Ianowski - theme 2

Question 1

Gain/loss of volume in relation to gain/loss of osmolytes:

Answer 1

More osmolytes = greater volume. Think about the movement of water.

Question 2

Loop of Henle responds to changes in water availability:

Answer 2

In restricted water conditions, 1200 osm (increased permeability). In high water conditions, 800 osm (no water permeability).

Question 3

ICF of osmoconformers: what makes up the 1000 mOsm?

Answer 3

400 mOsm of universal solutes, 600 mOsm of organic osmolytes.

Question 4

Organic osmolytes vs macromolecules in cells:

Answer 4

Most do not disturb them; some stabilize them.

Question 5

Types of osmoconformers:

Answer 5

Stenohaline, euryhaline

Question 6

Stenohaline osmoconformers:

Answer 6

Restricted to a narrow range of salinity. Cannot regulate osmolytes.

Question 7

Euryhaline osmoconformers:

Answer 7

Tolerant of salinity changes. Can regulate osmolytes. Good at surviving in intertidal zones.

Question 8

Halobacterium - alternative compatible osmolyte strategy

Answer 8

Accumulate huge levels of KCl (7M) to survive in 1M NaCl. Needs massive AA replacement to function here. Stenohaline.

Question 9

Dunaliella: a euryhaline conformer

Answer 9

Regulates intracellular osmolytes concentration. Compared to halobacterium, genetically simple, because AAs don’t need to be modified.

Question 10

Mosquito osmoconforming/regulating:

Answer 10

When water evaporates from larvae, the bb has to survive the osmolarity change. Regulates at low concentrations, conforms at high concentration. Proline shows massive decrease at high solute concentration while other osmolytes stay about the same.

Question 11

Stenohaline sharks: special lil buddies

Answer 11

Stenohaline sharks are the only vertebrates that osmoconform. Sharks use perturbing osmolyte urea that is balanced out by TMAO in a 2:1 ratio. TMAO is very stabilizing; urea is very not.

Question 12

Euryhaline sharks:

Answer 12

Can penetrate freshwater, but it’s energy expensive. They pee a lot.