Chapter 2: Water, Weak Bonds and the Generation of Order out of Chaos Flashcards
What is Brownian motion? What is the most common medium?
Brownian motion is the movement of molecules powered by random fluctuations of environmental energy—thermal noise. Water is the most common medium.
Name two purposes of Brownian motion.
- Brownian motion of water initiates many biochemical interactions.
- Brownian motion is a vital source of energy for life.
What are the charges on the parts of a water molecule? (Just general)
The oxygen atom carries a slightly negative charge and the hydrogen atoms carry slightly positive charges.
What is the structure of water? How many such strong hydrogen bonds can be formed with neighbouring molecules? When do these bonds occur?
Its oxygen atom has two lone pairs of electrons and two hydrogen atoms attached. Four such strong hydrogen bonds can be formed with neighbouring molecules. As observed in ice, strong hydrogen bonds tend to form when the hydrogen atom is aligned with the lone pair of electrons in the acceptor atom.
What are typically the hydrogen acceptors?
Oxygen.
What does the polarity of water allow for? What two things does this account for?
The polarity of water allows the formation of hydrogen bonds between water molecules. This accounts for the cohesiveness of water. The polarity of water also accounts for its ability to dissolve many important biochemicals.
What does the inability for water to dissolve non-polar molecules result in?
The inability of water to dissolve non-polar molecules results in an important organizing principle called the hydrophobic effect.
What do weak bonds permit?
Weak bonds permit dynamic interactions that form the basis of biochemistry and life itself.
What are electrostatic interactions?
Electrostatic interactions, also called ionic bonds or salt bridges, are the interactions between distinct electrical charges on atoms.
What is Coulomb’s law (formula)? What do the symbols represent and what is it used for?
{E = [k(q1)(q2)]/Dr}. E is the energy, q1 and q2 are the charges on the ions, D is the dielectric constant, r is the distance between the two ions, and k is the proportionality constant. It is used to find the energy of an electrostatic interaction.
What is the dielectric constant in a vacuum? What is it in water? What does this show?
The dielectric constant is 1 in a vacuum and 80 in water. Thus, water weakens electrostatic interactions.
How does water disrupt hydrogen bonds between two molecules?
Water disrupts hydrogen bonds between two molecules by competing (substituting) for the hydrogen-bonding capability.
How can non polar and uncharged molecules interact electrostatically?
Nonpolar and uncharged molecules can interact electrostatically with van der Waals interactions.
What is the basis of van der Waals interaction?
The basis of the van der Waals interaction is that transient asymmetry in the electron distribution of one molecule will induce complementary asymmetry in a nearby molecule. Most importantly, VDW interaction is distance dependent.
What bonds contribute to the stability of the DNA double helix? Why is the strength of these important?
Hydrogen bonds contribute to the stability of the DNA double helix. However, these bonds are weak enough to be broken by the enzymes of DNA metabolism, thereby allowing access to the genetic information. (Weak means feasibility for forward and inverse processes)
