Molecular And Cell Biology Flashcards
Ferritin
A protein which stores, transports and releases iron.
What is Porin?
A protein which sits in the outer bacterial membrane - allows diffusion of certain molecules.
What is a protein’s secondary structure?
Has hydrogen bonding.
Alpha helix - h bonds between amino and carboxyl groups (4 residues apart)
Beta sheet - h bonds between different strands.
What is a protein’s tertiary structure?
Thermodynamically stable - 3D.
Determined by non-covalent interactions.
Where do amino acids go in a tertiary structure?
Polar residues end up on the outside - so can interact with polar water molecules.
Non - polar fold in centre.
What is a disulphide bridge?
Interaction between sulphur atoms in cysteine.
What is a protein domain?
Some proteins fold into different domains - separated by flexible regions.
They carry out a specific function.
What is a protein’s quaternary structure?
Formed of subunits.
2 = dimer, 3 = trimer, 4 = tetramer.
What is methylation?
Post-translational modification
Adds on a -CH3 group.
E.G. on histones to control genome expression.
What is glycosylation?
Post-translational modification
Adds on sugars.
What is ubiquitination?
Post-translational modification.
Adds a 76aa polypeptide to mark protein for degradation.
What is phospholylation?
Reversible
Adds PO3 - uses kinase enzymes.
Regulates enzyme function.
What is protein targeting?
Some proteins contain signals or localisation sequences to show where they need to go.
Some are targeted to cell membrane by the secretory pathway (become channel proteins ect).
What are anchor membrane proteins?
Anchored to membrane by additional hydrophobic groups added on - allows them to be be removed from membrane.
E.g. Ras
