BIOCHEM lecture 1-10 Flashcards
strength between non-covalent interactions
permanent dipoles> dipole-induced dipole> London dispersion forces
The water
molecule is non-
linear and
carries a
permanent
dipole moment.
The “van der Waals envelope” is the
effective “surface of the molecule”.
Two atoms from different molecules rarely come closer together than the sum of
their van der Waals
radii
exception to van der waals radii being the closest two atoms can get
Hydrogen
unit conversion for vdW radius
10 Å = 1 nm = 10 -9 m
when water is ice it
interacts tetrahedrally with four other molecules
D-H =
weakly acidic “donor” group, such as O-H, N-H
A =
weakly basic “acceptor” atom such as O, N
D-H…A
hydrogen bond
The permanent dipoles of water molecules interact very favorably with charged ions in
solution,
forming a “hydration shell”.
no difference in enthalpy (entropy drive) in a
transfer of hydrocarbaons from water to nonpolar solvents
amphiphillic/amphipathic
have both polar and non-polar segments
clustering lipids
increase the entropy of a system (less rotational restriction)
H-bonding within water facilitates its
ionization
H+ should be written as
H3O+ technically
1 liter of water there is
55.5 moles
Kw[10E-14]=
[H+ 10E-07][[OH- 10E-07]
HH equation
pH = pKa +log ([base]/[acid])
protons can be used to:
- Induce a large conformational change of a protein.
- Store energy – as a proton concentration difference
across a membrane
The pH of fluids surrounding
cells, and of the cytosol inside
the cell, is around 7.
However, in the organelles
called endosomes, the pH is
lower. -> used by influenza virus to infect a host cell bc pH differences inducesconformational change in surface protein
protons cannot cross a
lipid membrane
periplasm
the space between two membrane of bacterial cells
low proton concentration in
cytoplasm
