Ianowski - theme 1

Question 1

Obligatory osmotic exchange:

Answer 1

Water exchange happens whether you want it to or not, through breathing and excretions.

Question 2

Ions in order of most to least stabilizing, most to least solubilizing

Answer 2

K, Na, H, Ca

Question 3

K+ in cells:

Answer 3

100-150 mM of K+. More than 180 mM inhibits cell function. It’s right in the middle of the Hofmeister series, so it is fairly protein stabilizing.

Question 4

Regulating ion composition of cells:

Answer 4

ATP regulates ion concentrations by ETC.

Question 5

Regulating osmolarity of cells:

Answer 5

Most cell membranes are permeable to water, so it’s hard to control that. Some epithelial cells can control osmolarity. WATER CANNOT BE ACTIVELY PUMPED.

Question 6

Units of osmolarity:

Answer 6

mol/L.
1 mol of glucose = 1 osm
2 mol of NaCl = 2 osm

Question 7

Units of osmolality:

Answer 7

osmol/kg

Question 8

Sensitivity to volume change in cells:

Answer 8

Can detect changes of 3%.

Question 9

Gain/loss of inorganic molecules:

Answer 9

Not good for protein function. Vmax sucks ass at high concentrations.

Question 10

Organic molecules in cells:

Answer 10

Three kinds -
Carbs (sorbitol)
AAs and derivatives (proline)
Methylamines (TMAO)

Can be perturbing or compatible.

Question 11

Who uses compatible osmolytes?

Answer 11

EVERYONE. From archaea to higher mammalian tissues (brain, kidney).

Question 12

Different levels of conformation/regulation:

Answer 12

Perfect, strong, weak, limited