Today Q10 revisited Enzyme adaptation Biochemical Adaptation to Temperature Change – enzymes, membranes and heat shock proteins Mechanics of heat gain and loss Convection Conduction Evaporation Radiation Definitions of the “therms” Keeping Warm --- the extremes

Membrane Changes In heat – more cholesterol, more satuated fatty acids In cold – more polyunsaturated fatty acids (PUFAs),

Stress Proteins or Heat Shock Proteins are produced when an organism is subjected to environmental stresses including heat, high salinity, desiccation, heavy metal pollution. Hsp 70 and hps 60 proteins act to protect enzymes by folding around them to prevent changes in weak bonds and denaturation.

Conduction varies with the area exchanging heat, the distance between the source and the sink and the types of materials in contact. Q = kA(t2-t1) l

Convection is the special case of conduction where one or both of the exchangers are fluid and moving. In animal systems, concurrent conduction systems are modified to form very efficient counter current systems.

Radiation Bodies radiate electromagnetic energy proportional to the 4th power of the absolute temperature of the surface. The hotter the surface, the shorter the wavelength radiated. At biological temperatures, approximately 300oK, our bodies emit energy in the infrared range, but visible light.

Evaporation One of the most effective ways to loose heat is to use it to heat water from a liquid to a gaseous state. This requires a lot of heat energy, 585 calories/ gram. Many animals sweat, or pant to remove heat. Camels will sweat when they are well watered, but a dry camel instead allows it body temperature to fluctuate + 3.5o.

Extremophiles – bacteria, diatoms and protozoa have been found living in sea ice in the arctic and antarctic. The presence of these organisms suggests that there may also be live on ice covered plants like Europa shown here.

Temperature Regulation in Heterotherms and Homeotherms First Response – Behavioral Conduction and Anatomy – Big Ears Counter Current circulation in Fish Sexy Dolphins Insect Flight Warm-up Brown Fat and Hibernation Fever The Thermostat