Whisperer

On its own, one *hydrogen bond* is very weak. It has only a fraction of the strength of a normal bond. It is easy to break.

"But together?" Beaker grinned. "Together, they are incredibly strong."

He picked up a cup of water.

"Without these weak bonds, water would boil instantly," Beaker said. "It would turn to gas at room temperature. There would be no oceans. There would be no life on Earth."

The tiny bonds hold the liquid water together. They give water its high boiling point. They let ice float on top of ponds. They even create surface tension. That is the invisible skin that lets bugs walk on water.

Beaker pulled out a small glass of water and a metal paperclip.

"Watch this," Beaker whispered.

He carefully laid the paperclip on top of the water. It did not sink. It floated right on the surface.

"How is that possible?" asked Leo, leaning forward. "Metal is heavy!"

"Whisperer is holding it up," Beaker said. "The water molecules are holding hands. They form a tight net on top. That is surface tension."

He tapped the water with his finger. The paperclip sank to the bottom with a tiny clink.

"Once you break the bonds, the net tears," Beaker explained. "They break easily. But they also find new partners in a split second."

"So they are like dancers?" Leo asked.

"Exactly," Beaker said. "They dance and swap partners constantly. That is why water flows so well."

Beaker pulled out a giant model of DNA. It looked like a twisted ladder.

"Look at the rungs of the ladder," Beaker said.

He pointed to the chemical bases.

"This is DNA," Beaker said. "The double helix — the twisted ladder shape that holds all your genetic instructions."

The two sides of the ladder are held together by *hydrogen bonds*.

"Adenine and Thymine pair up with two bonds," Beaker explained. "Guanine and Cytosine pair up with three."

These bonds are strong enough to hold the ladder together. But they are also weak enough to unzip.

"Imagine a zipper on your favorite jacket," Beaker said. "If the zipper was glued shut, you could never open it. If it was too loose, your jacket would fall off."

The kids laughed.

"DNA is the same way," Beaker said. "It needs to stay closed to protect your genes. But it must open when your cells want to read the recipes inside. Whisperer makes sure the zipper works perfectly."

Beaker reached for a messy, folded plastic ribbon.

"Proteins do all the hard work in your body," he said. "But they have to fold into perfect shapes first."

He showed how the ribbon curled into spirals and folded into sheets.

"These are alpha-helices and beta-sheets," Beaker said. "They are just fancy names for spirals and folds."

"What keeps them in shape? Whisperer does."

Without these tiny dashed lines, the proteins would unroll. They would stop working completely.

Beaker lined up four different models on his desk.

"Let us look at our four bond friends," Beaker said.

He pointed to the first model.

"Tugger transfers electrons fully to make ionic bonds," he said.

He pointed to the second model.