Final answer:
The separation of strands in a double-stranded DNA molecule due to high temperature is called denaturation. The process is reversible and is used in biotechnological applications like PCR.
Step-by-step explanation:
When a double-stranded DNA molecule is exposed to high temperature, resulting in the separation of the two strands, this process is referred to as denaturation. Denaturation occurs when the hydrogen bonds between bases are disrupted due to extreme pH conditions or higher temperatures, typically above 80 to 90 degrees Celsius. The melting temperature, or TM, indicates the temperature at which a DNA molecule is 50% denatured.
The process of denaturation is reversible; upon cooling or removal of chemical denaturants, the strands can rewind or anneal due to the reformation of hydrogen bonds between the complementary bases. This characteristic is leveraged in biotechnological applications such as the Polymerase Chain Reaction (PCR), where DNA replication is initiated after the denaturation and annealing steps.