Long, saturated fatty acid tails lipid mobility and membrane fluidity. enhance; increase reduce; increase enhance; maintain maintain; decrease reduce; decrease

reduce lipid mobility
decrease membrane fluidity

When fatty acid tails are saturated, it means that their conformation is perfectly straight becoming easy to compact more and more fatty acids, as they fit perfectly together, and therefore reducing lipid mobility. In turn, if lipid mobility is reduced, the membrane fluidity is decreased because the lipids are too "stiff" together.

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass