proteins Flashcards
What are the 3 stop codons?
UAG, UAA and UGA.
What are the 4 classes of AA’s?
Acidic, basic, un-charged polar and non-polar.
What is primary structure?
The sequence of AA’s in a polypeptide chain.
What is secondary structure?
Alpha helices and beta-pleated sheets. Both are held together by H-bonds.
What is tertiary structure?
A polypeptide folding in 3D space. Dependent on: Van der Walls, ionic interactions, H-bonds, s-s and hydrophobic interactions. Eg, transferrin.
What is quaternary structure?
The arrangement of individual polypeptide chains in a multi-subunit protein. Eg. haemoglobin.
What is the smallest AA?
Glycine.
What happens when a protein is denatured?
Secondary and tertiary structure is lost so the protein loses its conformation.
Name 6 causes of protein denaturation.
Acids, heat, solvents, chaotropic reagents and s-s reducers.
Where does glycosylation occur?
Golgi or ER.
What is HbA1c?
A GP that is a marker of diabetic control. The higher this is, the higher the risk of developing complications.
What is the function of lipoproteins?
Transport water insoluble fats and cholesterol in the blood - LDL or HDL.
Give an example of co-operative binding.
When 1 haem group binds O2 this changes the conformation of the other subunits so that they can bind O2 more easily.
Which point mutation causes sickle-cell anaemia?
A - T causes hydrophilic glutamic acid to be changed for hydrophobic valine. HbS gives up O2 in the tissues more easily than HbA.
Which repeating unit is collagen composed of?
glycine-X-proline. X can be alanine, hydroxyproline or lysine. Collagen is a triple helix.
