Famous quote (25)

“The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom.”
(Isaac Asimov)

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Sigg bottle - DNA replication

Video about London Dispersion Forces

Tattoo - Nature

Metabolic map about prions

Cartoon about what to do in case of radioactive spill

Believe or not, these are real instructions... lol

Intermolecular forces and melting/boiling point

One thing that tends to make confusion to my students is the relationship between non-covalent intermolecular forces and the melting/boiling point of a substance. In fact, how one can explain in a molecular point of view, the existence of the liquid and solid states? The answer lies precisely by the existence of intermolecular forces. Both states are characterized by a higher order spatial distribution of the molecules compared to the gaseous state. This order is a consequence of the attractions between the different molecules that make up a substance. Thus, in the liquid state, each molecule establishes various interactions (non-covalent!) with neighboring molecules, and in the solid state the amount of interactions is further increased.

When it is reached the melting/boiling point, which is going on is a transition from a state in which there are more intermolecular forces to one where there are fewer. In other words, what is being done is to provide energy to break the non-covalent forces established between the molecules, by increasing their kinetic energy.

Therefore, the greater the intensity of the non-covalent forces existing between the molecules, the greater the amount of energy required to break these interactions, and thus the higher the melting/boiling point.

I often ask to my students what happens when it is reached the boiling point of a substance, and the answer that I invariably get is: "You are breaking the bonds." The problem comes when I ask what kind of bonds, because usually their tendency is to say the covalent bonds. I, playfully, then tell them that if so, the water in the gaseous state is no longer H₂O, and then they realize that indeed that what it is cleaved are not the covalent bonds but the non-covalent ones.

In short, there is a direct relationship between intermolecular forces and melting/boiling point, and the greater the sum of these forces, the higher the melting/boiling point of a substance.

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Music about metabolic energy

The Beatles, with its famous song Let it Be, inspired Dr. Ahern to make a music about metabolic energy... :)

Download the music here

En-er-gy

Instructor sings
When I was walking through the forest
Grizzly bears came after me
So I was badly needing
En-er-gy

My body dumped some epinephrine
Out into the blood for me
'Cause I was badly needing
En-er-gy

Everyone sings
En-er-gy / En-er-gy
En-er-gy / En-er-gy
I was badly needing
En-er-gy

Instructor sings
The epinephrine gave a kick to
Enzymes deep inside of me
To make a bunch of cyclic
AMP

And when this hit my protein kinase
Catalytic ecstasy
The C subunits started
Adding P's

Everyone sings
Adding P's, adding P's
Adding P's, adding P's
Phosphorylation city
Adding P's

Instructor sings
The protein kinase put a phosphate
Onto PBK for me
Using energy from
ATP

And PBK in turn provided
GPa from GPb
So I released a ton of
G1P

Everyone sings
G1P / energy
G1P / energy
California needs some
G1P

Instructor sings
And when the chaos had subsided
I consumed some Frito Lays
Which soon began reversing
These pathways

The glucose halted epinephrine
Insulin began the race to
Turn on Phosphoprotein
Phosphatase

Everyone sings
Phosphatase - cleaves the P's
Phosphatase - cleaves the P's
The dephosphorylation
Cleaves the P's