Acids/ Bases/ Buffers (water)

Question 1

What is the hydrophobic effect?

Answer 1

“the process in which non polar molecules in aqueous solutions are driven together because of the resulting increase in entropy of water molecules”

Simply: water can dissolve polar or charged molecules and powers the organization of hydrophobic/non polar molecules

Entropy: low when ordered (mixed) high when less ordered (seperated)

Question 2

Why is pH important in living systems?

Answer 2

pH determines the elctrostatic environment of biomolecules

affects weak bonds that maintain their structure

impacts interactions between biomolecules

Question 3

What is a buffer?

Answer 3

an acid-base conjugate pair that resists changes in the pH of a solution

make using acetic acid (pKa 4.476 +/- 1)

Question 4

Why are buffers important in biological systems?

Answer 4

biomolecules are very sensitive to pH, and small changes may alter function. Buffers work by resisting drastic changes in pH, so biological systems are maintained

Question 5

are amino acids hydrophilic, hydrophobic, or amphipathic?

Answer 5

both. 9 are hydrophobic, 11 are hydrophilic

Question 6

phospholipids are ________

Answer 6

amphipathic

Question 7

carbohydrates are hydro______

Answer 7

hydrophilic, because theyre polar and contain OH groups

Question 8

Nucleic acids are hydro - ?

Answer 8

hydrophilic

Question 9

Structure of water?

Answer 9

2 H atoms linked covalently to an O atom
- electronegative and polar
- Dynamic, partly ordered, cohesive structue

Dynamic = H bonds break and reform (many interactions)

Question 10

How do Hydrogen bonds form in water?

Answer 10

their polarity allows for the H’s and O’s of adjacent molecules to form bonds (4 H bonds w/ surrounding molecules)
- making them stick together

Question 11

How do ionic/ electrostatic/ salt [bridges] bonds form?

Answer 11

interactions between completely negative and completely positive charges
- water shield/weakens electrostatic interactions so it can dissolve salts

Question 12

How do Van der waals interactions work?

Answer 12

depends on transient symmetry in electrical charge around an atom; induces a complementary e- assymetry of a neighbouring atom
- individually weak, collectively powerful (SA)

Question 13

Chose buffer systems that have pKa’s closest to

Answer 13

that of the biological system

ex blood = 7.4, uses carbonate

Question 14

pH = pKa + log [A]/[HA]
is what equation?

Answer 14

Henderson-Hasselbalch