"Look at this animation."
Milia showed her tablet. On the screen, a long chain folded into a complex structure.
"A protein?" Kana peered in.
"Yes. A miracle happening thousands of times right now inside cells."
Rei watched with interest. "Folding is spontaneous. All the information is contained in the amino acid sequence."
"What do you mean?" Kana asked.
Milia began explaining. "Proteins are made of small building blocks called amino acids connected together. Twenty types of amino acids arranged in a specific order."
"Only twenty types?"
"But the combinations are infinite. With 100 amino acids, it's 20 to the 100th power."
Rei supplemented. "That sequence determines the final three-dimensional structure. Like a recipe."
Kana looked at the animation again. "But how does it know the 'correct' shape?"
"Thermodynamics," Rei answered. "Proteins search for the state with lowest energy. Hydrogen bonds, hydrophobic interactions, electrostatic forces... various forces at work."
Milia pointed at the screen. "Look at this part. Hydrophobic amino acids are trying to hide inside."
"Hydrophobic?"
"Water-fearing property. Oily amino acids cluster inside in water. Hydrophilic amino acids go outside."
Rei continued. "This is the main driving force of folding. A complex process intertwined with entropy."
Kana pondered. "But with all this complexity, doesn't it make mistakes?"
"It does sometimes," Milia's face became serious. "Misfolding causes diseases."
"Diseases?"
Rei gave an example. "Alzheimer's disease. Proteins fold into abnormal shapes and accumulate in the brain."
"That's scary..."
"Prion diseases too," Milia added. "Normal proteins change infectiously into abnormal shapes."
Kana stared at the animation. Midway through folding, the chain seemed to hesitate and waver.
"What's happening at this moment?"
Rei explained. "It's exploring the energy landscape. Testing multiple possibilities while finding the optimal shape."
"But why is it so fast? In this video it's just seconds."
"Actually, microseconds to milliseconds. There was a mystery called Levinthal's paradox."
Milia continued. "If it tried randomly, calculations show it would take longer than the age of the universe. But it happens instantly."
"Then how?"
"There's a pathway," Rei drew a diagram. "Not completely random, but folding stepwise through intermediate states."
Kana's eyes lit up. "Like a map?"
"Yes. Called a folding funnel. Many starting points converging to one endpoint."
Milia operated the tablet. "There are also helper proteins called chaperones. They prevent misfolding."
"Helpers?"
"Cute way to put it, but they play an important role. Without chaperones, proteins would aggregate."
Rei added. "Inside cells is crowded. Chaperones protect proteins from incorrectly binding to other proteins."
Kana replayed the animation from the beginning. A single chain transforming into a beautifully ordered structure.
"It's like poetry."
Milia smiled. "Poetry of life. The moment information becomes form."
"Information from DNA converts to amino acid sequence, which further converts to three-dimensional structure," Rei organized.
"Three-stage information transformation."
Kana murmured. "This miracle happens millions of times per second in my body."
"Several million times, yes," Milia answered.
The three stared at the screen. Proteins folding. In that moment, life dwells.
"Beautiful," Kana said.
Rei and Milia nodded too. At the boundary of science and art, they shared silence.