Viewing a single comment thread. View all comments

slashdave t1_jbvw6c1 wrote

>But the scale is far too small for those sorts of concepts of rigidity or even solidity, right?

No, atoms are solid, and the bonds in the molecules are usually quite strong. The lock-and-key analogy is not very good, however. For one thing, molecules and proteins are not rigid. And the binding is a statistical process. It's just that the protein and molecule prefer (by favorable energy and entropy) to be together then apart in solution.

2

Eat-A-Torus OP t1_jc232er wrote

how are they solid? I thought most of a molecule is empty space, with little bits of solids protons/neutrons in the nucleuses, and the electrons diffused in a cloud around them?

1

slashdave t1_jc2e8px wrote

Atoms repel each other quite strongly using what is described as "Van der Waals" forces (electrostatic in nature). The length of bonds between atoms are relatively inflexible and keep bonded atoms close enough to prevent other atoms from slipping between.

For example, proteins often fold around and trap water molecules within their structure. Many of these water molecules remain trapped until the protein decays.

1