passive water role:
The structure (hence function) of biomolecules forms in response to interaction with water. EX: protein folding is largely driven in an effort to bury hydrophobic residues away from water.
active water role:
Water is a participant in many biochemical reactions. EX: peptide bond formation releases a water
Oxygen is more electronegative than hydrogen, giving water a permanent dipole. The dipole of water influences its ability to:
-Form electrostatic interactions with charged molecules.
-Form hydrogen bonds (especially with other water molecules).
Hydrogen bond strengths and geometry:
-Hydrogen bonds are relatively weak (5% of covalent bonds)
-hydrogen bonds are around double the length of covalent bonds
-The strength of a hydrogen bond depends on its geometry.
Heat of vaporization:
The amount of heat required to vaporize a liquid at its boiling temp
Specific heat capacity:
The amount of heat required to raise the temperature by one degree.
What types of molecules are more soluble in water?
Molecules that carry a charge (positive or negative → ions, polar groups).
Molecules that can form hydrogen bonds (donors or acceptors).
Definition of…
-Hydrophilic
-Hydrophobic
-Amphipathic
Hydrophilic: Water loving (polar)
Hydrophobic: Water fearing (non polar)
Amphipathic: Contains both hydrophobic and hydrophilic portions, EX: fatty acids
What is the hydrophobic drive and why is it important in biology?
Hydrophobic drive: Nonpolar molecules cluster together to avoid water.
It is a primary force in the formation and stabilization of biomolecular structures (e.g., protein folding, membrane formation).
What are the different types of non-covalent forces involved in the formation and stabilization of biomolecular structures?
hydrogen bonds, electrostatic Interactions, van der Waals interactions and hydrophobic interactions.
Describe how the structure of water contributes to its properties as a solvent.
Collectively, molecules or groups that carry a charge and/or have hydrogen bonding capabilities will interact favourably with water, which is to say they will be hydrophilic.
Non-covalent forces influence:
-Formation and stabilization of structures of biomolecules
-Recognition/interactions between biomolecules
-Binding of reactants to enzymes
Non-covalent interactions within biomolecules include:
-Hydrogen bonds
-Ionic (electrostatic) interactions
-Van der Waals interactions
-Hydrophobic interactions
The water molecules around hydrophobic molecules are more ordered than they would be in pure water, as such the introduction of the non polar molecule causes a INCREASE OR DECREASE in the ENTROPY of water?
DECREASE
The lower the pKa the _________ the acid will be
Stronger
What are buffers?
Solutions that are able to resist changes in PH with the addition of acid or base
Amphoteric meaning
A molecule capable of donating and accepting protons, thus able to serve as an acid or a base.
Which non-covalent forces contribute to the structure and stability of biomolecules?
Hydrogen bonds → stabilize helices, sheets, base pairs
Electrostatic interactions → ionic bonds/salt bridges between charged groups
Hydrophobic interactions → nonpolar groups cluster inside, driving folding
Van der Waals interactions → weak, numerous forces that stabilize close packing
