Structure of Proteins Flashcards
What is primary structure?
The sequence in which the amino acids are synthesised into the polypeptide.
What is secondary structure?
The addition of hydrogen bonds along the backbone of the polypeptide chain. The hydrogen bonds exist between different peptide bonds: The N-H bond which is slightly positive and C-O which is slightly negative.
What is alpha helix secondary structure?
A spiral with the R groups pointing out.
What is Beta sheet secondary structure?
Parts of the chain run along others to form corrugated sheets. Can be parallel or antiparallel. The polypeptide can also form turns; chain folds back on itself.
What is tertiary structure?
The final folded shape of the chain. The 3 dimensional conformation contains regions of secondary structure stabilised in position by interactions between R groups.
What are the possible interactions between R groups?
- Hydrophobic interactions
- Ionic bonds
- Van der Waals forces
- Disulphide bridges
What effects do heat and pH have on polypeptide structure?
Temperature causes denaturation of tertiary structure. The kinetic energy increases causing the chain to shake breaking the ionic bonds and van der waals forces. The change in pH affects the R groups, changing their charge so they can no longer bond together.
What is Quaternary structure?
More than one polypeptide subunits connected by bonding between their R groups.
In quaternary structure what happens when there is a conformational change?
If there is a conformational change on one of the subunits it may affect the others.
What is a prosthetic group?
A non-protein group strongly bonded to a polypeptide unit and essential for function.
