Module 2 Flashcards
(25 cards)
Passive role of Water
The structure of biomolecules form in response to interaction with water. For example, protein folding is driven to bury hydrophobic residues
Active Role of Water
Water is a participant in many biochemical reactions. For example, peptide bond formation releases a water molecule
What do Oxygen and Hydrogen Differ in
ELectonegativhities
What is more electronegative
Oxygen is more electronegative than hydrogen, giving water a permanent dipole
What abilities does dipole give
Form electrostatic interactions with charged molecules
Form hydrogen bonds (including with other water molecules)
Hydrogen Bonds
Electrostatic interactions between an electronegative atom with a hydrogen (donor) covalently linked to another electronegative atom with a free electron pair (Acceptor)
Hydrogen bonds
Relatively weak
About double the length of a covalent bond
Strength depends on geometry
Example: Antiparallal beta sheets are stronger than parallel because there is better geometry of hydrogen bonding
How many hydrogen bonds can a water molecule donate or accept
2
Heat of Vaporization
Amount of heat required to vaporize a liquid at its boiling point
Specific Heat Capacity
Amount of hear required to raise the temperature of a substance by one degree
Ice
In ice water molecule participates in 4 hydrogen bonds with other water molecules
Ordered arrangement of ice has a lower denser than liquid water as a consequence Ice floats on water
Hydrophilic
Water loving (Molecules are polar)
Hydrophobic
Water fearing (Molecules are non polar)
Amphipatic molecules
Contain both hydrophobic and hydrophilic
Non covalent forces influence
Formation and stabilization of structures of biomolecules
Recognition/interactions between biomolecules
Binding reactants to enzymes
Non covalent interactions enable
Transient and dynamic interactions
Flexibility of structure and function
Non Covalent interactions within biomolecules includes
hydrogen bonds
Ionic (Electrostatic interactions)
Hydrophobic interactions
Van der Waals Interactions
Hydrogen Bonds
Many of the functional groups with biomolecules have hydrogen bonding capacity
Hydrogen bonds impact on biomolecular structures
Critical for specificity and NOT for Formation of biomolecular structures
Hydrophobic effect
Drive to have polar regions to interact with water and non polar regions shielded away from water
Thermodynamics of the Hydrophobic effect
Water molecules around hydrophobic molecules are more ordered than they would be in pure water. Such as an introduction of the non polar molecule causes decrease in the entropy of water
The association of non polar molecules released some of the ordered molecules resulting in an increase in entropy of wattle
Entropy in a polypeptide
Folding of a polypeptide decreases the entropy of the polypeptide but increases the entropy of the associated water
Strong acids and bases
Completely dissociate with water
Weak acids and bases
Do not dissociate completely in H20
