Question

2. List some familiar adaptations animals have to reduce the effects of temperature extremes on their many vital, enzyme-catalyzed reactions. 3. In general, the rates of chemical reactions double for every 10 degrees (Celsius) increase in temperature. What changes at the molecular level account for slower reaction rates of enzyme- catalyzed reactions at high temperatures? (Hint: enzymes are protein molecules. What happens to protein molecules when they are heated?) Why are enzyme catalyzed reactions also slower at low temperatures? (Hint: What happens to the motions of enzyme and substrate molecules as they cool? Why does this affect the rate at which enzyme and substrate react?) 4. The binding of enzymes with their substrates is most efficient under certain (so called "optimal") pH conditions. Human cells and body fluids contain hundreds of natural buffer systems that serve to keep pH at or very near optimal levels. Potato cells and human cells are both living and so have thousands of biochemical reactions in common. From the results of your catecholase experiment, what value of pH is most likely to be found inside human cells?

Answer 1

2. Some common adaptations are:

Burrowing: Some animals like moles, gopher, ground squirrels etc., form burrows. The temperature below the ground level is lower and helps them with combating the heat.

Low water needs: One classic example is of the camel. They do store water and fats to facilitate their journeys in the deserts, but they minimize water loss by lack of sweating and urination.

Releasing heat: Birds deal with extreme heats by reducing the insulation provided by the feathers and releasing heat.

Keeping the bodies cool is essential for the enzymes to function properly.

3. Enzymes are proteins in nature. It is well known that there is a strong correlation between protein structure and function. At high temperatures, proteins get denatured and lose their function. That is why enzymatic reactions do not take place at high temperatures.

Enzymes possess certain flexibility which allows them to move within and across the cells. Lowered temperatures reduce or diminish this flexibility and the enzyme and substrate movements become slower. This causes enzymatic reactions to slow down at lower temperatures.

4. Normally the pH within the cells is 7.0-7.4 (neutral pH). However, this changes with the type of cells and their functions.

Example: The pH of skeletal muscle cells is 6.8-7.1.

The pH of cells in the gastric lining is 1.5-3.5.