Notes 2

More power point slides. My hope is that I will be able to add my book notes. Right now, what I've read is not covered in these slides. Once the book and slides are more in sync I plan to alternate. These are from 4/1/09, day 2 of class. {My notes will be in brackets}

Temperature.

Temperature perturbs structures of all classes of macromolecules:
-protein folding and assembly
-nucleic acid secondary structure
-lipid physical state (fluidity)
- protein-nucleic acid interactions

Impportalnce of non-covalent ('weak') chemical bonds in biological structures:
hydrogen bonds, ionic interactions, van der Waals forces, hydrophobic effects
---conservation of 'marginal stability'---

Temperature perturbs rates of physiological activity (Q10 effects)
- a 10*C (deg. Centigrade) change in temperature approximately doubles (or halves) the rates of many biochemical reactions (Q10 = 2)
{this is just the effect of thermodynamics. Other things go on that we'll examine. If you get more than a 2 or 3-fold change in reaction times this is an adaptation. The enzyme is performing better at a specific temperature}

{Remember that cold water holds more gas (boiling water releases it). As temperature rises, solubility decreases.} When body temperature rises, the solubility of oxygen decreases but the demand for it increases.

{Why do we breathe regularly at night? When CO2 levels rise, the pH drops which sends a signal to breathe in.}
As body temperature increases, pH drops ([H+] increases)

Acid-base balance: Rising temperature generally favors dissociation of weak acids leading to an increase in [H+] - a fall in pH.

Temperature determines the physical state of water {ice, water, steam..}

Why species are where they are: biogeographic patterning. And look at the effects of global climate change.


Classes of thermal physiologies
- Determinants of Body (cell) Temperature:

-Ectotherm {external temperature equals internal}
(poikilotherm): {may be different temperature but it is strongly determined by environment}
-Endotherm {generate your own heat}
-Heterotherm {US. Also, a penguin's flippers are colder than its body.. temperature change across body}
-Homeotherm

Breadth of range of thermal tolerance:
-Stenotherm {narrow temperature range}
-Eurytherm {tolerates widely varied temperatures}

Optimal temperatures for function
-thermophile {warm loving extreme}
-psychrophile {cold loving extreme}

{life as we know it occupies a relatively narrow range of temperature}

Phenotypic plasticity: tolerance varies with acclimation


Snails, genus Tegula
different congeners (different species same genus) of Tegula snails live in different vertical positions along an intertidal zone. The same with Littorina {When one species is living in an area that isn't the best - too cold because its above the water where its hotter when it would prefer a cooler lower level at waterline, there is something else at work- perhaps competition of a congener or other organisms}

Thermal tolerance: What sets the limits?
-Thermal tolerance limits: physiology meets biogeography.
...mitochondrial heat resistance and distribution patterns: upper thermal limits for eukaryotic life.
-Acute thermal death (as opposed to chronic stress)
(cardiac failure in marine animals: a possible cause of acute thermal death.

{Isolate mitochondria in test tube and heat. If the mitochondria die, the cell would die in vivo because it is the energy powerhouse of the cell.}

Thermal effects on Mitochondrial Respiration: Arrhenius "break" temperature. respiration rates increase with
***Ask about this and 2 graphs

Mitochondria can live beyond the maximum habitat temperature.
*** what does that mean?