Week 1 RAS live session 1

Question 1

What is the DNA backbone

Answer 1

1) A phosphate backbone is the portion of the DNA double helix that provides structural support to the molecule.

Question 2

2) What is the classification of the side chains?

Answer 2

2) Amino acids
a) Non-polar
b) Polar charged
c) Polar non charged

Question 3

3) Classification of protein structure – general definition of each?

Answer 3

3) Secondary structure If the same phi-psi angles occur several times in
succession in the chain helical structures are formed
some with recurring patterns of hydrogen bonds (directional polar interactions between the main chain -
NH and C=O groups) that stabilize repeating secondary structures – the alpha helix and the beta strand. The secondary structures assemble – with intervening loop regions - to give the tertiary structure. Tertiary structure = arrangement of all atoms in the subunit, arrangement of the alpha-helices and betasheets, side-chains and any additional cofactors

Question 4

4) What are the key forces that hold proteins together? Can you illustrate where they come in?

Answer 4

4) different bonding:
a) Ionic bonding: The force can be repulsive (same charges) or attractive (opposite charges).
b) Hydrogen bonds: Hydrogen bonds are highly DIRECTIONAL!
c) Van der Waals interactions: Any atom in contact with any other.
i) Dipole – dipole interactions
ii) Dipole – induced dipole interactions
iii) London dispersion forces (transitory dipoles)
d) Disulphide Bonds

Question 5

What is the primary structure of a protein?

Answer 5

Amino acids are linked by peptide bonds to form linear chains called
polypeptides. Polypeptides have a regularly repeating unit called the backbone and a variable part - the side chains.Polypeptides have direction and the sequence is written and numbered from the N-terminus to the C-terminus.