Chapter 2: Water, Weak Bonds, and Order Flashcards
Why is water the solvent of life?
Makes some bonds weak while powering the formation of others
Brownian motion
movement due to random fluctuation of energy in the environment –> Thermal noise
+ initiates many biochemical interactions
Why is water polar?
partial positive charge on one end (hydrogens) and a partial negative charge on the other (oxygen)
Why is water cohesive?
H-bonds can from between one molecules H with another molecules O
Provide 6 examples of why water is important?
- Cohesive force
- Surface tension (thx to transient interactions)
- Lubricant (mvmnt + breakdown of particles)
4.Temps regulation
5.Support
F. Waste elimination (nitrogenous waste products)
3 Transient interactions
-electrostatic interactions
-van der Waals forces
Hydrophobic (effect)
Why are transient interaction necessary?
essential in the flow of energy and info.
- forces play roles in DNA replication, protein folding, substrate recognition by enzymes and detection of molecular signals.
Electrostatic Interactions (Ionic Bonds)
-interactions between distinct electrical charges on atoms.
-Energy measured by Coulomb’s law
-weakens in presence of water
-Strongest in non-polar solvent
Hydrogen Bonds
-takes place whenever H is covalently bonded to an electronegative atom (N or O)
-weaker + longer than covalent bonds
- stronger in absence of water
If H-bonds are weak why are they found in DNA?
H-bonds between base pairs stabilize helix + keep info inside. Since the bonds can be broken the helix can be opened for replication or gene expression
- weak interactions are strong to hold DNA but weak enough to open when needed
van der Waals
-non-polar and uncharged molecules interact electrostatically
-interaction due to transient asymmetry, which results in complementary asymmetry
-attractions vs. repulsion dictated by distance between molecules
Hydrophobic forces arise when….
non-polar molecules come into contact with water + are unable to form H-bonds
Why do non-polar molecules group together when in water?
With hydrophobic interactions occurring, when they associate they release water and will no decrease the entropy of water.
Provide a description of Phospholipids
- Amphipathic molecules
- When water is present head groups interact with aqueous medium
- Tail groups interact with themselves
What are the Key functional groups
- Methyl (hydrophobic)
- Hydroxyl
- Carbonyl (Aldehyde & Keto)
- Carboxyl
- Amino
- Phosphate
- Sulfhydryl
