Section 38.3 (Exam 3) Flashcards
Biological Processes Are Temperature-Sensitive
What is the range of temperatures in which most cells can survive?
a narrow range of 0-45 Celsius
What happens to cells below 0 Celsius?
Ice crystals form and damage cell structures
How do some cells survive below 0 Celsius?
Some animals have antifreeze molecules in their blood that help them resist freezing; others can survive freezing
What is one example of a frog that survives below freezing temperatures?
Rana sylvatica
Urea and glucose accumulation act as cryoprotectants
Intracellular water redistributed to ECF
Why is redistributing intracellular water to the ECF effective for countering freezing?
If intracellular water freezes it can puncture cell structures. By relocating it, it avoids damage to cell structures.
Why do cells die above 45 Celsius?
Proteins begin to denature and lose function
What are example of organisms that can survive above 45 Celsius?
Specialized algae that grows in hot springs at 75 Celsius
Some archaea live at near 100 Celsius
What are heat shock proteins (HSPs)?
Chaperone proteins that stabilize other proteins and prevent denaturation
What range do most cells survive in, and what do they have that allows them to do so?
0-45 Celsius
Thermoregulatory adaptations
Biochemical reactions are temperature-sensitive. How does this affect their rate of reaction?
The rate of reaction increases as temperature increases
What is the Q_10?
A way of describing temperature sensitivity of a reaction.
Rate of reaction at one temperature divided by rate of the same reaction at a temperature 10 degrees Celsius lower.
If a reaction is not temperature sensitive, what is its Q_10?
1, because the rate of reaction 10 degrees lower or higher would be the same rate.
What does it mean if Q_10 is 2?
As the temperature increases by 10 degrees Celsius, the rate of the reaction doubles.
What range of Q_10 do most biological reactions have?
2-3
Why does change in body temperature disrupt physiology?
Not all biochemical reactions have the same Q_10.
Why can shifting the reaction rate for one reaction disrupt the entire biological network?
Products of one reaction are reactants for other reactions.
All the reactions are linked in complex networks.
If one product is produced incorrectly, all sequential reactions will not occur correctly.
Some animals couple their body temperature to the environmental temperature, such as fish. How do fish remain active in differing temperatures?
In the cold, fish can acclimatize, and have a higher metabolic rate
What is one mechanism for acclimatization?
Expressing isozymes
What are isozymes?
Different forms of an enzyme that have different temperature optima
What must the body do in response to hyperthermia (overheating)?
reduce heat-generating muscular work and increase heat loss
How does the body reduce heat-generating muscular work and increase heat loss to cope with hyperthermia (overheating)?
heat induced cramps cause athletes to stop exercising
deprive muscle of energy
How does the body deprive a muscle of energy when it needs to cool down?
Pyruvate kinase deactivates at 40 degrees Celsius, shutting down ATP production and muscle function
