of protein structure?
Primary structure, secondary structure, tertiary structure, quaternary structure.
What is the primary structure of protein?
The order/sequence of amino acids in the polypeptide chain.
What is the seondary structure of protein?
The regions stabilised by H bonds between C=O and N-H groups between amino acids.
What is the tertiary structure of protein?
- The regions of secondary structure and other twisting and folding.
- The tertiary structure is held together by a number of different bonds between the R-groups of amino acids:
- Disulphide bridge
- Ionic bonds
- Hydrogen bonds
- Hydrophobic interactions
What is the quaternary structure of protein?
More than one polypeptide chain associated together:
- The different polypeptide chains are held together by hydrogen bonds, ionic bonds, disulphide bridges and hydrophobic interactions (the same four types of bonds as in the tertiary structure).
- There may also be non-protein groups associated with the protein called prosthetic groups.
What does a functional protein contain?
One or more polypeptides.
