Block 2 Lecture 7 & 8: Protein folding + Chemical Energy Flashcards
To change from primary to secondary structure, which bonds must be formed between amino acid side chains?
Hydrogen bonds
what are the two kinds of secondary strucutre
alpha helix and beta pleated sheet
Tertiary structure involves the collapse of ______ components and the facing outwards of ______ components
the collapse of hydrophobic components and the facing outwards of hydrophilic components
what are the bonds present in tertiary structure between non-polar amino acid side chains, and how strong are they relatively
Van der Waals, weak
what bonds are present between polar side chains in a tertiary structure
hydrogen bonds
what bonds are there between charged amino acid side chains on a tertiary structure, and how strong are they relatively?
ionic bonds, weak
What structure of protein do disulphide bridges form and between what two molecules do they form?
form in a tertiary structure between two cysteine molecules. Is a strong bond
what does a quaternary structure consist of?
two or more polypeptide chains each with their own tertiary structure
homodimer and heterodimer complexes are part of which classification of protein structure?
quaternary
where are membrane anchored and secretory proteins initially translated?
on cytoplasmic ribosomes
What is the name of the particle that recognises the signal peptide when it emerges from the ribosome after being translated?
the SRP, signal recognition particle
what is the function of the SRP, the signal recognition particle?
targets specific receptors in the ER membrane
is the signal sequence found at the C terminus or the N terminus of the polypeptide chain?
the N terminus
what is the process for the translocation of a secretory protein (e.g a hormone) across the ER membrane?
chain is completely translocated and the signal sequence is cleaved off by a signal peptidase.
Do secretory proteins remain insoluble in the ER lumen once they have been translocated?
No, they are effectively solubilised in the lumen once they have been translocated.
What is the process for the transaction of a membrane protein across the ER membrane?
one or more of the hydrophobic segments of the polypeptide chain anchors it in the bilayer
Which of membrane and secretory proteins are moved via transport vesicles from the ER to the Golgi?
Both membrane and transport proteins are moves via transport vesicles from the lumen of the ER to the Golgi
What are the different types of vesicles that operate from the Golgi?
Transport vesicles which move proteins to lysosomes, Membrane vesicles which merge proteins to the membrane of the cell, secretory vesicles which export proteins out of the cell via exocytosis.
Which face of the Golgi are vesicles packaged at?
The trans face of the Golgi