Understanding Warm-Blooded Animals and Their Cells

Warm-blooded animals, or homeotherms, such as mammals and birds, maintain a constant internal body temperature generally ranging from about 35°C to 40°C. Their cells are adapted to function optimally at these temperatures. However, for storage and preservation, cells cannot be kept at body temperature, as metabolic activities would continue, leading to nutrient depletion and cell death.

Why Temperature Matters in Cell Storage

Temperature directly influences cellular metabolism, enzyme activity, and the stability of cellular structures. Lowering the temperature slows down metabolic processes, reducing energy consumption and prolonging cell survival. However, if the temperature is too low or too high, it can cause irreversible damage.

Common Temperature Ranges for Cell Storage

• 37°C (Option 1): This is the normal physiological temperature for warm-blooded animals. While ideal for cell growth and culture, it is unsuitable for long-term storage because cells remain metabolically active and will eventually die without nutrients.

• 0°C (Option 2): Near freezing, this temperature slows metabolism but can cause ice crystal formation inside cells, damaging membranes and organelles unless special cryoprotectants are used.

• -100°C (Option 3): Ultra-low temperatures like this are used in specialized freezers. Metabolic processes nearly stop, but ice crystal formation can still be an issue without cryoprotectants.

• -196°C (Option 4): This is the temperature of liquid nitrogen, the gold standard for cryopreservation. At this temperature, all metabolic activities cease, and cells can be preserved for years or decades without damage, provided cryoprotectants are used.

Best Temperature for Long-Term Storage

For long-term preservation of cells from warm-blooded animals, -196°C (liquid nitrogen temperature) is the best choice. At this temperature:

• Cellular metabolism is completely halted.

• Ice crystal formation is prevented when combined with cryoprotectants like DMSO.

• Cells remain viable for extended periods without degradation.

This method is widely used in biobanks, fertility clinics, and research laboratories worldwide.

Supporting Research Insights

Studies have shown that storing cells at temperatures above freezing but below physiological levels (e.g., 0°C to 5°C) can only preserve cells for short durations (hours to days). For longer storage, cryopreservation at liquid nitrogen temperatures is essential to maintain cell integrity and function.

Conclusion

The cells of warm-blooded animals are best stored for long durations at -196°C, the temperature of liquid nitrogen, to ensure maximum viability and preservation. This ultra-low temperature halts all metabolic activity and, when combined with proper cryoprotectants, prevents cellular damage.

Correct answer:
(4) -196°C