Biochemistry: Properties of Water & Buffers

Flashcards covering the properties of water, buffers, and the Henderson-Hasselbalch equation.

Why is water a good solvent?

Water is an excellent solvent for compounds that have ionic charges or can form hydrogen bonds.

What are amphiphilic molecules?

Molecules that contain both hydrophilic and hydrophobic regions.

Give examples of amphiphilic molecules.

Chemicals composing cell membranes, soaps, and detergents.

What are micelles?

Organized, macromolecular structures formed by amphiphilic molecules dispersed in water.

What does water dissociate into?

Hydroxyl ion (OH-) and proton (H+).

What is the ionization constant of water (Kw)?

10^-14 at 25°C.

What is the pH and pOH of neutral water?

pH = pOH = 7.0.

What are buffers?

Combinations of acids and bases that resist changes in pH.

What is the pH of most parts of our body?

7.4

What is the buffer system inside the cell?

H2PO4- / HPO42-

What is the buffer system outside the cell?

CO2 / HCO3- (bicarbonate)

How is pH regulated in our blood?

By varying the concentrations of CO2 and HCO3-.

What happens during metabolic acidosis?

Increased CO2, equilibrium shifts right, [H+] increases, pH decreases.

What happens during respiratory acidosis?

Increased CO2, equilibrium shifts right, [H+] increases, pH decreases.

What happens during respiratory alkalosis?

Decreased CO2, equilibrium shifts left, [H+] decreases, pH increases.

What is the Henderson-Hasselbalch equation used for?

To determine the pH of a buffer.

What are buffers made of?

Acid and its conjugate base.

How do you find the pKa when preparing a buffer?

Find the pKa value of the acid in a general chemistry textbook.

How can the Henderson-Hasselbach equation predict whether a particular functional group will be charged or not?

Plugging known values into the Henderson-Hasselbalch equation to determine if a functional group will be charged or not.