Denaturing leaves the backbone whole
- The idea
- Predict
- See it
- Why
- Check
The idea
“When heat or acid denatures a protein or DNA, it breaks the molecule into its building blocks.”
Denatured sounds like destroyed, and a cooked egg looks nothing like a raw one. What broke were mostly the weak bonds holding the shape.
The short version
The mistake: When heat or acid denatures a protein or DNA, it breaks the molecule into its building blocks.
What's actually true: Heat, pH changes and denaturants break the weak bonds that hold a molecule's shape. The covalent backbone stays whole.
- Strong covalent bonds join a polymer's units. Peptide bonds link amino acids, and phosphodiester bonds link nucleotides.
- Shape is held mostly by weak interactions, such as hydrogen bonds, ionic attractions and hydrophobic contacts. Heat, pH changes and denaturants disrupt them.
- A denatured protein loses its secondary, tertiary and any quaternary structure. It keeps its primary structure, the amino acid sequence.
- Cutting the backbone takes hydrolysis. In cells, proteases cut peptide bonds and nucleases cut phosphodiester bonds.
On the exam: Denaturing breaks the weak bonds that hold the shape. The covalent chain and its sequence stay whole.